How to Grow and Care for Oakleaf Hydrangea

Oakleaf hydrangea is a flowering deciduous shrub with long-lasting flower panicles that emerge white but gradually transition to purplish pink on sturdy stems. Its distinctive leaves have lobes like those of an oak tree ("quercifolia" means "oakleaf" in Latin). It grows from 4 to 8 feet tall.

Oakleaf hydrangea grows slower than other hydrangeas, about 1 to 2 feet per year. It prefers slightly acidic, rich, well-draining soil in full sun or partial shade. It thrives in moist soil; a thick layer of mulch over the root zone will help retain soil moisture. Like all hydrangeas, the shrubs are toxic to humans and pets.

How to Plant Oakleaf Hydrangea

When to Plant

Plant oakleaf hydrangea in the fall after the high heat diminishes or in the early spring after the frost period has passed.

Spacing, Depth, and Support

When transplanting a plant from the nursery, give the plants space by planting them 4 to 8 feet apart. Dig a hole slightly deeper than the root ball and make the hole two to three times wider than the root ball.

Loosen the soil from the root ball and set the plant in the hole with the top of the root ball slightly above the surface level. Backfill the hole, tamp it down, and water the plant. Place a thick layer (2 to 3 inches deep) of mulch on top.

Some other types of hydrangea require staking (such as Incrediballs), but oakleaf hydrangeas usually do not need support. Giant flower heads can sometimes cause the plant to flop, so consider using stakes if it needs support.

Oakleaf Hydrangea Care

Oakleaf hydrangeas are deciduous or perennial plants, returning year after year. Here are the main care requirements for growing an oakleaf hydrangea:

• Plant in the late fall or early spring when it's dormant.
• Prefers soil that is slightly acidic, moist, rich, and well-draining.
• Likes full or partial sun.
• Provide a thick layer of mulch over the root zone to help retain soil moisture.
• Protect young flower buds with a winter wrap in the lower range of its USDA zones 5 and 6.
  
• Give an acidifying fertilizer if the soil is alkaline.
  

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 pH (5.0-6.5), amended with plenty of compost.

Water

These plants appreciate moist soil; 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). Still, 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.

Types of Oakleaf Hydrangea

Oakleaf hydrangeas come in many varieties, including single- or double-flowering types and compact and tall types. This hydrangea has a rounded, upright growth habit, making it a good specimen plant. It also works well as a foundation plant or when massed in shrub borders or open woodland gardens.

Oakleaf hydrangea is beneficial in that it attracts pollinators, like butterflies and bees, and the seeds provide food for songbirds.

Its fall foliage color is attractive—the leathery leaves turn purple, orange-bronze, or red. The peeling and exfoliating branches also provide winter color and texture. Its flowers are single or double-flowering varieties, ranging from white, pink, blue, purple, beige, and green. Here are the popular types of oakleaf hydrangea:

• '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 'Ruby Slippers' flowers age to a reddish color, true to its cultivar name.
• 'Gatsby Pink': Green leaves that turn dark red in autumn; starts with huge white flowers that turn pink later in summer
• 'Gatsby Moon': Grows 6 to 8 feet tall and 8 feet wide, features double flowers that start white and turn green.
• 'Alice': Can grow 8 to 12 feet tall. Its leaves start green and turn bronze-red, and its 12-inch flowers turn white to pink.

Warning

Unlike other hydrangeas, especially cultivars bred for container planting, oakleaf hydrangeas do not like the restricted space of a container or pot and may not thrive. Growing this plant in pots is not recommended.

Pruning

Damaged or diseased branches can be cut away whenever they appear. Oakleaf hydrangea shrubstend to spread out and often do so unevenly, branching in all directions. Annual pruning or trimming back unruly branching every two years will keep your hydrangea shapely and healthy.

This plant may shoot up to 10 feet in ideal conditions, requiring trimming. Since it blooms on old wood, wait to prune until after flowering, when blooms start to fade, usually in late summer. The best rule of thumb is not to prune past July. It may start setting buds in early fall for the next growing season.

Propagating Oakleaf Hydrangea

This multi-stemmed shrub spreads by suckering, so you may want to remove spreading ground shoots to control the shrub's spread. 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 with no flowers. Ensure 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 the rooting hormone.
4. Plant the cuttings in a 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. It is best to propagate oakleaf hydrangeas from stem cuttings.

Overwintering

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

Common Pests & Plant Diseases

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

How to Get Oakleaf Hydrangea to Bloom

Bloom Months

Oakleaf hydrangea typically blooms in late spring or early summer. If growing conditions remain consistent, they should rebloom each year. Deadhead old blooms as soon as they fade by the end of July. After that, stop pruning or deadheading.

What Do Oakleaf Hydrangeas Look Like?

Oakleaf hydrangeas have cone-shaped clusters of small, creamy white flowers with rounded or pointed petals in single or double flowers. The petals start white and turn pink, red, green, or beige. Oakleaf hydrangeas have a pleasant, mild floral scent.

How to Encourage More Blooms

If a hydrangea fails to bloom, it may be too young. Other reasons for failure to bloom or low flower production could be insufficient sun or water, too much nitrogen-rich fertilizer, or incorrect pruning.

• Hydrangeas prefer dappled shade, but insufficient light can affect the plant's ability to bloom.
• Keep the soil moist and add a generous layer of mulch to prevent the soil from drying out.
• Avoid fertilizers high in nitrogen, which promote more leaf growth over flower production. Instead, get phosphorus-rich bloom-boosting fertilizer.
• Do not prune after July; you might inadvertently remove new bud growth.
  
• Protect buds with a winter wrap since a late freeze in the spring can hurt them.
  

• Do oak leaf hydrangeas get big?

  Oakleaf hydrangeas can grow to an average height of 8 feet, with smaller compact varieties ('Ruby Slippers') growing between 3 and 4 feet tall. Depending on the type and growing conditions, oakleaf varieties can get smaller (young or dwarf) or taller (up to 12 feet).

• How do I know if my hydrangea is oakleaf?

  The oakleaf hydrangea leaves are deeply lobed and look like the leaves of an oak tree.

• Do oakleaf hydrangeas bloom more than once?

  They only bloom once, unlike hydrangea cultivars of other species, such as Endless Summer hydrangea, which bloom repeatedly. However, the blooms are long-lasting and change from white to red, pink, and purple shades, and finally brown.

• How long does an oakleaf hydrangea live?

  These long-lived shrubs can live up to 50 years when given proper care.

• Why are my oakleaf hydrangea's leaves turning yellow?

  Your oakleaf hydrangea may have yellow leaves because it was overwatered. Wilted yellow leaves also suggest overwatering. Or, the leaves are older and naturally yellowing, reacting to an iron deficiency, or there is a pest infestation. Test the soil pH, check the watering, and look for signs of pests.

From: thespruce