Pruning oakleaf hydrangeas (When & How To Do It Right)

Pruning oakleaf hydrangeas (Hydrangea quercifolia) in your backyard is important in maintaining the health and beauty of this landscape plant. 

With their striking foliage and showy blooms, oakleaf hydrangeas (also called Bigleaf, or French hydrangea) require regular maintenance, including proper pruning techniques. 

However, improper pruning can damage the plant and reduce its blooming potential. In this blog post, we will discuss when and how to prune oakleaf hydrangeas to keep them looking their best.

You’ll surely find useful tips to help you prune your oakleaf hydrangeas like a pro. Let’s get started!

Read the Full Guide: Hydrangea Tree Care. Varieties & Planting Guide.

Oakleaf Hydrangea Overview

When to prune oakleaf hydrangea

In the UK as well as in any other place, the best time for pruning oakleaf hydrangeas is in the Summer, after the plant is done flowering and blooming.

This is also general for United State Hardiness Zones between 5 to 9 including Georgia, Texas and even Canada.

This is because oakleaf hydrangeas bloom on old wood, which means the flower buds form on the previous year’s growth. Pruning in late summer or early autumn gives the plant enough time to develop new growth and set flower buds for the following year. 

Pruning too late in the season can result in cutting off the buds and reducing the plant’s blooming potential for the next season. 

Avoid pruning oakleaf hydrangeas in the spring as it can remove the flower buds that have already formed, resulting in little to no blooms for the current year.

Tools needed for pruning oakleaf hydrangeas

To properly prune an oakleaf hydrangea, you will need a few essential tools. These include:

1. Pruning Shears: Also known as secateurs, pruning shears are used to trim small branches, twigs, and stems. Choose a high-quality pair with sharp blades that can cut cleanly through the plant material.
2. Loppers: For thicker branches, you will need a pair of loppers. These have longer handles and larger blades that can cut through branches up to 2 inches in diameter.
3. Pruning Saw: If you need to remove larger branches, a pruning saw is essential. Choose a saw with a curved blade that can fit into tight spaces and make clean cuts.
4. Gloves: To protect your hands from thorns, scratches, and other hazards, wear a pair of sturdy gardening gloves.
5. Eye Protection: When using saws and loppers, wear eye protection such as safety glasses or goggles to prevent debris from getting into your eyes.

Step-by-step guide and Tips on pruning oakleaf hydrangeas

If you want to keep your oakleaf hydrangeas healthy and looking their best, pruning is an essential task. 

Here is a step-by-step guide on how to prune an oakleaf hydrangea:

• Cut back old wood
• Remove dead or damaged wood
• Remove old wood
• Prune for shape and size
• Cut back long stems
• Remove weak or crossing branches
• Clean up
• Mulch

Before you start pruning, assess the plant’s health. Look for any dead, damaged, or diseased wood, as well as any crossing or rubbing branches that could cause damage.

Cut back old wood:

Oakleaf hydrangeas bloom on old wood, which means the flower buds form on the previous year’s growth. To encourage new growth and more blooms, Cut the oldest stems all the way down to the ground, making the cut just above a healthy bud. Just be careful not to remove too much old wood,  as this can reduce the blooming potential for the following year.

Remove dead or damaged wood:

Use sharp pruning shears to cut back any dead or damaged wood. This deadheading, or removing spent blooms will keep the plant healthy and prevent disease from spreading.

Remove old wood:

Oakleaf hydrangeas produce flowers on old wood, which is wood that is at least two years old. To encourage new growth and more blooms, remove up to one-third of the oldest wood each year.

Prune for shape and size:

Once you’ve removed any damaged wood, take a step back and assess the plant’s overall shape and size. Prune back any branches that are crossing, rubbing, or growing in an undesirable direction. Aim to maintain a natural shape for the plant, rather than trying to force it into a specific shape.

Cut back long stems:

If any stems are too long or out of shape, prune them back to a healthy bud or branch. This will help keep the plant compact and encourage more branching.

Remove weak or crossing branches:

If you notice any branches that are weak, crossing over each other, or rubbing against each other, remove them. This will improve the plant’s structure and prevent damage.

Clean up:

After pruning, clean up any debris around the plant and dispose of it properly.

Mulch:

Finally, add a layer of mulch around the base of the plant to help retain moisture and suppress weeds.

Frequently Asked Questions on Pruning oakleaf hydrangeas.

Should you cut back oakleaf hydrangea?

Yes, oakleaf hydrangeas can be pruned to remove dead, damaged, or overgrown branches. Pruning can also help promote new growth and encourage more blooms.

How far to cut back oakleaf hydrangea?

When cutting back oakleaf hydrangea, you can remove up to one-third of the oldest wood each year to promote new growth and more blooms. Cut the oldest stems all the way down to the ground, making the cut just above a healthy bud.

How far back can you prune oakleaf hydrangea?

You can prune oakleaf hydrangea back up to one-third of its total size each year, but avoid pruning more than that as it can reduce the number of blooms in the following season.

Taking cuttings from oakleaf hydrangeas

• Choose a healthy stem of about 6 inches long with at least two sets of leaves.
• Remove the bottom leaves leaving a bare stem at the bottom.
• Dip the stem in the rooting hormone to develop roots.
• Plant the cutting in a container with a well-draining potting mix.
• Water the cutting.
• Place a clear plastic bag over the cutting and container to create a mini greenhouse. This will help keep the soil moist and create a humid environment that is ideal for rooting.
• Place the cutting in a warm, bright location.
• Monitor the cutting: Check the cutting regularly to ensure that the soil is moist and that the plastic bag is not creating too much condensation. After about 4-6 weeks, the cutting should have rooted and be ready to transplant to a larger pot or outside in the garden.

Oakleaf Hydrangea Maintenance 

Watering requirements

Oakleaf hydrangeas require consistent watering during their growing season, which is from spring to fall.

Hydrangea plants prefer moist, well-draining soil, so it’s important to water them deeply but not too frequently. Aim to water them once a week, or more often if the weather is particularly hot and dry.

Fertilizing 

When it comes to fertilizing, oakleaf hydrangeas do not require a lot of fertilizer. You can fertilize them once in the spring with a slow-release, balanced fertilizer, such as a 10-10-10 or 12-12-12 blend.

Avoid using high-nitrogen fertilizers, as this can encourage excessive leaf growth at the expense of flower production.

Soil conditions and pH level

Oakleaf hydrangeas prefer slightly acidic soil with a pH between 5.5 and 6.5. If your soil is too alkaline, you can lower the pH by adding sulfur or aluminium sulfate. You can also amend the soil with organic matter, such as compost or peat moss, to improve its texture and drainage.

Is your oakleaf hydrangea too big? How to control its growth

If your oakleaf hydrangea is too large for its space, you can prune it back during Summer. Remove up to one-third of the oldest and thickest branches, cutting them back to the base of the shrub. This will encourage new growth and help control the size of the plant.

Pruning oakleaf hydrangea in winter – oakleaf hydrangea winter care

During winter, Pruning oakleaf hydrangeas is best done late, before new growth begins. Remove any dead, damaged, or diseased branches, as well as any crossing or rubbing branches. 

Pruning oak leaf hydrangeas in fall

It’s generally not recommended to prune oakleaf hydrangeas in the fall, as this can stimulate new growth that may not have time to harden off before winter. 

However, if you need to remove any dead or diseased wood, it’s best to do so in the fall.

Pruning oakleaf hydrangea in spring

Spring is a good time to prune oakleaf hydrangeas, as it allows you to remove any winter damage and shape the plant before it starts to grow for the season.

Oak leaf hydrangeas Pest and Disease – Treatments

Oakleaf hydrangeas can be susceptible to a few pests and diseases. Here are some common ones and their treatments:

Powdery Mildew.

A fungal disease that causes a white, powdery coating on the leaves and stems of oakleaf hydrangeas. To treat, remove any infected leaves or branches and dispose of them. You can also spray the plant with a fungicide labelled for powdery mildew.

Leaf Spot.

 This fungal disease can cause dark spots on the leaves of oakleaf hydrangeas. To treat, remove any infected leaves or branches and dispose of them.

You can also spray the plant with a fungicide labelled for leaf spot.

Aphids.

 Small, soft-bodied insects. They feed on the leaves and stems of oakleaf hydrangeas, causing distorted growth and yellowing leaves.

Spray the plant with insecticidal soap or neem oil.

Scale.

 These small, hard-shelled insects can feed on the stems and branches of oakleaf hydrangeas, causing yellowing leaves and stunted growth.

To treat, remove any infected branches and dispose of them. You can also spray the plant with horticultural oil.

Japanese Beetles.

 These beetles can feed on the leaves and flowers of oakleaf hydrangeas, causing skeletonized leaves and damaged blooms.

To treat, handpick the beetles and drop them into a bucket of soapy water. You can also spray the plant with an insecticide labelled for Japanese beetles.

Oakleaf  Hydrangea varieties

There are several different varieties of oakleaf hydrangeas available, each with their unique characteristics. 

Here are a few popular ones:

1. Alice Hydrangea – This variety has large, white flower clusters that fade to pink in the fall. It also has attractive burgundy fall foliage.
2. Snow Queen Oakleaf Hydrangea – This variety has large, white flower clusters and glossy, dark green foliage that turns burgundy in the fall.
3. Pee Wee Oakleaf Hydrangeas– This compact variety has smaller white flower clusters and is well-suited for smaller gardens or containers.
4. Sikes Dwarf Hydrangea– This very compact variety has smaller white flower clusters and grows to only about 2-3 feet tall.
5. Ruby Slippers Oakleaf Hydrangea – This newer variety has large, cone-shaped flower clusters that start out white and gradually turn pink, then deep red in the fall.
6. Munchkin Oak leaf Hydrangea – This dwarf variety has small, white flower clusters and grows to only about 2-3 feet tall and wide.
7. Little Honey Oakleaf Hydrangea – This unique variety has chartreuse foliage that turns pink in the fall, and white flower clusters. It grows to about 3-4 feet tall and wide.
8. Sykes – This compact variety has large, white flower clusters and grows to only about 3-4 feet tall and wide.

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