Depending on the kind you have, you must prune your hydrangeas correctly. Different hydrangea varieties need to be pruned at various times of the year.
For instance, you should hold off on pruning smooth hydrangeas like Annabelles until they are through blooming. All summer long, new blooms will result from pruning done in the late fall or early spring, before new growth starts.
Big Leaf and Oakleaf hydrangeas should only be pruned in the early fall to avoid cutting off buds that might otherwise prohibit summer blooming. It’s advisable to prune these hydrangea varieties as soon as they finish blooming.
Although Paniculata or PeeGee hydrangeas are a little more adaptable, they should still be clipped in the early spring before new growth starts.
In Ontario, when should hydrangeas be pruned?
Early in the summer, oakleaf hydrangeas typically bloom earliest. Above a pile of huge, textured leaves in the shape of oak trees, they bear large, white, cone-shaped blooms on robust, cinnamon-colored stems. In the fall, the flowers frequently take on pink or crimson hues before turning rusty brown for the winter. Oakleaf hydrangeas typically do not rebloom. While mature oakleaf hydrangeas in bloom are a joy to behold and will be a pleasure for decades to come, they do grow more slowly than other varieties.
Because oakleaf hydrangeas establish their flower buds for the following summer in the leaf axils of the stems the summer before they bloom, they place their flower buds on ancient wood. The enormous terminal bud at the top of the stem and several smaller buds in the leaf axils down the stem are already formed for the following year in the close-up photo above, which was taken in October.
The majority of shrubs that flower on old wood need to be clipped as soon as the flowering is over. However, because they finish blooming so late in the season, hydrangeas that grow on old wood don’t have enough time to grow back and develop flower buds for the next year when they are pruned after they have flowered. Because of this, we advise against pruning this variety of hydrangea other than to remove any branches that are entirely dead in the spring after the plant begins to leaf out. All oakleaf hydrangeas, non-reblooming bigleaf and mountain hydrangeas are a few examples of hydrangeas that only bloom on ancient wood.
When the plants have gone dormant in late fall or in the early spring, hydrangeas that bloom on new wood can be cut without harm. There is no chance of damaging the flower buds if you prune in the fall or spring because the flower buds for the following year won’t form until late spring of the same year they bloom. If you enjoy the wintertime appearance of dried hydrangea blossoms in your garden, keep them on and prune them in the spring. Prune them in late fall or early winter if you live somewhere with a lot of snowfall or if you prefer a neater appearance in winter. Examples of hydrangeas that only bloom on new wood include panicle and smooth varieties.
Hydrangeas that rebloom have flowers on both old and fresh wood. Because of this, it can be challenging to prune them at a period when no blossoms would be lost. Reblooming cultivars should be pruned similarly to hydrangeas that bloom on old wood, so once the plant begins to leaf out in the spring, you should only need to remove a few (if any) dead branches. Reblooming bigleaf and mountain hydrangea types are two examples.
In general, it is okay to prune hydrangeas that bloom on new wood up to one-third. It is permissible to prune up to two feet from the top and sides of a hydrangea that is six feet tall, for instance. For two reasons, we do not advise trimming more severely than 30%:
- By further pruning it, too much of the strong structure that supports the plant’s erect posture is lost.
- The plant must maintain a sufficient amount of leaves to produce enough food to sustain the root system.
Make your pruning cut immediately above a group of substantial, healthy leaves. A branch can be totally removed if it is dead or broken. Don’t prune if you’re unsure! No hydrangea needs to be pruned in order to flourish and expand.
It’s a popular misperception that hydrangeas can be pruned to keep them shorter all year long. Avoid doing it to avoid potentially removing the flower buds. Your hydrangeas will grow back to their previous size or even larger because trimming encourages new growth, thus it is ineffective to prune them to lessen their height. Instead, move your overgrown, dormant hydrangea to a different location in the early spring and swap it out for a kind that naturally remains shorter.
How far back may a hydrangea tree be cut?
I have a hydrangea tree, but because the branches are excessively long, they bend downward to the ground when it rains. Can I prune branches back, and if so, when should I do it?
Yes, you can prune it, but first it’s important to define a hydrangea tree so you can understand how and why.
A panicled or PG hydrangea (Hydrangea paniculata) is actually a hydrangea tree that has been deliberately pruned to resemble a tree. Depending on the cultivar, it develops huge, elongated clusters of white or lime-green blooms at the tips of its branches in the summer that progressively turn pink or even scarlet in the fall. Since few other kinds of hydrangea have stems robust enough to create decent trees, it’s very much the only one used in this method.
The panicled hydrangea typically develops into a sizable multi-stemmed shrub. It grows an abundance of branches from its base and develops an erect, spreading shape over time, eventually reaching a height and diameter of up to 15 feet (5 meters) after 15 to 20 years. It’s obvious that it’s a shrub because it doesn’t resemble a tree in its natural state.
The nurseryman selects a young specimen with a strong central branch and starts to shape it into a hydrangea tree “prune it until it yields. He cuts off any more branches and any secondary branches that develop on the branch that will eventually serve as the trunk. During the first few years, staking is frequently required to maintain the trunk’s strict verticality. He starts trimming the top of the plant as well after the trunk has grown to the appropriate height, which is often 4 to 5 feet/1.2 to 1.5 meters. Because of this, the hydrangea is compelled to grow numerous branches at the top of a primary stem, or new trunk.
The process of making a hydrangea tree is time-consuming and significantly raises the price of the plant.
If you like, you can prune a hydrangea by yourself to resemble a tree, but it will take some time.
If you want to keep a hydrangea tree healthy, you’ll need to be prepared to prune it on a regular basis. If you don’t, the branches will grow too long and begin to bend under their own weight, as you’ve seen, and they may even break off, especially when there is heavy snow on top of them.
In your situation, it would be advisable to prune your hydrangea tree before winter because it is overgrown and the limbs are already bending from the weight of the plant. Simply prune all branches back to a distance of 6 to 8 inches (15 to 20 cm) from the top of the trunk in October or November if you don’t want them to risk breaking off in snowy or icy conditions.
Starting pruning early in the spring as opposed to the fall will help your hydrangea tree survive the winter. This is because you’ll want to keep the panicled hydrangea’s dried flower heads until spring because they are lovely over the winter.
Make it a practice to trim back all the branches early in the spring, before the leaves emerge, by 6 to 8 inches (15 to 20 cm). This will give your tree the intended effect, which is typically a ball of greenery topped with blossoms at the summit of a short trunk. Panicle hydrangeas bloom from new growth that begins to appear in mid-spring, so they will continue to bloom profusely even after harsh early-spring trimming.
In order to keep its tree-like look, with a clearly “Remove any suckers that develop at the plant’s base and any growth that develops on the trunk itself. This type of pruning is suitable for all seasons.
The optimal growing conditions for panicled hydrangeas are full sun or very little shade in virtually any well-drained soil. They can thrive in zones 3 to 8 and are cold hardy.
Do I need to trim my hydrangea back for the winter?
If and when you prune is the key to happy, healthy hydrangea flowers. Of course, fertilizing and offering the ideal environment have a lot to recommend them. However, if you don’t prune properly, your efforts will be in vain. Deadheading is not the same as trimming. Pruning refers to more drastic cutting to preserve shape or remove dead growth. However, feel free to discard spent blossoms or cut fresh ones to use in arrangements.
Hydrangeas can bloom on either fresh wood or old wood, depending on the species. The wood from which they blossom determines whether and when to prune.
Old wood-blooming hydrangeas do not require pruning and benefit from it. They’ll blossom more abundantly the next season if you leave them alone. But feel free to deadhead or gently thin. Just keep in mind that while new growth may appear, it won’t bloom until the following season. In our region, four different species blossom on aged wood. Additionally, they are not limited to the hues displayed here.
Climb using suckers. On your wall or trellis, resist the desire to remove the dormant growth.
The flower heads are more conical in appearance, and the leaves are large and resemble oak leaves. It’s a pleasant surprise for a hydrangea when its leaves turn reddish-orange in the fall.
They are very comparable to lacecap types, but smaller and with more compact leaves.
Pruning should be done in late winter or early spring on hydrangeas that bloom on new wood. Trim back to two feet to prune to shape. The next season’s blossoms are produced by strong, fresh growth that is encouraged by trimming. In our region, there are two types that bloom on fresh wood. They are also not restricted to the colors displayed.
Oakleaf variants are not included in cone-shaped blooms. Keep the blooms on throughout the winter to provide interest; even dried out, they are quite lovely.
regarded as a wild kind. They often have smaller blooms and leaves than Bigleaf variants and are completely white. They enjoy full sun and can grow very tall.
Knowing whether or when to prune now will help you avoid the disappointment of a hydrangea that doesn’t blossom. Don’t forget that a robust shrub will produce more gorgeous blossoms if it has well-draining soil and good organic fertilizer. Come on in, and we’ll show you where to go to develop your green thumb.
Shape of the Flower Head
- A paniculata type is most likely present if the flower head is formed like a cone.
- It is either a macrophylla or an arborescens kind if the flower head resembles a ball or a flat disk. Visit the section on Flower Color.
Robert Pavlis’ photograph of a hydrangea arborescens from the side, highlighting the flower’s dome-shaped crown
Flower Color
- A macrophylla type is present if newly opened blooms feature blue, purple, or pink blossoms.
- An arborescens type is present if the flower buds initially seem green, then turn white, and finally turn green or greenish brown as they ripen.
- You likely have a macrophylla kind if the flowers are white when they first open and remain white as they age. Although they are less common, white flowered macrophylla varieties do occur.
Note: Recent breeding is beginning to develop arborescens with flowers that have a pink tint, such as “Eco Pink Puff.” Future cultivars should have a stronger version of this pink.
Cut back these shrubs in late winter before new growth begins
Shrubs that flower on young wood typically start blooming later than old-growth bloomers, beginning in June and continuing until the first frost, because they need to grow and set buds the same year that they bloom. As long as you avoid trimming when the flower buds are opening, these shrubs are understanding if it is not done at a specific period.
1. Trim the flowers all the way back for larger blooms.
These bushes can be completely removed from the ground in late winter or the beginning of spring. If cut severely like this every year, smooth hydrangeas will produce much larger flowers, but many gardeners prefer smaller blooms on stronger stems.
2. Maintain an old growth foundation to lessen flopping
Especially after watering from above or after a heavy storm, the branches of some hydrangeas frequently topple over from the weight of their blooms. Cutting the stems to a height of 18 to 24 inches will help to reduce this flopping by creating a strong framework for fresh growth.
Janet Carson is the University of Arkansas Cooperative Extension Service’s horticulture specialist.
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