Botanical Information for Oakleaf Hydrangeas
Plant taxonomy classifies oakleaf hydrangeas as Hydrangea quercifolia. This is a case where the Latin genus name is so widely used that it really doubles as a common name.
An example of a cultivar of this plant is 'Snow Queen,' a name that refers to the white flowers produced by the plant during the summertime (it is often confused with 'Snowflake,' which is preferred by some growers, since it has double flowers).
The current article is mainly about Snow Queen, but those who garden in small spaces may be interested in the fact that another cultivar, 'Ruby Slippers,' stays more compact (3-4 feet tall, and with a similar spread). Its smaller size is not surprising when you learn that one of its parents is named 'Pee Wee' (its other parent is Snow Queen), a bush that grows 3-4 feet tall by about 3 feet wide. The flowers of Ruby Slippers age to a reddish color (thus its cultivar name).
Oakleaf hydrangeas are classified botanically as flowering deciduous shrubs.
Traits of 'Snow Queen'
In summer, Snow Queen oakleaf hydrangea flowers in clusters, and the white flowers fade to a pinkish-brown in fall. Their floral display is very long-lasting. But the plant's best-known trait is its oak-leaf-shaped foliage. The leathery leaves are large and turn purple, orangey-bronze, or red in the fall, making the plants great picks for autumn color.
These shrubs routinely achieve a height of 4-6 feet and a spread of 4-6 feet, but they can grow to be larger than that. They are multi-stemmed shrubs, and the branches can shoot out from the center in any direction. Peeling bark offers some winter interest, as well as spring interest (before the plant fully leafs out in the spring, there is little visual interest outside of the bark).
Planting Zones, Sun and Soil Needs
H. quercifolia 'Snow Queen' shrubs can be grown in USDA planting zones 5-9. The species plants are native to the southeastern United States.
Oakleaf hydrangea shrubs are understory plants in the wild. So, in the South, give them afternoon shade. In the North, oakleaf hydrangeas can get by with less shade. Too much shade, in fact, may reduce the intensity of their fall foliage color. Grow them in a well-drained soil with a slightly acidic soil pH and plenty of compost. The more sunlight they get, the more you should be watering them.
Plant Care (Pruning), Uses in Landscaping
Oakleaf hydrangea shrubs usually require little pruning, unless you are trying to fit them into a location that is really too small for them. In such cases, you may want to re-think your plant selection for that spot and simply transplant your Snow Queen to a location where it has more room to grow.
But sometimes, even if you have chosen the right location for the bush, you may be forced into pruning it. For example, you should prune if the plant suffers damage (for example, from winter die-back). To prune in a case like this, when spring comes, cut the affected branches down to just below where the damage happened.
If you do wish to prune because you are trying to control the plant's size and/or shape, do so right after the blooming period, since this type of bush blooms on old wood. Mulch your bushes to keep the roots cool in summer, especially in hot regions.
With their brilliant fall foliage and long blooming period, oakleaf hydrangea shrubs are attractive enough to function as specimen plants. As understory shrubs in the wild, they are also appropriate in woodland gardens. Their big leaves give them a coarse plant texture, useful as a contrast with plants of a more delicate texture. The dried flowers are used in crafts, while the fresh ones make for good cut flowers.
Best Feature of 'Snow Queen' Oakleaf Hydrangeas
Truly shrubs with year-round interest, these bushes clearly belong on any list of great plants that beginning gardeners generally do not know about.
While the shape of their leaves is the feature that gives them their name, their fall foliage color is the best feature of oakleaf hydrangea bushes. Grow them in addition to your most colorful trees for fall, thereby giving your yard good fall color at more than one eye level.
Their second best feature may well be their long "blooming" period. The reason that the word, "blooming" is placed in quotes is that it is not actually petals that are anchoring the floral display, but rather something known as "sepals." Sepals are like petals, but they are sterile. Since they can't be pollinated, they can't go to seed. Playing no part in the reproduction process, they are free to just "hang out" and give your yard color all summer long. The true flowers on oakleaf hydrangeas are those tiny ones that you see behind the sepals if you look very closely.
Word Origin for Oakleaf Hydrangeas
How does the scientific name, Hydrangea quercifolia break down, exactly? Well, we are all familiar with the Greek root hydr- as a reference to water, as in "hydrate." Meanwhile, angeon comes from the Greek for "vessel." Some people apparently see a resemblance between a hydrangea seed pod and a water vessel. Most species do require a lot of watering (oakleaf hydrangeas often need a bit less water than some other kinds, though).
As for the species name, quercifolia literally means "oakleaf" in Latin. This explains the common name, too: The leaves look like those found on oak trees.