The Best Reblooming Shrubs for 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
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
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
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.
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.
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.
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.
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.
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