The Science Behind the Art™

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Author: Russell Stafford

Hortiholic and plant evangelist, Russell Stafford, transplanted his first perennial at age 7 and thereby began a lifelong plant addiction. He is the founder and custodian of Odyssey Bulbs (and Odyssey Perennials), an online nursery specializing in cool and uncommon plants. Russell also works as a horticultural consultant, freelance writer (Horticulture and The American Gardener magazines), and garden editor. He formerly served as Curator and Head of Horticulture at Fernwood Botanic Garden in Niles, Michigan and as the Horticultural Program Coordinator at the Center for Plant Conservation, then located at the Arnold Arboretum in Jamaica Plain, Massachusetts. His academic degrees include a masters in forest science from Harvard University.

Holiday Euphorbias

The often spiny, often tropical genus Euphorbia has given us two of our most familiar holiday houseplants.

Although it’s spineless, the ubiquitous holiday centerpiece commonly known as poinsettia is, in fact, a Euphorbia, botanically speaking. The name Poinsettia was retired many years ago, when taxonomists moved the entire genus to its present nomenclatural location. (As an interesting side note, several species in the former genus Poinsettia are native to rather chilly regions of North America, including parts of the United States.)

But the common name poinsettia lives on.  It commemorates one Joel Poinsett, a Carolinian aristocrat of the early eighteenth century. Myth has it that Poinsett introduced the species to the U.S. from its native Mexico while he was envoy there.

Under whatever name, Euphorbia pulcherrima received little horticulture notice for the first 100 years after its introduction to cultivation in the late 1820s. It was too scraggly and lanky (not to mention cold-tender) for most gardens, and as a cut flower it was too short-lived.

Its potential as a holiday plant was considerable, however. Euphorbia pulcherrima naturally blooms around the turn of the year, and the blossoms (which are actually leaf-like bracts surrounding a small cluster of yellow flowers) can be quite showy. All the species needed was a bit of tweaking to accentuate its showiness and reduce its ranginess.

Enter Paul Ecke, his son, Paul Ecke, Jr., and the rest of the Ecke tribe. At their ranch in Encinitas, California, they developed an exclusive technique for propagating compact Euphorbia pulcherrima plants that bear full heads of bloom and fit easily on a table. The family also had a knack for marketing. By the 1960s, they had successfully established poinsettias as THE Christmas flower, and had captured the bulk of the poinsettia trade, grown at their Encinitas ranch. Many varieties of poinsettia are still developed at Ecke Ranch, although the plants are grown for market elsewhere.

Poinsettia varieties now number in the hundreds, in hues of pink to red to white to yellow, sometimes in combination. Dwarf varieties are also available.

 

It’s easy to keep poinsettias going after they’ve reached your holiday table. Bright indirect light, warmth (55F minimum), and moderate humidity are all to their liking. Water only when the soil surface is dry and the pot is appreciably lighter due to drying.

Instead of discarding your poinsettias after the holidays, you can keep them growing until next winter, and beyond. Repot rootbound plants in spring, using a somewhat coarse potting soil such as Fafard® Professional Potting Mix. If desired, shear them to a few inches in spring and pinch their shoots in summer to promote relatively compact bushy growth. Plants can be moved to a brightly shaded position outside after the last-frost date.

Poinsettias require long nights to flower. Bring them inside and give them at least 14 hours of darkness per day starting in early fall. With luck, you’ll have a free display of blooms for holiday season 2022/23!

 

 

 

A second – and characteristically prickly – holiday icon from the genus Euphorbia is crown of thorns, Euphorbia milii. Inflorescences comprising paired red-orange lip-shaped bracts cluster toward the tips of this spiny, sparsely branching, 2- to 3-foot shrub. Plants that receive ample light flower almost continuously. Spoon-shaped leaves are spaced along the branches, with plants becoming bare toward their base with age.

Numerous selections and hybrids of Euphorbia milii with larger flower bracts in a wide range of colors are available from specialty growers. Arguably the splashiest of these are the so-called “Thai Giant” cultivars that originated in Southeast Asia horticultural circles late last century (including the self-descriptive ‘Pink Charm’ and ‘Red Hot’). These plants have quarter-sized flower bracts that resemble a large-flowered begonia rather than a typical crown of thorns. Among the other variations on the crown of thorns theme are dwarf and variegated cultivars. All prefer lots of light and infrequent watering (water only when the soil mix is dry).

Garden Perennials that Gently Self Sow

Butterfly weed is a lovely native that will sow itself very gently and weave into the garden.

Some perennials persist in the garden not only as over-wintering plants, but also via self-sown seedlings. With their penchant for popping up spontaneously here and there, they’re a great fit for cottage gardens, wildflower borders, and other informal plantings. Additionally, they obviate the need for deadheading!

Unwelcome Self Sowers

Admittedly, a few perennials can take self-sowing too far. For example, a lemon balm (Melissa officinalis) that is allowed to go to seed will soon produce a population bomb, spawning gazillions of offspring. Although the plants profiled below typically self-sow in moderation, they can be more prolific in favorable situations. Keep an eye out and a hoe at hand just in case!

You’ll also want to discourage self-sowing by named varieties of perennial species whose seedlings are not true to type. Allow your pristine Phlox paniculata ‘David’ to self-sow, and you’ll likely soon have a flock of muddy-purple wild-type offspring. The same goes for many other groups of perennials, including columbines (Aquilegia spp.), and just about anything from the aster/daisy family, though on occasion their offspring can be quite pretty.

Aquilegia hybrids gently self-sow, but their seedlings yield various unexpected surprises.

Finally, avoid heavy applications of mulch in areas where you want to encourage self-sowing. Most perennial seeds will not germinate while are buried under a 3-inch stratum of shredded bark. A much more satisfactory method of controlling weeds is to allow desirable plants to seed themselves densely into any garden gaps and to keep the gaps weeded while the new seedlings develop. A light early-spring scattering of Fafard Premium Natural & Organic Compost is all the mulch you’ll need in an established, densely populated border.

Welcome Self Sowers

Black cohosh, bugbane (Actaea racemosa)

The white flower spikes and ferny foliage of black cohosh are both attractive.

Native to moist fertile woodlands over much of the eastern U.S. from zones 4-8, this imposing perennial produces moderate numbers of seedlings in similar garden habitats. Mature plants form ferny-leaved, 3-to 4-foot clumps, surmounted in summer by white bottlebrush flower spikes. Several other U.S. native bugbanes are also well worth growing, most notably the relatively compact, bold-leaved, late-summer-blooming Actaea rubifolia.

Blue-star (Amsonia spp.)

The pale flowers of Arkansas blue-star mingle with tall Allium.

Most members of this mostly North American genus will self-sow obligingly (but not invasively) in sunny to lightly shaded garden niches. Almost all amsonias are large, upright, long-lived clump-formers with handsome, lance-shaped, disease-resistant foliage and starry, light blue, late-spring flowers. Arkansas blue-star (Amsonia hubrichtii, Zones 5-9) is especially handsome, thanks to its extremely narrow leaves that lend its 3-foot clumps a hazy, dreamy look. It’s also one of the most reliable self-sowers of the lot.

Butterfly weed (Asclepias tuberosa)

Both butterflies and bees are attracted to the bright flowers of butterfly weed.

A durable eastern U.S. native for hot dry sunny niches, butterfly weed summons early-summer pollinators with its brilliant flat-headed clusters of orange to yellow flowers on 2-foot stems. The ensuing seed pods split open to release downy seeds that float away on the summer breeze – and germinate the following spring. Volunteer seedlings can be sparse to abundant, depending on wind patterns and other vagaries. Grow it in zones 3-9.

Bleeding heart (Dicentra spp.)

Fringed bleeding heart is an exceptional native for pollinators.

Fringed bleeding heart (Dicentra eximia, Zones 3-9) would be worth growing for its lacy, finely divided, blue-green foliage alone. For most gardeners (and hummingbirds), though, it’s the flowers (which resemble fanciful pink flasks rather than hearts) that are the primary feature of this lovely eastern U.S. woodlander. Bloom repeats sporadically from spring through fall, spawning the occasional seedling. Hybrids (such as ‘Luxuriant’) between Dicentra eximia and its western U.S. cousin Dicentra formosa (Zones 4-8) are sterile and seedless. At around a foot tall, Dicentra eximia and its hybrids are miniatures compared to the species whose cordate flowers inspired the common name “bleeding heart”. The purple-pink hearts of Dicentra spectabilis (recently re-dubbed Lamprocapnos spectabilis, Zones 3-9) open in mid-spring on arching stems that ascend to 3 feet or more. There’s also a beguiling white-flowered variant. All manifestations of the species self-sow modestly and true to form.

Gas plant (Dictamnus albus)

Gas plant blooms have a sweet citrusy scent.

Slow from seed and in growth, gas plant is one of a multitude of splendid perennials that are rarely offered because they are a poor fit for mass-market plant production. Give it a few years, and it will mature into a 3-foot hummock of lustrous, dark-green foliage decked in late spring with spikes of fragrant, showy purple or white, hummingbird-seducing flowers. One of the best strategies for propagating this long-lived Eurasian native is to wait for volunteer seedlings, which occur sporadically. Gas plant has only one liability as an ornamental: in rare instances, the volatile oils that inspired its name can cause blistering and other symptoms of acute dermatitis. These volatile compounds are also responsible for a time-honored garden ritual. Hold a match near the plant on a calm warm evening and its “gases” will briefly flare into flame. Grow in zones 3-9.

Purple coneflower (Echinacea purpurea)

Here purple and white coneflower variants mingle in a naturalistic garden.

No need to plant more of this beloved Midwest native: once it’s in your garden, it will almost certainly give you a scattering of volunteers. Expect to see their rose-pink, dark-coned flowers within a year after they germinate. Seedlings of the slew of recently introduced hybrids involving Echinacea purpurea (Zones 4-9) and the yellow-flowered Echinacea paradoxa (Zones 4-9) are a different story. Even if they survive the winter – a dubious proposition in USDA hardiness zones 6 and lower – they’ll produce flowers unlike those of their parent.

Rattlesnake master (Eryngium yuccifolium)

The unique foliage and flowers of this prairie native add interest to native gardens. (Image by Kurt Stueber)

You might think that a perennial with yucca-like foliage (and a botanical name to match) would favor arid conditions. In fact, Eryngium yuccifolium (Zones 3-9) often occurs in moist habitats in its native range, which spans much of eastern and central North America. Give it a reasonably fertile, not too dry garden soil, and it will send up 4-foot stalks in midsummer, topped by spheres of silvery flowers. Allow it to seed, and you’ll be rewarded with progeny the following spring.

Bearfoot hellebore (Helleborus foetidus)

The pale chartreuse flowers of bearfoot hellebore bloom in late winter to early spring.

Most hellebores self-sow, given the opportunity. Helleborus foetidus (Zones 5-8) is perhaps the most adaptable and fecund of the lot, prospering and self-propagating in sun and shade. A member of the shrubby side of the tribe, it bears leaves and pale chartreuse flowers on upright stems that can ascend to 18 inches or more. The foliage is pleasantly pungent rather than unpleasantly fetid.

Cardinal flower (Lobelia cardinalis)

Cardinal flower spikes have blooms of the purest red imaginable.

The brilliant red spires of cardinal flower (Zones 3-9) are a common midsummer sight in wetland habitats of eastern and central North America. Quite often they’re attended by adoring hummingbirds. Relatively short-lived in the garden, they persist by sowing themselves into moist exposed soil, germinating into evergreen rosettes. Equally wonderful is blue cardinal flower (Lobelia siphilitica, Zones 4-8), another eastern North American native and midsummer hummingbird fave. It succeeds in just about any garden position except deep shade. Its white-flowered form is also compelling.

Virginia bluebells (Mertensia virginica)

Virginia bluebells will make any spring garden look lovely.

Give this eastern U.S. native (Zones 3-9) a good moist soil in partial shade, and it will spread freely both from underground rhizomes and from self-seeding. A member of the borage family, it produces the blue flowers typical of the tribe. The blue-green, tongue-shaped leaves go dormant soon after the flowers fade in late spring.

Celandine poppy (Stylophorum diphyllum)

Wooded native gardens are suited to celandine poppies.

An excellent shade-garden companion for Virginia bluebells (as well as trilliums and woodland phlox), this reliably self-sowing eastern U.S. native (Zones 4-9) bears glistening yellow mini-poppies on 18-inch plants clothed in large lobed leaves. Its East-Asian analog Stylophorum lasiocarpum blooms in summer.

Among the numerous other perennials that seed themselves are:

  • Blazing star (Liatris spp.);
  • Patrinia (Patrinia spp.);
  • Beardtongue (Penstemon spp.);
  • Balloon flower (Platycodon grandiflorus);
  • and Yellow fumitory (Pseudofumaria lutea).

They’re living proof that going to seed is not necessarily a bad thing!

Spring Snowdrops and Snowflakes

Spring snowflakes are among the prettiest, most delicate flowers of early spring.

Ah, the first snowdrop of spring. Or is it a spring snowflake? Both are early-blooming bulbs that bear nodding, white, 6-parted flowers above clumps of strap-shaped leaves in late winter, while most of the garden is still slumbering. Both also favor similar garden habitats – namely, partial shade to sun and well-drained, humus-rich soil. It’s no surprise, then, that they’re often mistaken for one another – and that they’re also closely related.

Snowdrops versus Spring Snowflakes

It’s a bit more complicated than that, though – especially on the snowdrop side of the equation. Spring snowflake (Leucojum vernum) is a single species, native to meadows and woodland edges of central and eastern Europe. Snowdrops, in contrast, comprise more than 20 species scattered over much of Europe and western Asia. Most snowdrops flower early in the year, but a few bloom in fall or early winter, bringing the flowering season to a close rather than ushering it in. Many Galanthus also interbreed readily, as evidenced by the hundreds of named garden hybrids. Snowdrops aren’t an “it” – they’re a multifarious “them”. Bees or all kinds pollinate the blooms.

For all their similarities, snowdrops and spring snowflake do differ in several respects, most obviously in the form of their flowers. Spring snowflake flowers are typically lantern-shaped, with each segment being of roughly equal length and having a pointed, out-curved, green-blotched tip. In snowdrops, the inner three inner petals are small, linear, and notched at the tip, together forming a tubular structure at the flower’s center. The three outer segments are spoon-shaped and approximately twice the length of the inners. They clasp tight in bud, giving unopened flowers a teardrop shape (hence the common name). Usually, each inner segment sports a green terminal blotch, around the segment’s notched tip (or “sinus”).

Snowdrop Species and Varieties

Common snowdrops naturalize beautifully in the landscape.

A few snowdrop varieties depart significantly from the norm, with such oddballs sometimes fetching exorbitant prices. Cultivars sporting doubled inner segments, green-marked outer segments, or same-sized inner and outer segments are available from bulb merchants and snowdrop specialists. Also on offer are a few highly prized variants with yellow – rather than green – markings, a rare mutation that occurs in summer snowflakes as well.

Snowdrops were formerly collected from the wild for the horticultural trade, a practice that posed a survival threat to several Galanthus species. The genus is now protected under international law, reducing pressure on wild populations. Still, be wary of sources that offer quantities of snowdrops at bargain-basement prices.

The yellow-marked ‘Sandersii’ common snowdrop is rare and choice.

As befits its vernacular name, the common snowdrop (Galanthus nivalis) has been a popular garden plant since Renaissance times and is still by far the best-known member of the tribe. A rather diminutive thing, it produces half-inch-long “drops” on 4- to 6-inch stems framed by narrow, almost grassy leaves. Varieties include ‘Flore Pleno’, whose fully double inner segments form a white, green-fringed pompon at the flower’s center; ‘Viridapice’, with green-stained outer segments; and yellow-marked selections ‘Sandersii’ and ‘Blonde Inge’. Given its relatively small size, Galanthus nivalis is best planted in groups, to maximize its impact. It’s hardy to USDA Zone 4.

Crimean snowdrop (Galanthus plicatus) is a more substantial species, with its handsome, broad, dark green leaves and large flowers. (Image by Сергій Криниця (Haidamac))

Crimean snowdrop (Galanthus plicatus) is a more substantial species, making a bold statement in the garden via its handsome, broad, dark green leaves and its inch-long, rounded flowers on 6- to 8-inch scapes. It’s thus well suited as a specimen plant – which is just as well, given its relative priciness. Pricier still are Crimean snowdrop cultivars such as ‘Diggory’, remarkable for its expanded, Japanese-lantern-shaped buds; and the self-explanatory ‘Colossus’. Galanthus plicatus also comes in yellow-blotched forms, most notably ‘Wendy’s Gold’. Most forms of the species are quite hardy, to Zone 5.

Galanthus woronowii has large, strappy leaves and elegant blooms. (Image by Peter Coxhead)

Galanthus woronowii is another snowdrop distinguished by broad, attractive leaves – glossy bright green in this case. The flowers – while not quite as large or rounded as those of Crimean snowdrop – are more than presentable, with dapper olive-green sinus marks and elegantly modeled outer segments. Native to mountainous regions of NE Turkey and SW Russia, it’s hardy into Zone 5.

Giant snowdrop is indeed one of the goliaths of the genus.

Yet another species worth growing for its foliage as well as its flowers is giant snowdrop, Galanthus elwesii. It is indeed one of the goliaths of the genus, with 1- to 1.5-inch-long flowers borne on 6- to 10-inch stems, above erect clumps of lance-shaped, gray-green leaves. The inner flower segments of some forms of this highly diverse species have green markings at the base as well as at their tips. Flowering time also varies widely, with a few forms flowering in fall, and still others delaying bloom until mid-spring. Native from SW Europe through much of Turkey, Galanthus elwesii is somewhat less hardy than the other snowdrops described here, wintering into milder regions of Zone 5. Many cultivars are available from snowdrop specialists, including the exceptionally large-flowered ‘Comet’.

Antique Snowdrops

The vigorous cultivar ‘Atkinsii’ is still treasured for its elegant pearl-drop-earring-like blooms.

Of the numerous outstanding hybrids between the above (and other) Galanthus hybrids, among the best (and most affordable) are some of the old-time favorites. Originating nearly 150 years ago, the vigorous cultivar ‘Atkinsii’ is still treasured for its elegantly modeled flowers that have been likened in shape to pearl-drop earrings. The inners bear heart-shaped sinus marks.

Also dating back to the nineteenth century is ‘S. Arnott’, valued then and today for its large white flowers with chevron-shaped, olive-green sinus marks. Or even earlier in origin is the Irish cultivar ‘Straffan’, which typically produces two flowers per stem, rather than the usual singleton. It’s also notable for its relatively late season of bloom. Another vigorous old-timer, ‘Magnet’ dangles its classic drop-shaped flowers on long gracefully arching pedicels.

‘Magnet’ dangles its classic drop-shaped flowers on long gracefully arching pedicels. (Image by Russell Stafford)

One of several outstanding double-flowered snowdrops developed in the mid-twentieth century by British galanthophile Heyrick Greatorex, ‘Ophelia’ displays a central rosebud of heavily green-stained inner segments, with two flowers often occurring per stem.

Although some specialists sell Galanthus “in the green” in spring, snowdrops are best planted as dormant bare-root bulbs in fall. To provide your snowdrops with the humus-rich, well-drained soil they prefer, be sure to dig in some Fafard Premium Natural & Organic Garden Compost before planting them. They’ll reward you by brightening your garden and your spirits next winter and spring.

Cool Season Annuals for Spring and Fall

Snapdragons are classic cool-season annuals that make glorious cut flowers.

Annuals aren’t just a summer thing.  True, many popular annuals – such as marigolds, zinnias, castor beans, portulacas, and celosias – are unabashed heat-lovers, languishing in chilly conditions and hitting full stride during the long sultry days of July and August. Among the most valuable annuals, however, are those that thrive in cool weather. They’re especially useful for filling the floral doldrums that tend to haunt gardens in late spring and fall.

Most cool-season annuals germinate reliably in relatively chilly soil (below 45 degrees F) and tolerate a goodly amount of frost. Sow them outdoors in late winter or early spring (depending on your locale), and they’ll be up and flowering well before the summer annuals get going. Or for extra-early bloom, start plants indoors and transplant them to the garden several weeks before the last frost date. Cool-season annuals take center stage again in the fall. Sow them 3 months before the first frost date for a late floral display, or plant out store-bought plants in late summer.

Great Cold-Hardy Annuals

Some especially cold-hardy annuals – including all of those described below – will even overwinter as seed or seedlings into USDA hardiness zone 6/7 (or colder, in some cases), arising in spring to bloom weeks before spring-sown plants. These can be planted in the garden in the fall as seeds or young transplants, or existing plantings can be allowed to self-sow. If you’re starting plants indoors, be sure to give them lots of light and a good potting mix such as Fafard Ultra Container Mix with Extended Feed.

Pansies and smaller-flowered Violas are cool-season musts for the garden.

Pansies (Viola × wittrockiana) are among the most popular cool-season annuals – and for good reason. Not only do they flower continuously in fall and early spring (and beyond), but they also throw some blooms during mild winter spells in USDA zones 6 and warmer. Sold by the thousands in garden centers and other venues in fall and spring, they come in all colors, usually with a signature deep-purple “face” at the flower’s center. Violas – hybrids of Viola cornuta – are close relatives of pansies that also flower prolifically during the cool seasons, as well as in winter warm spells. Short-lived perennials typically bear smaller flowers than those of the pansy tribe, with streaking rather than “faces” at their centers. Both pansies and violas do well with either early-spring or late-summer sowing and planting. The Victorian Posy Pansy mix is an excellent choice for those who start their own flowers from seeds.

Snapdragons can make a grand statement in the spring garden.

Like pansies, snapdragons (Antirrhinum majus) overwinter outdoors throughout much of the U.S., making them ideal candidates for late-season planting into USDA zone 5. Overwintered seedlings bloom early in the season, lifting their colorful spires to the sun in late spring. In USDA zones 5a and colder, start seed indoors in late winter, a few weeks before the last-frost date. Early-blooming snapdragon varieties such as those in the Potomac, Chantilly, and Costa series provide an additional head-start on the flowering season, blooming days to weeks earlier than other varieties. They flower in the full range of snapdragon colors, including white, yellow, pink, red, and purple.

Large-flowered gloriosa daisies are ideal cool-season annuals for the fall.

Also ideal for fall planting are gloriosa daisies (Rudbeckia hirta), which are exceptionally winter-hardy (to USDA zone 3). Overwintered plants open their bright yellow to burgundy “black-eyed Susan” flowers in late spring or early summer, repeating until frost. Varieties include ‘Indian Summer’, with classic bright yellow “black-eyed Susan” flowers on 3-foot stems; ‘Cherokee Sunset’, whose double blooms on 30-inch stems come in various tones and combinations of yellow, bronze, and maroon; and the green-coned, tawny-eyed ‘Prairie Sun’. If seedlings don’t survive winter in your area, try sowing seed in the garden in fall, for early germination next spring. Plants will readily self-sow if you don’t deadhead them. Of course, late winter or early spring sowing works too, either indoors or out.

Classic blue cornflowers can be sown in the fall for spring.

Other classic candidates for fall planting or sowing for spring are Larkspurs (Consolida ajacis) and cornflowers (Centaurea cyanus). They bring an abundance of blue to the late spring garden, in two different forms. Larkspurs produce quantities of dainty butterfly-shaped blooms on 30- to 50-inch spikes. Cornflowers, in contrast, bear frilly pompons atop wiry 3- to 4-foot stalks. In addition to classic blue varieties such as ‘Blue Spire’, larkspurs come in an assortment of other colors including white, pink, lavender, and combinations thereof. Cornflowers, too, are available in a wide color range, from blue (e.g., ‘Blue Diadem’) to pink to red to maroon.

Lesser-Known Cool-Season Annuals

The ranks of cool-season annuals that do well with spring or fall planting or sowing include a number of relatively little-known but highly ornamental species that deserve much wider use:

Blue woodruff is rarely grown and deserves more garden attention. Expect some self-sowing.

 Blue woodruff (Asperula orientalis) throws airy sprays of little sky-blue flowers on low, typically lax stems. It’s especially lovely in containers, making a lacy understudy for bigger, bolder leaved annuals such as flowering tobaccos and amaranths.

Also flowering in blue is Chinese forget-me-not (Cynoglossum amabile). The clusters of rounded, bright blue blooms do indeed recall those of standard forget-me-not (Myosotis spp.), but they occur on much more durable plants that blossom in late spring and repeat in summer and fall. The pink-flowered variety ‘Mystery Rose’ is equally ornamental.

Toadflax just grows in the cool season, but it is so delicate and pretty.

A perky little thing with spikes of bright blooms that resemble snapdragons, Moroccan toadflax (Linaria maroccana) is perfect for massing in garden beds and containers, in forms such as the pastel assortment ‘Fairy Bouquet’ or bright purple ‘Licilia Violet’.

The poppy tribe contains several cool-season treasures, none better than Shirley poppy (Papaver rhoeas), with its numerous pastel (such as ‘Mother of Pearl’ and the Falling in Love mix) and red (e.g., ‘American Legion’) forms; and Spanish poppy (Papaver rupifragum), a cheerful orange-flowered thing that’s especially winning in its double-flowered form, ‘Flore Pleno’ or ‘Tangerine Gem’.

‘Tangerine Gem’ is a very easy Spanish poppy to grow.

Although not quite as cold-hardy as most of the above, Green-gold (Bupleurum griffithii) weathers winters to USDA Zone 7, and is amenable to late winter and early spring planting in colder zones. Its large flat-headed clusters of chartreuse blooms on 3-foot stems make splendid accents for cut flower arrangements.

Gesneriads for Bountiful Indoor Blooms

Streptocarpus ‘Polka Dot Purple’ is one of many colorful cultivars available.

Showy, funnel-shaped flowers; attractive, rounded, or lance-shaped leaves; and an overall velvety to fuzzy texture characterize members of the family Gesneriaceae, home to many popular flowering house plants including gloxinias (Sinningia speciosa), African violets (Saintpaulia spp.), and others. Collectively known as gesneriads, they have a dubious reputation for being fussy in cultivation. In fact, many are quite easy to grow, provided conditions are not too dry, wet, or cold.

In almost all cases, gesneriads prefer a well-drained, organic-rich, moderately moist growing medium (allow the surface to dry between waterings). Peat-based potting mixes with lots of perlite or grit usually work well, such as Fafard Professional Potting Mix. Moderate fertility is also best (apply a balanced gesneriad or African violet fertilizer every couple of months or so). Most favor a bright but not overly sunny exposure, such as dappled shade or an east- or west-facing window.

Haberlea rhodopensis is a rare, hardy gesneriad that grows well in rock gardens. (Image by Jessie Keith)

For some gesneriads, such as members of the genera Ramonda and Haberlea, anything above minus 15 degrees F or so is not “too cold”. These hardy gesneriads make good subjects for rock gardens and other well-drained, partly shaded garden sites into USDA Hardiness Zone 5. Most members of the family, however, are native to much milder, sub-tropical to tropical regions.

African Violets (Saintpaulia)

African violets come in all shades and colors. (Image by Jessie Keith)

The approximately half-dozen species of Saintpaulia hail from mountainous areas of equatorial East Africa (i.e., Kenya and Tanzania). By far the most familiar member of the genus is Saintpaulia ionantha, parent of most of the hundreds of hybrids collectively known as African violets. These come in a wide range of floral colors and sizes, from miniatures (2 to 6 inches wide) to “standards” (10 to 24 inches wide) to “trailing” varieties that creep and cascade to even greater lengths. Flowering continues sporadically year-round. A number of cultivars sport variegated leaves or double or striped flowers – or all of the above.

Real enthusiasts might want to explore species other than Saintpaulia ionantha (e.g. S. brevipilosa and S. confusa), which are available from a handful of specialist growers. Also available are wild-type forms of Saintpaulia ionantha itself, which is an utterly charming, abundantly blooming thing with periwinkle-blue flowers (or white, in cultivar ‘Alba’).

All members of the genus – and just about all tropical gesneriads – are happiest with moderate temperatures (60 to 80 degrees F) and relatively high humidity. African violets in particular resent cold water, especially on their leaves, which causes spots. Saintpaulia aficionados typically use room-temperature water, applied from below by immersing the container’s base.

Gloxinias (Sinningia spp.)

Florist gloxinia hybrids have very large blooms, and many different varieties are available.

So-called gloxinias (which actually belong to the genus Sinningia) have similar preferences. Most gardeners know them by the familiar large-flowered hybrids of the tuberous-rooted Sinningia speciosa. These “florist gloxinias” produce flushes of velvety, funnel-shaped flowers in shades of red, purple, white, or combinations of the same. Plants may stop blooming and even die back temporarily if things get too cool or dry, but they can usually be easily coaxed back into growth.

Lesser known – but in some cases even more satisfactory as house plants – are the 60-plus other species of Sinningia and their hundreds of hybrids, which come in numerous forms, sizes, and colors. Outstanding hybrids include ‘Tante’, a cascading plant with lax stems loaded with pale mauve trumpets, and ‘Prudence Risley’, which bears a constant succession of deep rose-red trumpet-flowers on 10-inch stems. Miniature, “teacup” Sinningia hybrids such as the salmon-orange-flowered ‘High Voltage’ are a great fit for terrariums or other small niches.

Cape Primroses (Streptocarpus spp.)

Cape primroses have tubular blooms in many bright colors.

Arguably the most floriferous gesneriads are the many hybrids of Cape primrose (Streptocarpus spp.), whose narrow-throated blooms with violet-shaped lobes are borne continuously, conditions permitting. The flowers are held on wiry, 3- to 8-inch stems above rosettes of tongue-shaped leaves that superficially resemble primrose foliage. Flower color range spans most of the spectrum, in a wide variety of patterns from solid to striped to speckled to picotee-edged. Streptocarpus typically mature at around 10 to 12 inches wide, but miniatures such as ‘Little Red’ are half that size or less.

Other Popular Gesneriads

Lipstick plant has fleshy leaves and lovely red, tubular flowers.

Hot water plant (Achimenes spp.)

The colorful trumpet-shaped flowers of these winter-dormant perennials are borne on leafy creeping stems that sprout from scaly rhizomes in the spring. Achimenes function well as house plants or in seasonal garden plantings.

Lipstick plant (Aeschynanthus spp.)

Clusters of beak-shaped red or orange flowers protrude from contrasting clasping sepals, on cascading stems lined with paired fleshy leaves. Lipstick plants – as well as the next three plant groups – are ideal subjects for hanging baskets in bright partly shaded locations such as an east window.

Goldfish plant (Columnea spp.)

Columnea hirta is one of many attractive goldfish plants for home gardeners to try. (Image by Guerin Nicolas)

The common name refers not to the color of the flowers (typically red), but to their arching shape, with fin-like petals protruding from their undersides. Like lipstick plants, they’re mostly of trailing habit, doing and looking well in hanging baskets in bright partial shade.

Guppy plant (Nematanthus spp.)

Yellow flowers with prominent paunches peek from the axils of the narrow, glossy, leathery leaves, giving the appearance of little fish sheltering in the greenery.

Flame violet (Episcia spp.)

Rosettes of colorful fuzzy leaves – often netted with flamboyantly contrasting veins – are the main attraction of this diverse genus. That said, some Episcia hybrids are grown mostly for their red, orange, pink, or yellow flowers, which are showy in their own right.

Lesser-known Gesneriads

Kohleria is a spectacularly beautiful lesser-known gesneriad.

Lots of other wonderful (and easy) members of the Gesneriaceae are there for the exploring, including:

Codonanthe

Close relatives of Nematanthus, these easy-to-grow gesneriads from uplands of eastern Brazil feature a compact, pendant habit, fleshy leaves, and small white or yellow flowers that repeat through much of the year.

Kohleria

Felted bugles line the relatively tall stems of this diverse tropical New World genus, which encompasses more than 20 species and scores of hybrids. Most flower in red, pink, orange, or purple, with contrasting flecking on their lips.

Smithiantha

These Central American natives send up compact spires of red, orange, yellow, purple, pink, or white flowers from stout compact rhizomes in spring and beyond. Plants go dormant for the winter. Smithiantha and Achimenes have combined to produce numerous beautiful intergeneric hybrids (known as ×Achimenantha).

Upon seeing all of the diverse and gorgeous gesneriads there are to grow, most plant collectors get hooked fast. Try a few to brighten your indoors this winter.

How To Force Spring Bulbs In Water

Flower bulbs, water, and a vase (or two) are all you need to bring a splash of spring to your windowsill this winter. It’s as simple as plant-growing gets. The water provides moisture for the bulbs’ roots. The vase provides a container for the water and support for the bulbs’ stems and leaves. And the bulbs take it from there. Everything’s inside these miraculous little plants-in-a-package: the buds, the roots, and the stored food that fuels roots and top growth. Give them the proper stimulus, and they’re off and blooming – no soil required, in many cases.

The author grows paperwhites in water each year around the holidays. (Image by Russell Stafford)

Paperwhites

Simplest of all are paperwhite narcissus, which require nothing more in the way of stimulus than a hit of water. Place several of them at the bottom of a bubble vase (illustrated) or a tall cylindrical glass vase (6 inches wide by 10 inches deep is an ideal size). Add around an inch of water (don’t worry – they’ll be fine). Move the vase to a cool dimly lit location. Finally, bring the vase out into cool full light when the bulbs begin to push roots. Re-water when necessary. In 3 to 5 weeks, you’ll have paperwhite blooms, their stems neatly propped by the sides of the vase. To further counteract flopping, amend the water with a touch of alcohol, which promotes compact growth.

Paperwhites set lush roots in water and bloom beautifully without chilling.

Most other bulbs are generally not as fine with sitting in an inch of water. Fortunately, you can buy forcing jars made just to address this challenge. The bulb nestles in a bowl-shaped receptacle at the top of the jar, which is filled with water just to the bulb’s base. Add water as needed to keep the developing roots immersed.

Amaryllis

Amaryllis are very easy to force in water/

Bulb-jars purpose-made for amaryllis (botanically known as Hippeastrum) are available from several suppliers. Some are vase-like bulb supports, while others provide space for pebbles to be placed at the base for root support. As with paperwhites, newly bought amaryllis can be forced directly with no pretreatment necessary. Within weeks, you’ll reap the reward of a spectacular display of huge, richly hued, trumpet-shaped blooms. (Click here to learn more about growing Amaryllis.)

Hyacinths, Crocus, and More

Crocus require a chilling period before they can be forced.

You’ll also find bulb-jars designed specifically for hardy bulbs such as hyacinths, crocuses, or whatever else will fit (scillas, grape hyacinths, trumpet daffodils, and early tulips are among the other bulbs that force well). Hardy bulbs present a special pretreatment challenge, though: many of them won’t send up flowers until they’ve experienced a few weeks of cold and have started rooting. One easy solution is to put the jarred bulb in a refrigerator or other chilly, dark place for several weeks, and move it into the light and warmth once roots extend and plump buds appear. Some hardy bulbs, such as Tazetta narcissus (including ‘Geranium’ and ‘Cragford’) and double hyacinths, need only cold; no rooting required. A few weeks in the refrigerator in a paper bag and they’re ready to head for their jars and get growing.

Forced crocus provide winter with a bit of cheerful spring color.

Or you can make your own “bulb jar”. Place pebbles in a narrow cylindrical vase, leaving a few inches of space at the top. Place the bulb (or bulbs) on the pebbles, and add water to the bulb’s base. Proceed as above. In a couple months, you’ll have spring in winter

Well-Mannered Groundcovers for Shade

Foamflower is a highly desirable native flowering groundcover for shade.

Back when one-size-fits-all gardening was a thing, ground covers for shade were seemingly as easy as one-two-three: creeping myrtle (Vinca minor), English ivy (Hedera helix), and Japanese spurge (Pachysandra terminalis). That is before they all began invading wildlands. All were neatly arrayed under an equally ubiquitous Norway maple or Bradford pear– both equally invasive and troublesome.

It was bound to happen. Introduce lots of one vigorous, spreading plant species, and you increase the likelihood that it will become a pest itself by invading local native plant communities. It did not take long for all three non-native, go-to ground covers to be added to the invasives lists of many U.S. states, particularly in the Southeast and Northwest.

Unfortunately, going ubiquitous presented additional problems in the garden. As anyone who has ever tried to maintain the “perfect” lawn and garden can attest, mass plantings are easy pickings for mass invasions of pests and diseases. Japanese spurge loses a lot of its allure when it’s riddled with Volutella blight, as is all too common these days.

Well-Mannered Groundcovers for Shade

Fortunately, excellent (and arguably superior) ground cover alternatives abound, many of them native. Feeding the soil with quality compost, such as Fafard Premium Garden Compost Blend, at planting time will encourage good establishment from the start.

Twilight Aster

Twilight aster blooms for a long period in summer and fall.

Who says ground covers have to hug the ground? Some situations call for something taller. Twilight Aster (Aster x herveyi ‘Twilight’ (aka Eurybia x herveyi)) spreads by rhizomes into large swards of broad-leaved rosettes that give rise in summer to leafy 2-foot-tall stems. Plants are crowned with clusters of pale lavender flowers for many weeks in late summer and fall. An incredibly adaptable thing, ‘Twilight’ can handle situations from dry shade to damp sun. This eastern U.S. native goes dormant in winter.

Sedges

Many native sedges are evergreen and make lush groundcovers for shade.

Botanically speaking, they’re not grasses, but sedges provide much the same look for shade with their clumps of narrow-bladed leaves. Masses of low sedges such as Carex pensylvanica and Carex rosea (both eastern U.S. natives) make excellent low-foot-traffic lawn substitutes. For a bolder look, try a clump of seersucker sedge (Carex plantaginea), whose strappy puckered evergreen leaves contrast effectively with lacier shade subjects such as ferns.

Green-and-Gold

Green-and-gold is semi-evergreen and bears loads of bright golden blooms in spring that attract native bees.

Green-and-gold (Chrysogonum virginianum) is a hardy, attractive woodland native. “Green” references the dense spreading rosettes of fuzzy, crinkled, heart-shaped leaves that hold their color and substance through much of winter. The “gold” is provided by the numerous little yellow “daisies” that spangle the plants in spring and repeat sporadically until fall. Native to woodlands in the Southeast U.S., Chrysogonum virginianum is hardy well north of that, to Zone 5.

Robin’s Plantain

This is one of those rare plants you can plug into the garden just about anywhere – sun or shade.

Often occurring as a rather doughty lawn weed, this plantain (Erigeron pulchellus) is a nearly evergreen eastern U.S. native that occasionally assumes much more pulchritudinous forms. The cultivar ‘Lynnhaven Carpet’, for example, grows into handsome carpets of broad fuzzy gray-green leaves that are decorated in spring with pink daisies on 18-inch stems. It’s one of those rare plants you can plug into the garden just about anywhere – sun or shade. Another delightful selection of robin’s plantain is ‘Meadow Muffin’, with contorted leaves that give its rosettes a bit of a cow-pie look.

Allegheny Spurge

Allegheny spurge has leaves that are elegantly splashed with silver mottling, lending the plant a distinguished look totally lacking in Pachysandra terminalis. (Photo by Zen Sutherland)

Although not a rapid runner like the aforementioned Japanese spurge, our Southeast native Allegheny spurge (Pachysandra procumbens) far outdistances it as a desirable ornamental. The whorled evergreen leaves – arrayed in mounded 6-inch-tall clumps – are elegantly splashed with silver mottling, lending the plant a distinguished look totally lacking in Pachysandra terminalis. Things get even splashier in spring when conical clusters of frilly white flowers push from the ground, along with the fresh-green new leaves, as the previous year’s foliage fades. It’s one of those early-season garden scenes that makes your heart leap up. Allegheny spurge thrives in moist humus-rich soil, so give it a dose of Fafard compost if your soil is overly sandy or heavy.

Ragwort

Golden flowers light up this native naturalizer in late spring.

Golden ragwort (Packera aurea) and its near look-alike roundleaf ragwort (Packera obovata) provide quick cover for more informal garden areas. Low swaths of bright green rounded leaves emerge from their rapidly spreading roots in early spring, followed a few weeks later by heads of small yellow “daisies” on 2-foot stems. Use golden ragwort in moist garden situations, and roundleaf ragwort in moist to dry niches. They’re both native to much of central and eastern North America.

Creeping Phlox

This evergreen woodland creeping phlox (Phlox stolonifera) from eastern North America will expand into a ground-hugging carpet.

Don’t let its rather dainty appearance deceive you: this evergreen woodland creeping phlox (Phlox stolonifera) from eastern North America will expand into a ground-hugging carpet of small spoon-shaped leaves. It also provides a spring garden highlight when it opens its clusters of proportionately large round-lobed flowers, poised on 6-inch stems. Blue-, pink-, violet-, and white-flowered selections are available, but probably the best for ground cover is the vigorous cultivar ‘Sherwood Purple’.

Whorled Stonecrop

A native sedum that thrives in shade? Yes!

If you think stonecrops are drought-loving sun plants, you’re probably not acquainted with Sedum ternatum. Hailing from moist partly shaded habitats over much of central and eastern North America, it makes an excellent small-scale ground cover in similar garden conditions, although it also succeeds in sunnier, drier sites. Its dense low hummocks of fleshy ear-shaped leaves are studded with sprays of white flowers in spring. This highly effective shade plant is still rather rare in gardens – perhaps because of its family associations.

Foamflower

Frothy 6-inch spikes of white flowers appear in spring above spreading expanses of handsome maple-shaped basal leaves. These features of foamflower (Tiarella cordifolia), combined with a tough constitution, make for one of the best and most popular native ground covers for easter U.S. gardens. Its variety collina is a clumper rather than a runner, so it’s a better choice where a less rambunctious ground covering plant is required.

Barren Strawberry

Semi-evergreen leaves and bright golden spring flowers make this handsome bee plant a real winner in the garden.

Dense swaths of strawberry-like leaves expand steadily and tenaciously to provide attractive semi-evergreen ground cover in most any garden niche, from dry shade to full sun. Saucer-shaped yellow flowers dot the plants in spring, with a few repeat blooms later on. Recently moved to the genus Geum, barren strawberry (Waldsteinia fragarioides aka Geum fragarioides) is one of the best native ground covers for eastern U.S. gardens – under whatever name.

Persimmons and Paw Paws: Fall Fruits of the Forest

So you want to plant a fruit tree? Something that will fill that blank space in the back yard while supplying your family (and impressing your neighbors) with a bumper crop of juicy, scrumptious munchies? Great idea! Of course, you could always opt for a perfunctory apple or peach (which could all too easily develop into a horticultural and aesthetic nightmare). On the other hand, you could plant a tree (or two) that’s native to the eastern United States, offers year-round beauty, and yields succulent fruits that look and taste as if they came from the tropics.

American Persimmons

American persimmons
American persimmons are bitter until after the first frost when they quickly turn sweet.

Case in point: your backyard (if it’s not too small) could grow real persimmons, produced by the only hardy species in the ebony family. How cool is that! Native from the deep Southeast to southernmost New England, American persimmon (Diospyros virginiana, USDA Hardiness Zones 4-9) is a comely, medium-sized tree characterized by knobbly, deeply grooved, “alligator” bark, large oval leaves, and relatively sparse, often sinuous branches.

American persimmon tree bark
The American persimmon is a large tree with alligator-like bark that looks great in winter.

Of greatest interest to culinary gardeners, however, are its flavorful fruits, which put on a show as they ripen orange in late summer and early fall. A heavily fruiting tree gives the impression of being hung with hosts of miniature pumpkins. Astringent at first, the pulpy flesh sweetens and mellows to an eggnog-like flavor as the fruits mature, reaching their peak as they wrinkle and soften. It makes for good fresh eating, as well as for yummy puddings, pies, and preserves. Far less remarkable are the fragrant, pale greenish-yellow, late-spring flowers, which tend to be exclusively male or female, requiring two trees for pollination and fruiting. Self-fruitful persimmons do occur, though, including ‘Meador’, an exceptionally cold-hardy, prolifically fruiting selection that bears at a relatively young age (typically 10 years).

Paw Paws

Paw Paws

If you’d like a cool tropicalesque native fruit tree in a somewhat smaller size, there’s always the only hardy member of the custard apple family. Paw paw (Asimina triloba, zones 5-9) occurs in the understory of rich woodlands from the mid-Atlantic to the Southeast to the Midwest, typically growing as a gaunt shrub distinguished only by its bold, oblong leaves that broaden toward their tips. But it undergoes a total personality change in sunny or lightly shaded gardens, developing into a small, densely leaved, round-headed tree that brings an equatorial vibe to the temperate landscape. It also produces its large potato-shaped fruits much more willingly in cultivation than in the wild, provided more than one variety is grown.

Paw Paws flowers

The fruit’s relatively thin, pale green to yellow-green rind encloses a fleshy interior that turns yellow as it ripens to a custardy texture in late summer or early fall. Flavor varies from delectable to astringent, with the flesh of most named varieties (such as ‘Susquehanna’ and ‘Sunflower’) possessing a delightful, fruity taste reminiscent of banana, pineapple, or mango. Large, bean-shaped seeds also occupy much of the interior but are typically smaller and fewer in cultivated varieties. Curious, fleshy, purple flowers precede the fruits in spring, adding to paw paw’s singular charm.

Inside Paw Paws
Paw paws, also called custard apples, have sweet yellowish flesh with a custardy, banana-like flavor.

Of brief shelf life (and thus rarely appearing in markets), paw paw fruits are best eaten fresh off the tree, or incorporated into puddings, pies, preserves, custards, and ice cream. The flesh freezes well, making for a mid-winter, fridge-to-table treat. In addition to their delectable flavor, pawpaws also abound in nutrients including vitamin C, magnesium, iron, copper, manganese, potassium, amino acids, riboflavin, niacin, calcium, phosphorus, and zinc. As with American persimmon, pawpaw is a tree — and fruit — of distinction, that will do your yard and table proud.

Planting Persimmons and Paw Paws

Paw Paws in sunlight
Paw paws grow well in a little less sunlight and have large, bold leaves that tend to turn yellow in fall.

Get your new tree off to a good start by planting it in spring or late summer in a hole that’s the same depth but several times wider than its root ball. Backfill with native soil, and mulch with a good compost, such as Fafard Premium Organic Compost, topped by 2 to 3 inches of leaf mold or bark mulch. American persimmon grows well in most soils, but paw paw requires a relatively moist, humus-rich soil for optimal performance. Bon appetit! (Click here to read more about how to site and plant trees.)

What Perennials and Shrubs To Plant in Fall

Summer perennials and potted shrubs are great to plant in fall!

“Perennials (both woody and herbaceous) are shifting energy from their tops to their roots, preparing for their fall underground growth spurt.” -Russell Stafford

Gardeners tend to do the bulk of their planting and planning in spring when the horticultural hormones are running high. For many plants and purposes, however, fall is the perfect time to get down to some serious gardening. The best time, in fact.

Fall Growing Conditions

Fall growing conditions tend to be cool and moist–just perfect for new plantings.

Consider the conditions in fall. Soil and air temperatures are typically moderate, beneficial underground microflora are active, and soils retain moisture longer (thanks to the cooler air and lengthening nights). Plants, too, are undergoing favorable changes. Perennials (both woody and herbaceous) are shifting energy from their tops to their roots, preparing for their fall underground growth spurt. Deciduous plants are shedding their leaves, removing their main source of water loss and drought stress. On all fronts, things are geared for root growth, for as long as soil temperatures remain conducive (above around 40 degrees F).

Plant a hardy tree, shrub, or herbaceous perennial now, and its roots will proliferate (as conditions allow) until spring, gathering energy and preparing for a prosperous new year. Compared to an equivalent plant installed next spring, it will have a far more extensive root system, already adapted to the conditions on (and in) the ground. It will grow faster, tolerate drought better, and in almost every other way out-perform its spring-planted kin.

Bulbs for Fall

Hardy spring bulbs must be planted in fall. (Image by Jessie Keith)

Bulbs (including the rhizomes, corms, etc. that go under this term) are a special case. Most hardy spring-blooming bulbs absolutely require at least a couple of months in chilly, moist soil to stimulate rooting and develop and extend their flower buds. These are the bulbs for fall planting–crocus, daffodils, tulips, and hyacinths are among them. Don’t worry about planting them late, especially if you find bags of bulbs on sale in late October. Bulb planting into late November is just fine as long as you can work the soil. Adding a quality bulb fertilizer at planting time will help them flourish.

On the other hand, some bulbs spend winter in a rootless quiescent state and take well to winter dry-storage and spring planting. Many of the latter are frost-tender things such as dahlias, but the winter-dormant group also includes some hardy “bulbs” such as roscoeas and crocosmias.

Plants You Should Plant in Spring

Balled and burlapped shrubs and small trees should be planted in the spring, not fall.

As with all things horticultural, a few provisos apply. Most of the above advantages are nullified in the case of bare-root or balled and burlapped (B&B) plants, which lose many of their roots during harvesting. With their reduced underground resources, they may lack the capacity to replace water lost from stems and leaves during cold windy weather. Fall-planted bare-root and B&B evergreens are especially prone to winter damage. Severely root-bound container-grown plants do relatively poorly with fall planting, for the same reasons. In contrast, container-grown plants have relatively extensive root systems, buffering them against winter weather.

Fall perennials, like Japanese anemones, prefer springtime planting. (Image by Jessie Keith)

Additionally, some plants that hit their prime in summer and autumn tend to languish if planted in fall, whatever the condition of their roots. Many warm-season grasses and fall-blooming perennials, for example, prefer spring planting. Marginally cold-hardy plants may also benefit from spring planting, which gives them more time to establish before heading into their first winter. Small perennials and shrubs in little pots may also need the headstart of spring planting to grow and set ample roots by fall.

Fall Planting Tips

Make sure that potted plants do not have any congested or girdled roots as this will limit fall root growth.

Planting at least 6 weeks before your last frost date will give perennials and shrubs plenty of time to set new roots (click here to determine your last frost date). Whatever you plant this fall, be sure to provide the conditions for optimal rooting. Dig a planting hole as deep and several times as wide as the root ball. If the soil is excessively heavy or sandy, dig an even wider hole, and generously amend the backfill with Fafard® Premium Topsoil. Tease the surface of the root ball to loosen any congested or girdling roots. After planting and watering your new prize, apply a layer of compost topped with two or three inches of a porous mulch such as oak leaves, pine needles, or shredded bark. This will blanket the roots from drought and cold, extending their season of growth. Come spring, you’ll have a well-rooted plant, ready for takeoff.

*Fall is also an ideal time to divide and plant summer perennials! (Click here to learn more about perennial division.)

Native Hellstrip Gardens

The Highline in New York City is filled with some of the toughest natives for urban hellstrips, such as purple leadplant, native grasses, and coneflowers.

Where there’s a sidewalk, there’s often also a hellstrip – that narrow planting space between the walk and the street. Flanked by baking pavement and blessed with soil composed of compacted sand, construction rubble, and the like, it’s not the most welcoming place for plant life. It also confronts unique challenges such as marauding dogs (and humans), traffic visibility restrictions, and road salt. If a plant is over 4 feet tall or can’t handle even a bit of foot traffic or salt spray, it’s probably not suited for hellstrip duty.

Hellstrips take a beating from heat, pedestrians, and traffic. The fuller your initial planting, the better. (This one looks like it will be under foot in no time.)

As it turns out, quite a few plants native to eastern and central North America are more than up to these challenges. After all, environmental conditions in coastal sand dunes, dry prairies, rocky slopes, and numerous other native habitats can get every bit as hostile as those in your typical hellstrip.

To give your hellstrip border a strong overall visual structure, dot it with shrubs and large perennials planted singly or in small groups. Then fill in the gaps with smaller plants, including generous groupings of ground-covering perennials. In future years, edit seedlings and offshoots as desired.

Native Plants for Hellstrips

Butterflyweed (Asclepias tuberosa)

Butterflyweed feeds monarchs and other butterflies and will withstand hellstrip conditions.

Monarch butterflies in your neighborhood will flit with joy if you stud your strip with clumps of this tap-rooted, 2-foot-tall perennial. Native to dry sunny meadows and prairies of Central and East North America, butterflyweed (Zones 3-9) will take as much sun and drought as nature throws at it, answering with an early summer display of orange-red to yellow flowerheads. You’ll likely have even more of it next year, thanks to self-sown seedlings. Lots of other drought-tolerant Asclepias are well worth seeking out and growing – especially the spectacular purple milkweed (Asclepias purpurascens, Zones 4-9). It does indeed produce rich rose-purple domes on stems that are taller than those of butterfly weed (to 3 feet or slightly more). As an ornamental, it’s far superior to its vaguely similar cousin common milkweed (Asclepias syriaca), which has duller flowers and a much more invasive habit (and is best avoided unless you want your border to be ONLY common milkweed).

Twilight aster (Eurybia × herveyi ‘Twilight’); heath aster (Symphyotrichum ericoides)

Heath aster provides good green cover in summer and lovely white fall flowers.

A hybrid of large-leaved aster (Eurybia macrophylla) and showy wood aster (Eurybia spectabilis), ‘Twilight’ (Zones 3-4) spreads relatively rapidly into ground-covering foot-tall swards clothed with narrowly heart-shaped leaves. Thirty-inch stems decked with pale lavender flowers arise in summer, with bloom continuing from early August into fall. A first-great ground cover for drought-prone partially shaded borders, it also does well in full sun. Speaking of asters, prostrate forms of heath aster (Zones 3-9) and its kin can hardly be bettered as ground covers for hot sunny hellstrips. With their needle-like foliage, they do indeed resemble a heath or heather, until their clouds of small daisy flowers open in late summer. The carpeting, white-flowered cultivar ‘Snow Flurry’ is indispensable for covering ground or cascading down a wall.

Coneflowers (Echinacea and Rudbeckia)

Rudbeckia triloba with swarms of relatively dainty burgundy-and-yellow “black-eyed Susans” in summer.

Purple coneflower (Echinacea purpurea, Zones 4-8) and showy coneflower (Rudbeckia speciosa, Zones 3-9) are a bit too salt-sensitive for many hellstrips. Instead, you might want to opt for Tennessee coneflower (Echinacea tennesseensis, Zones 4-9), a somewhat smaller, more graceful, more salt-tolerant take on purple coneflower, with narrow leaves and blunter, horizontal (rather than drooping) petals. The flowers are the usual echinacean purple, in late spring and summer. Its hybrid ‘Pixie Meadowbrite’ is a wonderful little thing with shocks of narrow leaves which give rise to relatively large rose-pink flowers on 20-inch stems. As for rudbeckias, among the best and most adaptable is ‘Prairie Glow’, a cultivar of Rudbeckia triloba with swarms of relatively dainty burgundy-and-yellow “black-eyed Susans” in summer. At 40 inches tall it’s close to being a stretch for a hellstrip planting, but its height is countered by the airy see-through texture of its inflorescences. The somewhat short-lived plants inevitably self-sow.

Robin’s plantain (Erigeron pulchellus)

Can a native lawn weed also be an unsurpassably useful groundcover?

Can a native lawn weed also be an unsurpassably useful groundcover? In the case of the cultivar ‘Lynnhaven Carpet’ (Zone 3-9), the answer is an emphatic “yes”. Large handsome rosettes of broad, fuzzy, gray-green leaves pop up here and there, eventually merging into a weed-smothering mass. It’s adorned in spring with numerous pink daisy flowers on 18-inch stems. Even better, ‘Lynnhaven Carpet’ thrives in just about any soil or sun exposure. Less vigorous but cuter is the Robin’s plantain variety ‘Meadow Muffin’, with congested rosettes of crinkly leaves.

White spurge (Euphorbia corollata)

Dainty white spurge will obligingly seed itself into whatever open patches of soil may occur. (Image by Cody Hough, college student, and photographer in the Michigan area.)

A delightful prairie and meadow dweller that’s ideal for naturalizing among carpeters such as heath asters, white spurge (Zones 3-9) carries flurries of flowers in late spring and summer that give the impression of a tall baby’s breath (Gypsophila paniculata). It’s a much less fussy critter than any gypsophila, however – provided it has ample sun and elbow room for its sparsely branched, 3-foot-tall stems. It will obligingly seed itself into whatever open patches of soil may occur. Numerous pollinators including the rare Karner’s Blue butterfly adore its flowers, and you’ll also love the vibrant orange and red color of its fall foliage.

Gaura (Oenothera lindheimeri)

Gaura is a tireless, heat-loving spring-to-fall bloomer

This tireless, heat-loving spring-to-fall bloomer was profiled a few months back in our piece on perennials that don’t quit. As with many of the other perennials portrayed here, it will seed itself around in any sunny border, giving you plenty of editing opportunities. White-flowered cultivars such as ‘Whirling Butterflies’ are beautiful things, their waving wands of fluttery white flowers making a pleasing complement to echinaceas and other members of the daisy family. You might also want to mix in a pink-flowered variety (look for ‘Siskyou Pink’ and ‘Crimson Butterflies’).

Little bluestem (Schizachyrium scoparium)

Hot sun and sandy poor soil are no problem for little bluestem. (Image by Proven Winners)

We dismiss some highly ornamental and useful plants simply because they’re familiar to us as roadside “weeds”. Such is the case with little bluestem (Zones 3-9), which you’ll see ornamenting hot sunny roadsides across most of the U.S. Yet it has many notable charms, especially in late summer and fall, when its tall plumes of purplish-tan seedheads and its sunset-toned fall foliage put on a show. Several cultivars (e.g., ‘Blue Heaven’ and ‘The Blues’) also stand out in summer with their steely silvery-gray leaves. Another to seek out is the tidy, upright, blue-green Prairie Winds® ‘Blue Paradise’. Hot sun and sandy poor soil are no problem – in fact, they’re its preferred habitat.

Seaside goldenrod (Solidago sempervirens)

Seaside plants such as this goldenrod also grow well on hellstrips.

A plant that naturally grows on sunny seaside dunes and cliffs is ready-made for hellstrip conditions. The mounds of blue-green, tongue-shaped leaves are quietly handsome, and the late summer to fall, 3-foot fountains of sunny flowers are a delight. They’re also a pollinator’s dream (the bumblers, in particular, love them). As with many hellstrip candidates, it actually does and looks best in dry poor soil. It would rather you not pamper it.

Leadplant (Amorpha canescens)

Small shrubs, such as leadplant (Zones 3-8), also have a place in hellstrip plantings. The common name of this 2- to 3-foot shrublet refers to its tolerance of metal-laced soil – and it’s similarly disposed toward road salt. A pulchritudinous prairie native that would flatter any garden, it features ferny pinnate gray-green leaves adorned in early summer with feathery spires of purple-blue flowers.

Chokeberry (Aronia melanocarpa)

White spring flowers, edible fruits, and fine fall foliage are some of the benefits of chokecherries.

Offering showy white flowers in late spring, edible black fruits in midsummer, and gleaming rich green foliage that goes fiery in fall, compact varieties of this widespread native Aronia (Zones 3-9) are excellent shrubby choices for sunny to partly shaded hellstrips (did we mention that it’s also remarkably adaptable?). Selections include 3- to 4-foot ‘Iroquois’ and the even smaller ‘Low Scape Mound’ (which tops out at 2 feet).

New Jersey tea (Ceanothus americanus)

New Jersey Tea feeds pollinators and performs very well in hellstrips.

Here’s another splendid small shrub native to sunny arid habitats in the central and eastern U.S. Its 3-foot stems are covered with frothy white flowers in late spring and early summer, as well as with pollinating butterflies and bees. New Jersey tea (Zones 3-9) also tolerates moist soils.

Planting A Hellstrip

This hellstrip garden in Portland, Oregon. (Mike Darcy)

Late summer and early fall are a great time to plan and plant your own native hellstrip border. So why not get to it? If the soil is extremely compacted, sandy, or otherwise plant-habitat-challenged, you might want to fork in a couple of inches of Fafard Premium Natural & Organic Compost or apply it to the surface after planting. Even if you don’t, you’ll find that most of the plants portrayed here will manage to get by in all but the most extreme circumstances. You may sometimes find yourself wondering whether they’re native to the moon, rather than to the North American region of this planet. These babies are tough.