Most trees and shrubs benefit from annual pruning. It keeps them in shape, gets rid of dead and diseased wood and encourages new growth. Spring may seem like the ideal time to do this and we are all certainly ready to get out in the garden and start to clean things up. But not all trees and shrubs should be pruned early, especially some of the flowering ones.
How to Decide When to Prune Flowering Trees and Shrubs
Early spring bloomers set their flower buds the previous fall. Pruning these plants early in the spring would mean pruning off the flower buds and losing some, if not all the blossoms. It is also one of the most common answers to "Why don't my plants bloom?.
A general rule of thumb is to:
- Prune spring flowering trees and shrubs right after they bloom
- Prune later flowering trees and shrubs in the early spring.
This helps guarantee the plants will have time to set new buds and that they will flower for you next season.
Most of the time losing an entire season of flowers is not what you want to accomplish with pruning. However, sometimes it is worth it. When you need to rejuvenate an old tree or shrub and make extensive cuts, it’s much easier to prune when you can see the shape of the plant. In that case, it would mean pruning while the tree or shrub is dormant before it leafs out and the branches are masked by leaves. Trees and shrubs that are in need of a good shaping can do with sacrificing a few blooms for one year, to be invigorated by a spring pruning.
Pruning during a tree or shrub's dormant season offers a couple of additional perks that are worth considering. Any kind of pruning stresses a plant. If you prune while the tree is trying to actively grow in the spring, it is even more of a burden. Dormant pruning allows the tree or shrub to deal with healing the cut, without having to worry about producing leaves and flowers or sending out new growth.
Another plus is that winter pruned plants are less susceptible to insect and disease problems. Pruning creates an open wound. Although the tree or shrub is perfectly capable of healing itself, it can take several days. In the meantime, that open wound is an invitation for insects, bacteria and fungal spores to get inside the plant. Since most insects and diseases are not active in cold, winter weather, the tree or shrub has time to recoup without the extra stress of fighting off a potential problem.
New Hydrangeas Can Be Pruned Anytime
To make things easier for you, most of the new varieties of hydrangeas have been bred to repeat bloom throughout the growing season. They tend to bloom on the new growth, so no matter when you prune, more flowers buds will be set and the flowers will follow. So if figuring out when to prune which shrub is too confusing for you, look for a modern hydrangea, such as the Endless Summer® and Everlasting® series.
Although there are rules of thumb, there are no hard and fast rules. To help you out, here is a list of commonly grown spring flowering trees and shrubs and the best time to prune them.
Trees and Shrubs to Prune in Late Spring/Early Summer, After Bloom
These trees and shrubs set their flower buds the prior fall and adhere to the rule of thumb to hold off on early spring pruning, until after their flowers fade. You'll have a couple of weeks grace period, after flowering, to get this pruning done before next seasons buds begin being set.
- Azalea (Rhododendron species)
- Beautybush (Kolkwitzia amabilis)
- Bridal Wreath Spirea (Spirea x vanhouttei)
- Flowering Crabapple (Malus species and cultivars)
- Forsythia (Forsythia x intermedia)
- Hawthorn (Crataegus species and cultivars)
- Hydrangea, Bigleaf (Hydrangea macrophylla)
- Lilac (Syringa vulgaris)
- Magnolia (Magnolia species and cultivars)
- Mockorange (Philadelphus coronarius)
- Mountain Laurel (Kalmia latifolia)
- Rhododendron (Rhododendron species)
- Serviceberry (Amelanchier x grandiflora)
- Slender Deutzia (Deutzia gracilis)
- Weigela (Weigela florida)
Trees and Shrubs to Prune in Early Spring, While Dormant
These trees and shrubs don't usually set their flowering buds until they start actively growing in spring. They should be pruned as early in the spring as possible, while they are still dormant, to give them time to recover.
- Bradford Pear (Pyrus calleryana)
- Butterfly Bush (Buddleia Davidii)
- Crape Myrtle (Lagerstroemia indica)
- Flowering Dogwood (Cornus florida)
- Flowering Plum (Prunus blireana)
- Glossy Abelia (Abelia x grandiflora)
- Golden Rain Tree (Koelreuteria paniculata)
- Honeysuckle (Lonicera fragrantissiam)
- Hydrangea, Peegee (Hydrangea paniculata ‘Grandiflora’)
- Potentilla (Potentilla fruticosa)
- Redbud (Cercis canadensis)
- Spirea (except Bridal Wreath) (Spirea japonica))
- Wisteria (Wisteria species)