Big, bold, and showy hydrangeas

Easy-care shrubs thrive in the shade

When I was a novice gardener, I didn't like hydrangeas; I found them, shall we say, Rubenesque. So I filled my shade garden with delicate, airy flowers and lacy foliage: columbines, bleeding hearts, ferns, sweet woodruff.

Then one day, I looked around and noticed that my garden was too detailed. I had soulful little vignettes everywhere, but nothing bold on which to rest the eye, no effects that could even be seen several yards away. Besides that, all the flowers were over by early summer.

That's when I started to appreciate hydrangeas.

Hydrangeas are among the few plants that provide big, showy flowers and bold-textured foliage in the shade - and in summer to boot. They are also easy-care, long-lived plants.

The genus includes several different species. Although they share a preference for moist, lightly shaded sites, hydrangea species vary in size, flower shape, sun-tolerance, and cold-hardiness.

Most familiar are the mophead varieties of bigleaf or garden hydrangeas (Hydrangea macrophylla) - big, round shrubs with flower balls in blue or pink. Because this species has been used in landscaping for decades, we tend to associate it with grandmothers, Victorian mansions, and seaside resorts.

This stalwart, which can grow 6 to 8 feet high and as wide, looks best in large settings with plenty of breathing space around it: on a large, shady lawn, say, with a backdrop of tall trees, or as a hedge at a property boundary.

The big, splashy flowers have impact even from a distance. And their colors are luscious. These flowers are famous for changing from pink or rosy-red in alkaline soils to blue in acidic ones; they're frequently soft shades of lavender or pink and blue together in neutral environments. (See box for tips on changing flower colors.)

There are many wonderful cultivars of Hydrangea macrophylla. Mike Foran, owner of Hydrangea Plus nursery on New York's Long Island, recommends Mousseline, a medium-size shrub with flattish flower heads 12 to 14 inches across, in colors ranging from apple pink in alkaline soil to grayish-blue in acid soil. "Grayish blue doesn't sound that nice," says Mr. Foran, "but this is a kind of pearly color, really fantastic."

He also likes Brestenburg for its "deep, British green, serrated leaves" and flowers that range from bubble-gum pink to deep purple. "It's a good-looking, rounded shrub with rigid stems, not intimidated by the weather," Foran says, "and can take more sun than most."

Garden hydrangea also comes in another flower shape, the lacecap. It's a flat group of tiny, fuzzy flowers surrounded by a ring of larger flowerets, like a lace doily or pinwheel.

The colorful, central flowers are the fertile ones that work for the plant; the larger outer flowers are sterile. This form is decidedly graceful, intriguing to look at up close and also effective from a distance: The lacecaps alternate with the green leaves in a regular pattern, like stylized clouds in a Chinese painting. Lacecaps also change color between blue and pink, depending on soil.

Bigleaf hydrangeas do best with morning sun and light afternoon shade, Foran says. Native to woodlands in China and Japan, they prefer soil enriched with organic material, and the relatively temperate climate of Zones 6 to 9.

Their cousin, Hydrangea serrata, is a smaller, more cold-hardy, less sun-tolerant shrub, which originated in Japan and Korea. Hardy in Zones 5 to 9, they usually top out at 4 feet and have narrower, serrated leaves. Their flowers come in mophead and lacecap forms, too, and also change color, although differently from bigleaf hydrangeas.

I'd heard that the cultivar Preziosa came in glowing shades of rose, so I was shocked when the first flower I saw opened pure white. By the next day, however, it was pale pink, and every day thereafter it darkened, until finally the flowers were the deep rose described. This is typical.

Hydrangea sargentiana and Hydrangea aspera are less-familiar Asian species that are hardy only in Zones 7 to 9; they seem to do best in the Pacific Northwest. These are large, striking shrubs with velvety leaves and lacecap flowers in shades of pink and mauve.

Until recently, the American species of hydrangea have taken a back seat in gardens to the Asian varieties, but with the current interest in native plants, this is changing.

Smooth hydrangea (Hydrangea arborescens) is our native woodland hydrangea, a versatile 4-foot shrub hardy from Zones 4 to 9 (i.e., in most of the continental US), and able to tolerate conditions from deep shade to full sun, if given enough water. (It prefers half sun.)

A form of the species with white, lacecap flowers and silver-backed leaves is available. But most commonly seen are the cultivars Annabelle and Grandiflora, known for their extraordinarily large flowerheads - slightly flattened, foot-wide globes of flowerets that open greenish, mature to white, and finally dry to beige.

If rain knocks the top-heavy flowers to the ground, this can be a messy-looking plant. But in full bloom, it is so strikingly white it has been nicknamed "Hills of Snow."

Hydrangea quercifolia, oakleaf hydrangea, which is native to the southeastern US, is one of the world's great plants.

Landscapers go wild over its combination of bold texture and changing colors. This hydrangea's lobed leaves give it a hearty, craggy look; it stands out from daintier plants in a border like wheat bread from white rolls.

Its flowers, arranged in stiff cones, open creamy-white in early summer, then darken to pink, rose and finally tan in fall and winter.

Meanwhile, the green leaves turn red, purple, and bronze in fall. In winter, the flower skeletons whisper in the breeze (while they last), and the plant's stems, with exfoliating (peeling) bark, also add interest to the garden. This is an impressive and changeable plant all year round.

Oakleaf hydrangea grows to six to 10 feet tall; although a dwarf cultivar is now available, to my mind the large leaves and flowers look awkward on a small plant; this one should be Rubenesque. Hardy in Zones 5 to 9, it prefers morning sun and afternoon filtered shade.

Hydrangea petiolaris is a climber, a massive clinging vine that can reach 80 feet tall.

It's elegant and memorable in full summer bloom with foamy-white lacecap flowers and glossy green leaves. It prefers a shady site and is so heavy and woody that it requires a sturdy support. This Asian native is hardy to Zone 4.

Hydrangea paniculata is a shrub that can grow to 25 feet. I didn't realize at first that the small tree in the shady yard down the street was a hydrangea.

It had a thick, gnarled trunk and a mass of tangled branches with panicles of white flowers. The flowers darkened to pink in summer and faded to beige in fall. It requires pruning to tame the rampant tangles, but this is possibly the most cold- and sun-tolerant of all hydrangeas.

Peegee hydrangea (Hydrangea paniculata 'Grandiflora') has drooping flower panicles; Tardiva blooms in late summer, and its panicles are upright. This species prefers full sun, tolerates light shade and is hardy in Zones 3 to 8.


How to change hydrangea flower colors

Gardeners can change the color of Hydrangea macrophylla flowers by adding chemicals to the soil. Mike Foran of Long Island's Hydrangea Plus suggests adding 1 tablespoon of aluminum sulfate and 1 tablespoon of Miracid (both from a garden center) to a gallon of water

Both chemicals are needed, he says, because the plant won't take up one unless the other is also present. Pour one-third of the mixture on the soil, wait 20 minutes; pour the second third, wait 20 minutes, and pour the last third. Do this once every 30 days from when buds appear in spring until flowering.

It can take four to six months to change the color from one extreme (true blue or pink) to the other. Foran warns that aluminum sulfate can burn roots, so don't use more than the recommended amount. Also, don't breathe this chemical or get it on your skin.

(c) Copyright 2001. The Christian Science Monitor

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