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Mass Appeal

Martha Stewart Living, August 2007

When Martha Stewart first revealed her passion for hydrangeas in 1994, her readers did a double take. Until then, many people viewed hydrangeas as blowsy shrubs marooned on beach-house lawns or garish foil-wrapped gift plants clogging supermarket aisles in the weeks before Easter and Mother's Day.

The realization that these horticultural faux pas could yield ravishing bouquets or become stars of the late-summer border came as a shock. But once skeptics opened their eyes to hydrangeas' intricate beauty, abundant summer-into-fall bloom, and obliging tolerance of some shade, they began to wonder how they had lived without them for so long.

Infatuation grew into a serious romance, one that has matured despite the occasional heartbreak of frozen flower buds, unkind pruning, and pink petals that stubbornly refuse to turn blue. Fortunately, with the right plant and a little patience and care, the first two problems are often avoidable; as for the third, willful color changes can be embraced as charming eccentricities.

Although no plant promises eternal bliss, recent breakthroughs in breeding have yielded a multitude of new reasons to fall in love. The enormous range available today amazes shoppers who remember garden centers a decade ago, when labels read simply "pink hydrangea."

Now even mass-market suppliers offer climbing hydrangea (Hydrangea anomala ssp. petiolaris) and multibranched H. quercifolia, with its unusual lobed foliage-source of its alias, "oak-leaf hydrangea that turns russet or burgundy in autumn. Specialty nurseries entice sophisticates with a host of nonfloral attributes, such as variegated leaves and stems in striking shades of red and black.

Still, nothing trumps gorgeous flowers, and the current palette stretches far beyond the pastels of yesteryear. Mal Condon and Frank Dutra, of Nantucket Hydrangea Farm Nursery in Massachusetts, which stocks close to three hundred varieties, report that customers are increasingly dipping into less common tonesindigo, reds, electric purple, violet, and lime green.

Besides the familiar mopheads, lacecaps, and panicles (as in H. paniculata), hybridizers have devised novel flower clusters that evoke snowflakes, cascades, even water lilies. Breeders have also made great strides in mildew resistance and hardiness and developed sturdy stems that don't flop in the rain, as well as compact shrubs ideal for a border

Top honors for talent-spotting go to horticulturist Michael A. Dirr, author of the invaluable "Hydrangeas for American Gardens" (Timber Press; 2004). He played a leading role in the greatest recent sensation: cultivars of H. macrophylla that bloom on new growth-ensuring summer flowers even if frost zaps older buds. As a bonus, Dirr's star, 'Endless Summer,' and other members of this group flower a second time. Experimentation with these remontant, or "reblooming," hybrids seems likely to pass along their staying power to less robust varieties. But who cares if the perfect match for your garden has yet to be made in heaven (or a greenhouse)? Some hydrangea that's already out there can't wait to win your heart.

Pretty in Pink or Blue
Despite some hydrangeas' habit of changing color, their tone is harder to tinker with than folklore would have it.

Absorption of aluminum, a mineral naturally present in many soils, can influence the flower hue of H. macrophylla and H. serrata. This process is directly affected by a soil's pH level (the measure of acidity or alkalinity). Acidic soils (pH 0 to 7) tend to deepen blue shades, whereas alkaline environments (pH 7 to 14) brighten pinks and reds. Check your soil with a simple test kit available from nurseries. To acidify soil for "blueing," add aluminum sulfate or peat moss; to enhance a rosy blush, add lime. However, these stratagems rarely produce dramatic, lasting results outside a container or raised bed, and excessive chemical additives may injure the plant. Let a hydrangea show its own true colors and you won't be disappointed.

Making the Cut
Encouraging blooms is the usual aim of pruning, and knowing the species of a particular variety is the key to success. When in doubt, don't prune: This will not impair the plants health.

H. arborescens and H. paniculata: Both bloom only from buds on new stems produced during the current growing season. In late winter, clip the previous year's stems to about 6 inches, or leave more "old wood" to support flower-heavy new stems.

H. macrophylla and H. serrata: These species form flower buds during late summer and fall, but the buds do not open until the following summer. Prune shrubs in late winter or early spring by removing only stems that flowered the previous summer, leaving those with unopened buds intact. Remontant, or "reblooming," H. macrophylla cultivars (such as 'Endless Summer,' 'David Ramsey,' 'Decatur Blue, 'Oak Hill,' and 'Penny Mac') flower on both old and new growth, so no pruning is required.

H. quercifolia: Blooms on old wood; remove only dead branches and flowers.

Staying Power
Walls shelter H. macrophylla 'All Summer Beauty,' from winter wind, which can kill flower buds formed the previous season. H. arborescens 'Annabelle,' above, puts on a grand show, despite hard winters and late frosts, because its blossoms emerge from new stems. Both the mophead, above left, and lacecap, left, flowers of H. macrophylla may be cut for drying or arranging in June and July without thwarting the growth of buds for the following year's blooms.

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