Plant enthusiasts have a tendency to use language rather floridly, if you’ll pardon the pun, when they describe their favorite plants. But hydrangeas are one of those species were the word “remarkable” is truly no exaggeration. How many plant families do you know of that can trace their history back 70 million years, are native to three continents, contain members that are bushes, trees and vines, are both deciduous and evergreen, and whose flowers can completely change color from year to year? Not to mention that fact almost all are extremely hardy, easy grow and tolerate both full sun and part shade. There really is a variety of hydrangea to suit any garden, from clay pots to cultivated acres, and now early summer, is their time to shine.
From the average gardener’s perspective, the only real problem with the hydrangea family seems to be that it is too large for many people to get a good grasp of. The genus is actually divided into at least 8 sub-sections, which are further divided into at least a dozen species and hundreds of cultivars. I say “at least” here pointedly, because there are so many different kinds of hydrangeas that even the botanical nomenclaturists are in disagreement. Fortunately for the home gardener, the most common types of hydrangeas seen in the nurseries today belong to only five species: macrophylla, paniculata, quercifolia, anomala and arboresens, and from each of these I’ve selected one or two varieties that I think are real knockouts in the garden.
Hydrangea macrophylla ‘Endless Summer’
The macrophyllas, often called somewhat erroneously the Lacecap Hydrangeas, are the species that most people think about when they think of hydrangeas. Native to the warm temperate maritime climates of eastern Asia, these are the potted plants you often see in the florist shop. “Endless Summer’ though, is a more robust recent cultivar, and one I include in almost all the gardens I design. Flowering continuously with large, pale blooms from early summer, this wonderful shrub will grow quite big if given the moist, mild (hardiness zone 5 or warmer) dappled shade it loves. The macrophyllas are also the species with the famous color changing trick. In acid soil (pH 6.5 or less) the bloom is blue: add a little lime, and presto, subsequent blooms will turn pink. The heads are also excellent for drying, turning a lovely dusky hue.
Hydrangea paniculata ‘Limelight’
Also know as the Pee-Gee Hydrangea, Hydrangea paniculata is a common site in many parts of the country, especially the cultivar ‘Grandifolia’ which was introduced by the famous plant explorer Siebold in 1869. Recently however, there have been many new introductions, and the most spectacular of all is possibly ‘Limelight’ which blooms with huge, chartreuse blooms which slowly fade to pink in the fall. Interestingly, what we refer to as the flowers on this and all other hydrangeas are actually modified decorative leaves called sepals. The true flowers are almost unnoticeable, buried inside the massive bloom heads, which incidentally on ‘Limelight’ are famous for their drying ability. H. paniculata is extremely hardy (Zones 3/4) and unlike its cousins, prefers full sun.
Hydrangea quercifolia ‘Snow Queen’
This is one of my favorite members of the hydrangea family, and unfortunately, one of the least known. The name, quercifolia, means “oak-leaved” in Latin, and the epithet is apt. The large oak-like leaves emerge fairly late in the spring, followed in mid summer by large panicles of creamy white flowers 6-8 inches long. Like most other hydrangeas, this one requires a constant supply of moisture; given extended periods of dryness, most hydrangeas will wilt miserably. But unlike its relatives, this beauty will take a considerable amount of shade, and for that reason I like to use Oak-leaved Hydrangeas in the landscape as backdrops to hosta, astilbe, and other shade loving plants. Hardy to Zone 5, Hydrangea quercifolia has the added benefit of lovely fall color — the leaves turn purple-red and remain on the plant for quite a long time. Other cultivars of note are “Harmony’ and ‘Snowflake,’ both of which seem to be slightly less hardy, but have the advantage of larger, more showy flowers. Also, for smaller gardens, try the dwarf, ‘Peewee’.
Hydrangea arborescens ‘Annabelle’
This is a stellar plant, and one that should be in almost every landscape. Growing between three and five feet high, this American native is absolutely covered in huge white balls of flower in June, some up to 12 inches wide. In fact this generosity in flower may be its only flaw — ‘Annabelle’ is so floriferous that the huge blooms will often weigh down and occasionally snap the branches after a heavy rain. This cultivar also has the added benefit of reblooming, if the first round of blossom is removed when spent. Preferring morning sun and afternoon shade, ‘Annabelle’ requires a moist, though well-drained, spot with reasonably high fertility to produce the best show. Hardy from Zones 3-9, this shrub is perfect for mass plantings on the edge of the woods or lawn.
Hydrangea anomala subsp. petiolaris
This climbing member of the hydrangea family is probably one of the best all-around vines for the home landscape. The lustrous, dark green leaves are the perfect background for the large, fragrant white flowers which open in June and July and last for over a month. Tolerant of sun or shade, Climbing Hydrangeas ascend by twinning, making them idea for growing up the side of a trellis or tree. Left on their own, the vines can reach 80 feet: in bloom, they are an almost unimaginably beautiful sight. Virtually pest free, the only drawback to this species is that is it almost painfully slow to get started: the first few years the plant seems to hardly move at all, and then suddenly, the growth is exponential. Originating in China and Japan, the Climbing Hydrangea is hardy from Zones 4-8.
Sidebar: Drying Hydrangea Blossoms
Hydrangea blooms are extremely easy to dry, and make spectacular wreaths and arrangements, as long as a few simple rules are followed. Here in Southborough, I harvest the blossoms of H. quercifolia and H. paniculata for winter arrangements. In both species, as the flowers mature, they change color slowly from creamy white to a wonderful pinkish chartreuse — this signal is the key to successful harvesting. Cut while white, the blooms will wilt; wait till the flowers take on a pale pink hue. Hydrangeas will often bloom well for several years, and then flower production will diminish. If you find your bush is producing few flowers, the solution is to prune it back heavily in the very early spring before the leaves emerge — small specimens can be cut back to within 6 inches of the ground and fertilized heavily with rotted manure or 10-10-10. As hydrangeas bloom solely on new wood, the flush of new growth will produce an abundance of bloom later in the season.