How to Grow and Care for Oakleaf Hydrangea

Oakleaf hydrangea (Hydrangea quercifolia) is a flowering deciduous shrub with large clusters of flowers on sturdy stems and distinctive leaves with lobes like those of an oak tree (quercifolia means "oakleaf" in Latin). This shrub is prized for its long-lasting flower panicles that emerge white but gradually transition to purplish pink. Typically growing 4 to 8 feet tall, this multi-stemmed shrub spreads by suckering, and has a rounded upright growth habit.

Oakleaf hydrangea makes a good specimen plant, and it also works well as a foundation plant or when massed in shrub borders or open woodland gardens. The big leaves give these plants a coarse texture, providing contrast with plants with more delicate features.

Fall foliage color is attractive—the leathery leaves turn purple, orange-bronze, or red. The peeling, exfoliating branches also provide winter color and texture.

Like all hydrangeas, the shrubs are toxic to humans, dogs, cats, and horses.

Oakleaf Hydrangea Care

Plant new oakleaf hydrangea either in the late fall or early spring when the plant is dormant and it won't be stressed by higher temperatures. This shrub will do best when planted in a slightly acidic, rich, well-draining soil in full sun or part shade. It thrives in moist soil; a thick layer of mulch over the root zone will help retain soil moisture.

Light

In their native habitat, oakleaf hydrangeas are understory plants, so they appreciate afternoon shade, especially in southern climates where nearly full shade may be necessary. In the North, oakleaf hydrangeas can get by with full sun. Too much shade may reduce the intensity of the fall color.

Soil

Grow oakleaf hydrangea in well-drained soil with a slightly acidic soil pH (5.0-6.5), amended with plenty of compost.

Water

These plants appreciate moist soil, and the more sunlight they receive, the more water they need. Blanketing the ground beneath the shrub with a thick layer of mulch will help maintain soil moisture.

Temperature and Humidity

Oakleaf hydrangea generally does well in climate conditions throughout its hardiness range (zones 5 to 9), but winter damage to flower buds may occur in the colder part of the range, especially with young shrubs.

Fertilizer

This plant generally requires no feeding, especially if you are mulching over the root zone. When growing in alkaline soils, occasional feeding with an acid fertilizer may be beneficial.

Oakleaf Hydrangea Varieties

• 'Snow Queen': One of the most popular cultivars of oakleaf hydrangea is 'Snow Queen', which produces panicles of white flowers in early summer that gradually fade to pinkish-brown by fall. The floral display is very long-lasting.
• 'Snowflake': This cultivar is preferred by some growers since it has double flowers.
• 'Ruby Slippers': This cultivar may be more suitable for those who garden in small spaces, as it stays more compact at 3 to 4 feet tall and wide. The flowers of 'Ruby Slippers' age to a reddish color, true to its cultivar name.

Pruning

Oakleaf hydrangea shrubs usually require little pruning, unless you are trying to fit them into a location that is too small. In ideal conditions, this plant may shoot up to 10 feet, which may require that you trim it down. This is a shrub that blooms on old wood, so when pruning is necessary, do it immediately after it is done flowering and blooms start to fade, which will likely be late summer into September or even October. Damaged or diseased branches can be cut away whenever they appear.

This plant spreads through suckering, so you may want to remove spreading ground shoots to control the spread of the shrub.

Propagating Oakleaf Hydrangea

Oakleaf hydrangea shrubs can be successfully propagated through stem cuttings. Follow these propagating steps:

1. With clean, sharp pruners, snip two to four cuttings from green stem tips that have no flowers. Make sure the cuttings have at least one growth node (a knobby line across the stem).
2. Remove the leaves from the lower half of the cutting.
3. Dip the end of the cutting into rooting hormone.
4. Plant the cuttings in moist, sterile potting mix.
5. Place the planted cuttings in a plastic bag and keep them out of direct sunlight.
6. Make sure the soil remains moist but not soggy.
7. Within about 12 weeks, root growth should be sufficient to transplant the plant into the garden or a larger pot for continued growth.

How to Grow Oakleaf Hydrangea From Seed

Propagating a popular cultivar such as 'Snow Queen' from seed does not produce a plant true to type. Therefor it is recommended to propagate it from stem cuttings as described above.

Overwintering

At the northern end of its hardiness range (zone 5), young plants should be given some winter protection, such as a burlap wrap.

Common Pests & Diseases

Oakleaf hydrangea suffers from no serious pest or disease issues, but non-threatening powdery mildew or leaf blight may occur. Aphids and spiders can also sometimes appear.

How to Get Oakleaf Hydrangea to Bloom

Failure to bloom can have several reasons. The shrub might not get sufficient sunlight. While hydrangeas prefer dappled shade, they do need sun to bloom. Lack of water might be another reason. Keep the soil moist and add a generous layer of mulch to prevent the soil from drying out.

It could also be that you used a fertilizer with a high amount of nitrogen, with the result of lush foliage but no flowers. Switch to a bloom-boosting fertilizer that is high in phosphorus (P).

Another possibility is that you accidentally removed the flower buds when pruning (oakleaf hydrangeas bloom on old wood), or the flower buds were killed by a late freeze in the Spring.

If you tried all of those options and your hydrangea still does not bloom, it might be simply too young. Continue to give it the proper care and keep your fingers crossed that you will see it bloom next year.