Pruning hydrangeas is both complex and confusing. Some require spring pruning and others need cut back in the late winter. Knowing when to prune hydrangeas has become a dilemma for many gardeners. Interestingly, you should not feel an urgency to grab the shears and start cutting because the shrub can flourish without frequent trimming. Improper trim timing can lead to a lack of booms or a subpar display. However, if you can learn to hit the sweet spot by determining the perfect time of the season to cut back the shrub then you’ll increase the size and number of the plant’s blooms.
If your hydrangea blooms on old-growth wood then do not prune until after it has completed its flowering process. Prune hydrangeas that bloom on new growth during the early spring or right before fall dormancy.
Does your hydrangea bloom on old wood? You’ll need to study your plant if you are unsure of what variety is growing in your garden. Does it develop flowers early in the season? As the summer progresses, do the blooms become more sporadic? Such hydrangea shrubs start to form their flower buds in the late summer or autumn when the shorter days and cooler weather triggers production.
You do not want to prune hydrangeas that bloom on the old wood in the autumn or spring because then you’ll have very few blooms the following season. Instead, prune hydrangeas that bloom on old growth stems right after the shrub produces blooms before it has a chance to start developing its buds for the following year.
This is also an ideal time to tidy up the shrub by cutting away old canes that have failed to produce any flowers. Cut them back to the soil’s line and discard them to encourage more vigorous new growth. You can also control the shrub’s height by targeting old canes and removing them before they become too leggy.
Hydrangeas that bloom on new growth must set buds on the new canes which takes time. You’ll notice that such varieties take longer to develop flowers than the varieties that set blooms on old growth stems. Also, once they start to bloom, they will continue to blossom until the first frost of fall. Ideally, you should avoid pruning these shrubs when the flower buds are just starting to open, or you won’t enjoy any blossoms for the year.
Prune hydrangeas that flower on new growth in the late winter or early spring months. You can cut the canes all the way to ground level. Severe pruning helps to ensure that the shrub produces large and abundant blooms. However, the stems will be less sturdy. If you live in a wind zone then you might want to not cut the canes to the ground’s level to encourage sturdier stem development and smaller blooms. It is not uncommon for some branches to bend completely to the ground because of the excessive weight of the blooms or after a heavy rainstorm. To prevent the canes from flopping over from the flower’s weight, prune the stems to a height of 18 to 24 inches so they can develop a robust framework that can support the flowerheads.
The Endless Summer variety of hydrangea has the unique distinction of blooming on both new and old wood. The shrub will produce a bevy of lovely blooms during the early spring months and then create more blooms later in the summer and early autumn. The shrub can easily flower all summer which makes it a garden favorite. To prune this variety, you will need to cut away the faded flower stems to about half their length. This pruning method will encourage not only additional bud production but also new growth. Once the shrub produces its last bloom of the season in the autumn then it’s time to prune the shrub to control its height and shape. Just don’t go crazy cutting it back or you could pay with a lackluster flower display the following spring.
The smooth hydrangea H. arborescens is not as showy as standard hydrangeas. The Grandiflora variety does produce an abundance of flowers, but they lack the beauty of other varieties. The shrub’s leaves are also rounded with a pointed tip. They are usually a paler hue of green on the underside than the top side. The blooms of the shrub are produced on new wood so always prune in the early spring. Look for any branches that have sustained an injury during the winter months and remove them. Then only lightly prune the rest of the shrub.
The PeeGee is known for its round, snowball-like flowers that appear white and then slowly change to a soft pink. The flowers develop in large clusters in the mid-to-late summer. Many gardeners like to trim the shrub’s flowers and dry them for arrangements.
All the blooms produced on the PeeGee occur on the shrub’s new growth. You can lightly prune individual stems in the late winter or early spring to control their growth and encourage healthy flower production. Also, as the flowers start to die then you can deadhead the flowers to maintain the shrub’s shape and form. Also, removing the spent flower heads helps keep the plant looking good.
The climbing hydrangea is a sight to behold when in full bloom. The vine typically requires extraordinarily little, if any, pruning. All the flowers are produced on the old growth from the previous season. Once established, the vine grows well and with little care. If you need to control its size then prune it in the late winter. If the vine starts to look neglected or overgrown then you can cut it back to ground level during the early spring to help it rejuvenate but it will probably not produce blooms that season.
Yes, learning when to prune hydrangeas is tricky but if you become familiar with your shrub then you shouldn’t have too much trouble determining the perfect time.