How to Grow and Care for Oakleaf Hydrangeas, the Color-Changing Shrub Your Garden Is Missing

While there are many hydrangea types well-suited to 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 how 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.

How to Plant Oakleaf Hydrangeas

Oakleaf hydrangeas can be planted from their container straight into the ground during spring, early summer, or early fall. "Do not plant shrubs in any harsh weather conditions like July and August or January and February," says Ryan Zawojski, owner and lead designer of RYZ Designs.

Start by choosing where you want to plant them. "Pick a spot that will accommodate your hydrangea at its mature size," says Ryan Mcenaney, public relations and communications specialist for Bailey Nurseries and author of Field Guide to Outside Style. “The mature size of oakleaf hydrangeas varies. 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.”

1. Dig a hole slightly larger than the pot your hydrangea came in. It should be deep enough so that where the plant meets the soil is flush to the ground. 
2. Place your plant in the middle of the hole. 
3. Back fill in the sides with soil. 
4. Water thoroughly at the base of the plant, let the water soak in, and water again.

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 for these hydrangeas,” 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. 

Soil

The deciduous shrub performs best when planted in 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

Applying a granular fertilizer will only be necessary if you notice the leaves drooping or not blooming altogether. "A fresh layer of cedar mulch is all you need sometimes because it is filled with nitrogen phosphorus potassium that keeps the pH level in check,” says Zawojski.

How to Prune Oakleaf Hydrangeas

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 flower fades,” 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 landscape, 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 drainage holes 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 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. “This can be done with mulch or pine straw,” says Mcenaney. “As the plant gets larger in size, you could use a light frost cloth to protect the flower buds.” Once the shrub becomes well established, it won’t require as much winter protection. 

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: 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: 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: 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 four-legged friends from nibbling on 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 a deer repellent spray. Otherwise, the critters are likely to make short work of your shrubs, Zawojski says.

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.