Hydrangea time

Sunday, 21 November 2010

Hydrangea quercifolia

The genus Hydrangea is one of the stars of the November garden and with all the rain we have had in spring, they are particularly beautiful this year. Last November, I wrote a blog about Hydrangea macrophylla, which includes most of the types we see in our gardens in Sydney, but there are other less common species that grow quite well in our climate, including Hydrangea quercifolia, the so-called oak-leaved hydrangea. I have the basic species of this shrub in my own garden and at the moment it is covered with its large creamy-white sterile flowers mixed with tiny fertile flowers, reminiscent of the look of the 'Lacecap' group of Hydrangea macrophylla. However, these are held in long, graceful conicals, quite different from the rounded flower heads of Hydrangea macrophylla. They look rather like the blooms of Hydrangea paniculata, a lovely species which does not seem to do well in Sydney, so this is a good substitute.

Hydrangea quercifolia Pee Wee in the garden of Pamela and Harry Fowell in Sydney

The flowers may become pink-tinged as they age. They eventually become papery and brown, still attractive in autumn. The deeply lobed leaves are quite reminiscent of those of an oak tree, again quite different to the more commonly encountered Hydrangea. It is semi-deciduous, the leaves sometimes colouring a little in autumn - more so in colder areas and if grown in a sunny position. It grows to about 1.5-2 m in height. The provenance of this shrub is quite different to most Hydrangea species, which come from Asian areas - it hails from the south-east of USA.

This species need minimal pruning. I trim off the deadhead eventually in late winter, along with any wayward or damaged stems. It seems to grow from underground stolons, which can be detached to grow new shrubs: mine was grown in this way from a friend's shrub many years ago. I haven't ever found it to be invasive. It copes with drier situations than Hydrangea macrophylla (and actually needs well-drained soil) and also tolerates more sun.

Hydrangea quercifolia Sikes Dwarf in the garden of Pamela and Harry Fowell in Sydney

There are a number of named cultivars of this Hydrangea and I was fortunate to be able to see some of these in a nearby garden this week. Some of these are smaller-growing ones, suited to more compact spaces, including 'Sike's Dwarf' (ht 1 m) and 'Pee Wee' (ht 1 m) - they have the same lovely trusses of flowers, but on a smaller scale than the species.

Hydrangea quercifolia Snowflake in the garden of Pamela and Harry Fowell in Sydney

At the other end of the height spectrum is 'Alice', which grows to 2.5 m in height and needs plenty of space to be seen at its best. I was utterly mesmerised by a double-flowered form, called 'Snowflake' - a truly exquisite flower. There are a few double-flowered versions of Hydrangea macrophylla and these are also very desirable plants.

Hydrangea quercifolia Little Honey in the garden of Pamela and Harry Fowell

Yet another variation is one with gold foliage, called 'Little Honey', with the same sort of flowers as the others. The flower heads of oak-leaved Hydrangea are good for picking for vases.These Hydrangea specimens look very attractive grown in shady parts of the garden to create an easy-care 'woodland' effect, along with shrub, cane and rhizomatous Begonia, Justicia carnea, Solomon's seal, Arthropodium cirrhatum and Acanthus mollis, which are all blooming now. They also look effective grown with ferns. The smaller versions of Hydrangea quercifolia can be tried in pots.