How to Grow and Care for Oakleaf Hydrangeas, a Low-Maintenance Variety That Changes Color

While there are many types of hydrangeas that will look beautiful in your garden, the oakleaf variety provides added interest thanks to its large, lobed foliage that resembles an oak tree's leaves. The foliage transitions from green to maroon throughout the season, falling off in winter to reveal beautiful exfoliating bark. Beyond its impressive foliage, the plant's blooms also put on quite the show, changing from white to a stunning pink or red as the plant matures. Hardy in USDA growing zones 5 to 9, oakleaf hydrangeas are an easy-to-grow shrub that return year after year when cared for properly.

When and Where to Plant Oakleaf Hydrangeas

Oakleaf hydrangeas can be planted from their container straight into the ground in an area that receives partial shade and has well-draining soil. Plant during late fall or early spring, as oakleaf hydrangeas won't establish well in harsh weather conditions, like during peak summer or winter.

Plant oakleaf hydrangea in an area that can accommodate its full size. “The mature size of oakleaf hydrangeas varies," says Ryan Mcenaney, public relations and communications specialist for Bailey Nurseries and author of Field Guide to Outside Style. "More dense, compact varieties like Jetstream grow to around 5 feet tall and wide, while others like Alice can get up to 8 feet tall and wide.”

How to Plant Oakleaf Hydrangeas

When planting oakleaf hydrangeas, find an area in your yard that satisfies its sun and soil requirements. "Oakleaf hydrangeas prefer moist, fertile soil but can tolerate a range of soil types," says Kelly Funk, president of Jackson & Perkins.

1. Dig a hole twice as wide and as deep as the root ball of the hydrangea plant.
2. Prepare the soil by mixing organic matter, such as compost, with the soil you removed from the hole. 
3. Gently remove the hydrangea from its container and place it in the center of the hole. Ensure the top of the root ball is level with the surrounding soil.
4. Fill the hole with the soil mixture, gently tamping it down as you go to remove air pockets.
5. Water the plant thoroughly after planting to help settle the soil around the roots.
6. Apply a layer of mulch around the base of the plant to help retain moisture and suppress weeds.
7. Keep the soil consistently moist, especially during the first growing season.

How to Care for Oakleaf Hydrangeas

Despite being relatively easy to maintain, oakleaf hydrangeas have some care requirements you need to meet in order to encourage healthy blooms. 

Sunlight

Oakleaf hydrangeas prefer partial shade. “Oakleaf hydrangeas are discovered in nature in wooded areas and along the banks of streams, so dappled shade is great,” says Mcenaney. “They can handle some full sun, but especially in warmer climates, having part shade is ideal.” 

Water

Make sure to water your newly planted hydrangea often to help it get established. Use a gardening hose to water the base of the plant, making sure to avoid the foliage. Keep the soil evenly moist but not soggy.  Water deeply and avoid letting the soil dry out completely, says Funk.

Soil

Oakleaf hydrangeas perform best when planted in fertile, loamy soil, which means it has an even mixture of sand, silt, and clay. Oakleaf hydrangeas also like their soil to be well-draining.

Fertilizer

Oakleaf hydrangeas don't typically need a fertilizer to thrive, but you can apply a granular fertilizer in early spring or if you notice the leaves are drooping or not blooming.

How to Prune Oakleaf Hydrangeas

Prune oakleaf hydrangeas right after their flowering season. Oakleaf hydrangeas bloom on the previous season’s growth, so you don’t want to prune in fall or later winter like you do with some other hydrangea types. “If you’re going to prune for shape, size, or to deadhead spent blooms, do so in summer after the flowers fade,” says Mcenaney. “You want to avoid pruning too late in the season, or you may remove the flower buds for next year.” When pruning for aesthetics, use sharp, clean scissors to cut the shrub to your liking or snip off dead or dying blooms. 

How to Repot Oakleaf Hydrangeas

Although they’re commonly grown in the ground, oakleaf hydrangeas also work as a container plant. Once it gets too big for its container, repot it following the steps below.

1. Choose a pot with a drainage hole that is slightly larger than the current container. 
2. Fill the container with potting mix and place your hydrangea in the center, making sure the soil line is a couple of inches below the top of the container. 
3. Loosen the roots at the bottom and place the plant in the container. 
4. Fill in the sides of the container with potting soil. 
5. Water thoroughly at the base of the plant.

Winterization

While some hydrangea varieties don’t require much winter care, oakleaf hydrangeas need to be protected since they bloom on the previous season’s growth. "Apply a layer of mulch around the base of the plant in late fall to help insulate the roots and retain soil moisture," says Funk. "Use a thick layer of organic mulch, such as shredded bark or compost, but avoid piling it up against the stems, as this can promote rot."

Keep the soil around the hydrangea moist throughout fall to ensure the plant is hydrated going into winter. Funk also recommends avoiding heavy pruning in fall, which can stimulate new growth that may be vulnerable to frost damage. If you're expecting a particularly cold or snowy winter, protect the shrub with burlap or install a protective cover.

How to Get Oakleaf Hydrangeas to Bloom

To encourage your oakleaf hydrangeas to bloom, ensure they receive sufficient sunlight and prune them at the right time. "Avoid pruning too late in the season, as it can remove flower buds," agrees Funk. "Water regularly and fertilize in early spring with a balanced fertilizer for flowering shrubs." If your oakleaf hydrangeas don't bloom, consider factors such as insufficient sunlight, extreme temperatures, or improper pruning.

Types of Oakleaf Hydrangeas

There are several varieties in the oakleaf family, but these are the most common. 

Jetstream Hydrangea

A compact oakleaf hydrangea with a non-flopping habit, Jetstream has gorgeous dark green foliage that’s resistant to leaf spot and turns orange-red in fall. “Flowers bloom in early summer and are a beautiful white that ages to pink,” says Mcenaney. “Jetstream is great for mass planting, especially in a woodland setting.”

• Zones: 5 to 9
• Size: 5 feet tall x 5 feet wide 
• Care requirements: Part sun; moist, well-draining soil 

Alice Hydrangea

Best grown as a very large garden or massing shrub, Alice has enormous showy flower spikes that fade from white to pink as they mature. “It has beautiful lobed foliage with reliable fall color and papery bark,” says Mcenaney. “It can be rather coarse in appearance [and is] best used in groupings in a woodland-type setting.”

• Zones: 5 to 9
• Size: 8 feet tall x 8 feet wide 
• Care requirements: Part sun; moist, well-draining soil 

Ruby Slippers Hydrangea

With an abundance of exceptionally large white blooms in summer that age to deep pink, the Ruby Slippers variety has robust blooms that stay upright even after heavy rains. “Dark green, deeply lobed oak-like foliage turns brilliant mahogany in fall,” says Mcenaney. “The compact form works in smaller landscapes and is useful for mass planting, hedges, or borders.”

• Zones: 5 to 9
• Size: 3 to 4 feet tall x 3 to 5 feet wide 
• Care requirements: Part sun; moist, well-draining soil
  

Common Problems

Although they're a hardy hydrangea variety, there are a few pests and diseases you may encounter when caring for oakleaf hydrangeas.

Deer

Oakleaf hydrangeas attract deer. To keep deer away from your plant, consider planting your oakleaf hydrangeas in a fenced-in area, in a pot on your patio, or in an area that has been treated with an organic deer-repellent spray.

Powdery Mildew

If you spot a whitish-gray substance on your plants, it may be powdery mildew. "Powdery mildew can occur on oakleaf hydrangeas when there is water or humidity present and a lack of airflow," says Mcenaney. "Spores collect on wet leaves and can give the plant an appearance of powder covering the foliage." Prevent this by watering the base of your plant, not the foliage. To treat powdery mildew, you can apply a fungicide or remove leaves once they’ve fallen.

Cercospora Leaf Spot

This plant disease presents as angular, dark brown spots on leaves. "As the foliage becomes more infected, it can fall off and release additional fungal spores, spreading Cercospora to more leaves or other plants," says Mcenaney. "Similar to powdery mildew, watering at the base and removing infected leaves can prevent the spread of the leaf spot disease."

Botrytis Blight

A fungal disease that occurs in cool, wet environments, Botrytis can infect leaves and flower buds before they open, which will kill the flower and prevent it from blooming. The disease initially looks like water spots on the leaves and then turns to red-brown infections. Watering in the morning at the base of the shrub and improving circulation can help prevent Botrytis. Applying a copper fungicide can also help keep it at bay. "If you have blight on your oakleaf hydrangea, remove the affected foliage and clean your pruners between each cut to prevent a spread," says Mcenaney.