How and when to prune an oakleaf hydrangea – pick the right moment or risk missing out on a year of flowers

Oakleaf hydrangeas are large-growing shrubs that do not need a lot of extensive pruning to guarantee a beautiful display of creamy white blooms in summer. However, for when the shrub does need a bit of a trim, it is important to know the right time to prune.

When it comes to hydrangea pruning, getting the timing right is imperative and a failure to get it right can mean a full year without any flowers. If you are growing hydrangeas as part of your backyard ideas, then knowing the type you have is important as you do not want to treat them all the same. 

If you have any of these fantastic shade-loving shrubs in your backyard, then we look in-depth at when to prune an oakleaf hydrangea and get some expert tips to help you trim correctly and keep your shrubs happy.

Do you need to prune oak leaf hydrangeas? 

Oakleaf hydrangeas are very low maintenance hydrangeas, but they do benefit from a bit of regular pruning to keep healthy and producing blooms. The amount of trimming is minimal and it helps to prevent the hydrangea becoming overgrown and unruly.

When is the best time to prune oak leaf hydrangeas

Many types of hydrangea are pruned in fall or late winter - for example that is the time to prune Annabelle hydrangeas and prune limelight hydrangeas among others - however that would be a pruning mistake for oakleaf hydrangeas. 

When pruning hydrangeas, the timing and method all depends on the type of hydrangea and whether it blooms on new or old wood. It is vital to know the type of hydrangea you are cutting to avoid missing out on a year’s worth of flowers.

Lorraine Ballato, hydrangea expert and author of Success with Hydrangeas, explains how oakleaf hydrangeas flower on old wood - the growth from the previous season. The general rule of thumb is to prune these plants after they have finished blooming in mid-to-late summer.

However, the earlier you can prune oakleaf hydrangeas in the year can be highly beneficial. It gives the shrubs the most time possible to produce growth and buds that will carry flowers the following year. 

‘The best time to prune is just after flowers and buds appear,’ says Lorraine. ‘Pruning too much later risks removing the following year’s flowers.’

If you are not bold enough to head out early as the first flowers are appearing, then waiting until after the hydrangea has flowered will give the shrub the time it needs to put on growth that will flower next year. 

Restrict the pruning for shape and size - and to deadhead hydrangeas -  to the summer months only, as heading out with the pruning shears at any other time of year will not reward you. 

Nastya Vasylchyshyna, resident botany expert at Plantum, warns: ‘Pruning it thoroughly in late winter or spring will result in removing the shoots that would form the current season's flower buds, so you'll have to wait a year for the shrub to replace them.’

The one reason you may prune oakleaf hydrangeas outside of summer is to remove any dead, diseased, or damaged branches you may spot during the year. As trimming these out is vital to the future health of the plant, it is fine to cut these out at any time of year. 

Any faded flowerheads that have been killed by winter frosts can also be cut off in spring after the risk of frost has passed in your US hardiness zone.

Lorraine Ballato

Lorraine Ballato is a hydrangea expert and the the author of the international best selling book 'Success with Hydrangeas', available at Amazon. She is also an in-demand speaker throughout the US and the resident hydrangea expert at the New York Botanical Garden

Nastya Vasylchyshyna

Nastya Vasylchyshyna is a professional botany expert for the Plantum app that helps identify plants and plant diseases and provides care recommendations. 

How to prune oakleaf hydrangeas

The good news is that oakleaf hydrangeas rarely need lots of pruning. It does not require intricate annual trimming and is often picked by homeowners for its size and low maintenance. 

Lorraine Ballato hails the oakleaf hydrangea as being a fantastic option as ‘an understory plant’ or a plant ‘at the edge of the garden’ - as well as being the ‘least demanding of the hydrangea options’.

She warns against trying to prune regularly in an attempt to contain the shrub at a smaller size, saying: ‘This plant can get quite big so gardener's have the urge to cut it back to restrict its growth. That won’t work too well as the plant always reverts to its genetic predisposition.’

When it comes to how to prune, it is a case of removing the three D’s (dead, diseased, or damaged wood) and any branches that are going in wayward directions, to create the desired shape.

Lorraine recommends it is often ‘best to remove branches at the base if needed’, though you can prune back to above a pair of buds to gently shape the shrub. Regularly step back to make decisions on what stems to prune and assess the overall shape of the shrub.

Always use clean and sharp garden tools, such as a pair of pruning shears and loppers, to prune hydrangeas - and sanitise tools before and after use to avoid spreading diseases from plant-to-plant around the backyard. 

Also, show caution and follow the one-third pruning rule, to never cut out more than a third of the growth at any time. Any large-scale rejuvenation of the shrub should be done over a series of years.

FAQs

Can you prune oakleaf hydrangeas in spring?

You should not prune oakleaf hydrangeas in late winter or spring as you do other hydrangeas. Only prune hydrangeas that bloom on new wood during that time of year. Pruning oakleaf hydrangeas in spring will only mean removing any shoots that would be carrying the current season’s flower buds. It will mean the hydrangea won’t bloom that year and you’ll need to wait another year for the shrub to replace those buds.

Hydrangeas are hugely-popular shade-loving plants and, thanks to newer compact types of hydrangea, it means that even people looking for small backyard ideas can grow hydrangeas in pots and get a fantastic display of summer blooms.