How to Deadhead Hydrangeas

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Everyone loves the hydrangea and thinks of the giant mophead or the more delicate but equally spectacular lacecap varieties. Gorgeous, long-lasting blooms that seem to go on and on throughout the summer. But when the blooms have faded, uncertainty abounds as to what is the correct approach to take.

Which Types of Hydrangea Can You Cut Off Dead Blooms?

For the purposes of deadheading, it is important to know that there are five distinct types of hydrangea bushes that are commonly grown in gardens around the world. Before you deadhead your hydrangeas, you should identify which variety you have, as the procedure to follow will depend on this. 

Bigleaf Hydrangeas

Bigleaf hydrangeas (Hydrangea macrophylla) is the most widely grown of hydrangea shrubs.  Both the mophead and lacecap varieties come into this group. Bigleaf hydrangeas are those plants that give magnificent floral displays every summer, with huge clusters of usually pink or blue flowers.

Climbing Hydrangeas

Climbing hydrangea is a beautiful, perennial vine which once established will grow rapidly and reach 30 feet (9.14 meters) tall. It bears large white flowers and is a great choice if you want to hide an ugly building or wall.

Hydrangea Arborescens

Also known as smooth or wild hydrangeas, these shrubs are ideal if you want to plant a hedge and have masses of white flowers. They tolerate heat better than most other hydrangea varieties, too.

Oakleaf Hydrangea

Named because its leaves resemble the leaves on an oak tree, the oakleaf hydrangea bush offers both floral and foliage interest. Sometimes the leaves can be enormous, up to 10 inches (25.4 centimeters) long and broad. The leaves change color from vibrant green in summer, to orange, then red, and finally to brown as the fall advances.  

Panicle Hydrangea

The panicle hydrangea has large, conical flowers which start pink and change to shades of pinkish-red. They are considered to be the easiest and most reliable of all hydrangeas to grow.

What is Deadheading?

Deadheading simply refers to the process of removing spent flower heads from the plant. It is commonly and incorrectly thought of as pruning, but deadheading is just removing flowers, nothing else. 

Should I Deadhead Hydrangeas?

You aren’t hurting the plant at all by removing dead flowers. Once they are removed, the plant will stop trying to produce seeds and instead focus its energies on forming new growth and root development.

Deadheading also improves the look of your hydrangea, which can look uncared for and scruffy if flowers that have finished and turned brown remain on the shrub.  

Deadheading hydrangeas isn’t essential, but providing it is done correctly at the right time of year will benefit both your plant and the look of your garden. No-one wants to look at dead or dying flowers!

When to Deadhead Hydrangea Shrubs

The importance of knowing which type of hydrangea you have can’t be over-emphasized when it comes to removing faded hydrangea flowers. It’s all to do with knowing whether your hydrangea bush flowers on old wood or new wood, and understanding what this means.

Deadheading Hydrangeas that Flower on Old Wood

Bigleaf hydrangeas (both mophead and lacecap varieties), climbing and oakleaf hydrangeas all flower on old wood.

Because these shrubs flower on old wood, they start to produce the following year’s flower buds on existing woody stems during the summer, even when the present year’s flowers are still in bloom. This is why you have to be very careful when removing the faded flowers from these varieties of hydrangeas.

The best time to remove the flowers from these varieties is as soon as possible once the blossom has finished. Ideally, this will be before August. Usually, the flowers will be over by July and if you cut short stems only, or as close to the bloom as possible, you will not risk damaging next year’s developing flower buds. 

Some people advocate not removing the faded blossoms from this type of hydrangea at all and just leaving the plant alone. This avoids the risk of damaging the buds. Another reason to consider leaving the dead flowers in situ, is that the faded blooms can protect the tender flower buds below from harsh winter cold, late spring frosts, and damaging winds.

If you are in a colder region, then this is certainly something to consider. However, if you want your hydrangea plant to be neat, then removing the faded blooms is something you’ll want to do.

Deadheading Hydrangeas that Flower on New Wood

Smooth hydrangeas (H. arborescens) and panicle hydrangeas (H. paniculata) on the other hand both bloom on new wood.

This means that both the above varieties of hydrangea shrubs produce their flower buds on the new growth of the current season. Because of this, there is much less chance that by deadheading your faded flowers, you will remove developing flower buds!  

You can therefore carry out this job at any time of year (except, of course, during the summer when the plant is coming into flower). Normally, hydrangeas flower on new wood flowers later in the season because they have to produce the stems and the flowers all in one season.

You may have a hydrangea that blooms on both new and old wood. These are newer cultivars of the bigleaf hydrangea, H. macrophylla and have the ability to flower all summer.  The most commonly available is Hydrangea Endless Summer. 

With this type of hydrangea, you should carefully cut off dead hydrangea blooms during the summer.

This hydrangea flowers first on its old wood, and then on the new wood. So you need to take care to cut off the first flush of faded blooms as early as possible. Cut as close to the flower head as possible, to avoid harming any of the following year’s flower buds that will be developing below the flowers.

Once the second flush of flowers has finished, you can safely remove them, as these will have formed on new wood.

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