Archive: Apr 2018

  1. Growing Scented Geraniums

    Citronella-scented geranium deters mosquitoes.

    In the centuries before sewers and daily bathing were common, rank odors were everywhere.  That is probably why Europeans were so excited when scented geraniums (Pelargonium spp.) first arrived from their native South Africa in the early 17th century. With aromatic leaves exuding the fragrance of roses, citrus, or spice, the plants were immediately pressed into service as weapons in the ongoing battle against undesirable smells.

    Scented Geranium History

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  2. The Best Reblooming Shrubs for Summer

    Panicle hydrangea blooms through much of the summer.

    Flowering shrubs do lots of good things in the garden, but their length of bloom often disappoints.  Exceptions do occur, with hybrid roses being the most obvious and ubiquitous example.  They’re not the only shrubs that bloom long and well, though.  Here are seven of the best of the rest.  Their individual flowers may not be as voluptuous as those of a hybrid tea rose, but in other respects – including habit, foliage, and disease-resistance – they more than hold their own.

     

    Littleleaf Lilac and Hybrids

    Littleleaf lilac has smaller blooms that rebloom in midsummer.

    Almost all lilacs are one-and-done bloomers.  Not so with littleleaf lilac ‘Superba’ (Syringa pubescens ssp. microphylla ‘Superba’).  Abundant clusters of sweet-scented, pale lilac-pink flowers open from reddish buds in mid-spring, a few days after those of common lilac.  Then, in midsummer, a miracle occurs, with a second flush of blooms developing on the current season’s growth.  Littleleaf lilac is also attractive out of bloom, forming a dense, rounded, 8-foot specimen clad in dainty, privet-like leaves.  Plant breeders have crossed ‘Superba’ with other lilacs to produce several repeat-blooming cultivars, including those in the Bloomerang® Series.   For maximum rebloom, plant ‘Superba’ and its offspring in full sun and fertile, loamy, near-neutral soil.  A spring top-dressing of Fafard® Premium Natural & Organic Compost is all to the good.  These lilacs do best in USDA Hardiness Zones 4 to 8.

     

    Summer Snowflake Doublefile Viburnum

    Summer snowflake is a reblooming doublefile viburnum. (Image by Russell Stafford)

    Viburnums, like lilacs, typically flower for only a couple of weeks per year.  One of the few exceptions is the remarkable ‘Summer Snowflake’ (Viburnum plicatum ‘Summer Snowflake’), whose terraced branches are frosted with flat clusters of white flowers from mid-spring to early fall.  It also differs from other doublefile viburnums in its relatively compact, narrow habit (5 to 7 feet tall and wide).  Although lacking the wide-sweeping drama of full-sized doublefile cultivars, such as ‘Mariesii’ and ‘Shasta’, ‘Summer Snowflake’ literally makes a better fit for foundation plantings and other niches where space is limited.  The leaves take on smoky maroon tones in fall.  All doublefile viburnums perform best in sun to light shade and humus-rich soil, in USDA Hardiness Zones 5 to 9.

     

    Weigela Sonic Bloom® Series

    Weigela Sonic Bloom® Pink offers bright color through summer. (Image by Proven Winners)

    Many weigelas throw a few flowers now and then in the months following their main late-spring display.  This has inspired plant breeders to develop new Weigela (Weigela hybrids) cultivars that rebloom not demurely, but with abandon.  Those in the Sonic Bloom® Series are reputed to produce several good flushes of showy, trumpet-shaped blooms not just in late spring, but throughout summer and early fall.  Sonic Bloom® weigelas flower in pink, purple, or white, depending on the variety.  These relatively recent introductions have yet to prove their mettle in many parts of the U.S. – but they’re well worth a try in a sunny spot in USDA Hardiness Zones 5 to 8.  At 4 to 5 feet high and wide, they won’t take much space while you’re putting them through their paces.

     

    Caucasian Daphne

    A parent of the variegated, briefly blooming Daphne × burkwoodii ‘Carol Mackie’, Caucasian daphne (Daphne × transatlantica) is in most ways superior to its popular offspring.  Where it particularly outdistances ‘Carol’ is in its repeat, spring-to-fall display of tubular, white, sweet-scented blooms.  The dainty, oval, semi-evergreen leaves are also attractive and are strikingly variegated in forms such as ‘Summer Ice’.  Most varieties of this outstanding daphne top out at about 3 feet tall, with their branches splaying with age (or with heavy snow).  It does well in sun to light shade in USDA Hardiness Zones 5 to 8.

     

    Panicle Hydrangea

    The flowers of ‘Pinky Winky’ panicle hydrangea darken in color as they age. (Image by Jessie Keith)

    Not many years ago, panicle hydrangea (Hydrangea paniculata) was represented in gardens almost exclusively by the mop-headed cultivar ‘Grandiflora’ (more commonly known as peegee hydrangea).  Today, numerous outstanding varieties of this exceptionally hardy species (USDA Hardiness Zones 3 to 9) have found their way into horticulture, including many with lacy, conical flower clusters rather than weighty mops.  Most Hydrangea paniculata cultivars bear white-flowered panicles from mid to late summer, but other flowering times and colors also occur.  Look for ‘Limelight’, with full flower-heads that age to chartreuse-green; ‘Pinky Winky’, an early- to late-summer bloomer that evolves from white to rose-pink; and the late-blooming (and magnificent) ‘Tardiva’, with large lacy spires of white flowers from late summer to frost.  These large shrubs can be cut back severely in early spring to keep them in bounds.  Dwarf varieties such as ‘Little Lamb’ require no size control.

     

    Butterfly Bush

    Sterile, seed-free butterfly bushes are just as pretty but don’t self sow.

    How can we not mention the ever-popular, somewhat cold-tender butterfly bush (Buddleia davidii) and its many hybrids, which draw in butterflies over much of summer with their steeples of fragrant blooms in a variety of colors?  Recent developments in the butterfly bush universe include the introduction of several compact, sterile cultivars with especially prolonged bloom and no pesky seedlings.  These include ‘Ice Chip’, ‘Lavender Chip’, and ‘Purple Haze’.  Buddleia davidii and its hybrids do best in full sun in USDA Hardiness Zones 5 to 9, and usually benefit from a hard early-spring pruning, even in areas where they don’t die back.

     

    Flowering Abelia

    Flowering abelia is a long bloomer that will flower up until frost.

    Popular in the Southeast and Mid-Atlantic regions of the U.S., flowering abelia (Abelia × grandiflora and kin) are small to medium shrubs that could be used much more in the northern fringes of their USDA Hardiness Zones 5 to 9 hardiness range.  Their dainty, fragrant bells – in various shades of pink or white – cluster on arching stems from midsummer into fall.  Small, oval leaves add to the delicate, fine-textured feel of these quietly attractive plants.  Most flowering abelias are evergreen to semi-evergreen into USDA Hardiness Zone 6.   In zones 5 and 6, flowering abelias often work well as winter die-back shrubs, resprouting in spring and flowering in late summer and fall.  In all hardiness zones they benefit from early-spring pruning of snarled or winter-killed stems.

  3. Two Butterfly Garden Designs

    A monarch butterfly feeds on swamp milkweed.

    Everyone loves butterflies, and the threat to monarch populations has spurred increased interest in butterfly gardening. When planning a smart butterfly garden, you want to include plants that feed both adult butterflies and their caterpillars. This is essential because butterfly caterpillars are species specific, meaning they only feed on specific plants.

    Color, design, and site conditions are important when creating butterfly gardens. To make the job easy for new pollinator gardeners, we created two designs that are colorful and appeal to black swallowtail and monarch butterflies. Most butterfly plants are sun-loving, so these gardens are all adapted to sunny garden spaces.

    Black Swallowtail Garden Plants

    A black swallowtail caterpillar feeds on bronze fennel. (Image by Jessie Keith)

    The caterpillars of black swallowtail butterflies feed on many plants in the carrot family, Apiaceae. These eastern North American butterflies have many native host plants, but none are attractive enough for ornamental gardening. Thankfully, quite a few cultivated flowers also feed them. These include bronze fennel, Queen Anne’s lace, lace flower, and dill. When mixed with colorful, compact Magellan zinnias and Sonata coreopsis, which feed adult butterflies, a wild, lacy flower garden is created.

    Black Swallowtail Garden Design: This simple design shows a traditional rectangular flower border, but it can be adapted to fit any garden shape. Just be sure to keep the taller plants towards the center or back of the border. Most of these flowers are annuals, meaning they need to be planted year after year.

    Monarch Garden Plants

    Monarch caterpillars only feed on milkweed plants.

    All milkweed species (Asclepias spp.) feed monarchs. These colorful perennials contain protective chemicals that the caterpillars feed on, which render both the caterpillars and adult butterflies unpalatable to birds. The prettiest of all milkweeds include the orange-flowered butterflyweed (Asclepias tuberosa (USDA Hardiness Zones 4-9)), pink-flowered swamp milkweed (Asclepias incarnata (USDA Hardiness Zones 3-9), and orange-red flowered Mexican milkweed (Asclepias curassavica (USDA Hardiness Zones 8-10)), which self sows yearly. Monarch adults feed on all manner of butterfly flowers. The best are fall-flowering species that support the butterflies as they head to Mexico late in the season, like goldenrod and asters. [Click here to read more about growing milkweeds for monarchs.]

    Monarch Garden Design: This border design includes three showy milkweed species and dwarf late-season asters (such as Symphyotrichum novi-belgii ‘Lady-in-Blue’ (12-inches tall) or ‘Nesthäkchen’ (18-inches tall) and dwarf goldenrod (such as Solidago ‘Golden Baby’ (18-inches tall) or ‘Little Lemon’ (18-inches tall)) to feed migrating monarchs.

    Planting your Butterfly Garden

    These gardens are all designed for full-sun exposures. When planting them, feed the soil with Fafard Premium Natural & Organic Compost to ensure the plants get a good start. You might also consider feeding them with a good flower fertilizer approved for organic gardening. Another important note is to avoid using insecticides, which will damage or kill visiting butterflies.

    These simple gardens are pretty and sure to lure lots of beautiful butterflies to your yard. To learn more about pollinator conservation and gardening, visit the Xerces Society’s Pollinator Conservation page.