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Hydrangeas
by Des Kennedy
by Des Kennedy



Des Kennedy is a celebrated public speaker, having performed at numerous conferences, schools, festivals, botanical gardens, art galleries, garden shows and wilderness gatherings in Canada and the U.S. His humour, irreverence and passion for gardening and the natural world have made him a 'must see' speaker in demand across the country.


October 13, 2002

I've recently returned from a tour of Irish gardens and one of the outstanding features in gardens great and small was the display of hydrangeas. Glorious hydrangeas planted many years ago and blooming in vivid blues, pinks and mixtures of the two. Glorious in the eyes of some, that is, but not all. The enormous mop-head flowers of ‘Hortensia’ hydrangeas, H. macrophylla, an omnipresent shrub in Ireland as well as in Canadian west coast gardens, are the objects of both inordinate pride and derisive scorn, depending upon one’s circle.

In colder parts of Canada, the same dichotomy of enthusiasm greets the peegee hydrangea, H. paniculata grandiflora. It too is at its finest this time of year as its long panicles of creamy white flowers age into a stunning pinkish bronze. Vigorous, dependable and appealing to some people, the peegee is dismissed in Wyman’s Gardening Encyclopedia as “far too common a plant in American gardens.”

Perhaps so. But three times I’ve attempted to get a peegee established at our place, all without luck. Although hardy to zone four and vigorous growers to seven metres or more, this is one commoner that seems a bit too particular for our methods. Other forms have done far better for us, and the beauty of hydrangeas is that different species and varieties, once established, can provide a succession of strong presences in the garden from early summer through early frosts.

One of the first to bloom, often by mid-June, is the climbing hydrangea, H. petiolaris. Native to Japan and Korea and hardy to zone four, in maturity this climber makes an astonishing display. Clinging with rootlike holdfasts, it can climb twenty metres up a tree, producing abundant clusters of white lace-cap flowers. Requiring a cool, moist root run, it’s an excellent choice for a north-facing wall or to cover an old stump or waste ground. Not a plant for small spaces, it can be controlled somewhat by pruning.

Even hardier, to zone three, the smooth hydrangea, H. arborescens, is native to the eastern U.S. Flowering from June to September, it produces round heads of greenish ivory flowers that inspire the common names ‘Snowhill’ and ‘Hills of Snow.’ We’ve got a newer selection named ‘Annabelle’ that’s pleasant enough but rather languid and perhaps a trifle melancholy in its growth habits.

The same can’t be said for our villosa hydrangeas. Native to China and Nepal, they’re robust customers that can grow up to four metres high with large pointed leaves and thick stems, both flushed with red and felted with soft hairs. Best in dry soil and shade, hardy to zone five, the villosa produces large flat-topped clusters of flowers in white, pale pink or purple. The ones at our place have an appealing cast, ivory washed with antique pink.

Villosas tend towards legginess, and we’ve underplanted them with lace-cap forms of H. macrophylla. These come in blues, pinks and whites, all of them lovely. Lace-caps are composed of clusters of small fertile flowers surrounded by larger sterile flowers. We’ve recently added a blue-flowered form of ‘Mariesii’ that has striking white-variegated leaves. Particularly valuable as we tumble into autumn is the oak-leafed hydrangea, H. quercifolia. This is a ruggedly handsome shrub native to the south-eastern states. It’s prized as much for its foliage as for its flowers which appear in midsummer as large trusses of creamy white gradually blushing pink with age. Resembling large oak leaves, the foliage is dark green with felted undersides,and colours beautifully as fall progresses. Like most hydrangeas, these are happiest in semi-shade with lots of moisture and humus. They’re hardy to zone five, and last year I saw several lovely specimens thriving in the Royal Botanical Gardens near Hamilton.

Most hydrangeas are laughably easy to propagate by cuttings, some by division. Theafter they’re relatively trouble-free, although powdery mildew can be a problem in some areas. The primary challenge facing the hydrangea grower is how to prune the shrubs so they hold their shape without becoming overcrowded and failing to flower freely. The pruning regime differs for shrubs that flower on last year’s wood, like macrophylla, and those that flower on new shoots, like the peegee and arborescens. For those that flower on old wood, pruning is done immediately after flowering. The oldest branches are shortened or cut out altogether. If necessary, the weakest of the new shoots are also cut away. Cuts should be made just above strong side branches With forms that flower on new shoots, pruning is done in late winter or early spring, before buds break. Here the old wood is retained as the shrub’s basic framework, and last year’s shoots are pruned back to two or three buds, each of which will produce a strong new flowering stem.

Hydrangeas are also among the choicest materials for dried flower arrangements. Peegees, macrophylla, and arborescens all dry beautifully. Gathered in September, they’ll hold their shape and colour simply by being hung upside down in a cool, dry place. Thereafter they’re exceptional, particularly played against airy sprays of gypsophila or sea lavendar.



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