How to Prune Flowering Shrubs
By Arlington Parks & Recreation
Posted on April 24, 2020, April 24, 2020

pruning a bush

It’s spring and gardening season is in full swing! Pruning your shrubs is an important part of keeping them healthy and beautiful, but it can be tricky to determine when you should cut back your shrubs. For example, there is a big difference between spring flowering shrubs and summer flowering shrubs and the appropriate time to prune each of them. Cutting them back at the wrong time could potentially reduce flower production in the following year, or could even keep the plant from flowering at all. Thankfully, APRD’s Urban Forestry Land Manager, Wendy Pappas, is here to offer this helpful advice about shrub pruning.

Spring Flowering Shrubs

Most spring flowering shrubs should be pruned quickly after they are finished flowering. The reason for this is because these shrubs develop their flowers on wood from the summer and fall. If these are pruned after flower buds have developed, it will reduce flower production for next spring. Spring flowering shrubs are best pruned by removing the largest stems at ground level. In turn, the plant will form new growth from the ground up, and this will also prevent the plant from growing too tall. After removing the oldest stems from ground level, you can prune to remove damaged or diseased limbs. Lastly, you can prune for height and shape to your liking. Make sure to avoid over-pruning; you should never remove more than 1/3 of the plant for best results.

Some examples of spring flowering shrubs include: Forsythia (Forsythia), Viburnum (Viburnum), Mock Orange (Philadelphus), Bridalwreath Spiraea (Spiraea prunifolia), Big Leaf Hydrangea (Hydrangea macrophylla) and Lilac (Syringa).

Summer and Fall Flowering Shrubs

Unlike spring flowering shrubs, summer and fall flowering shrubs flower on new growth rather than old wood. This means you can prune all the way to the ground to rejuvenate the plant, or you can prune the old growth selectively. Pruning these plants back to a bud is ideal for ensuring new plant growth. For summer and fall flowering shrubs, be sure to avoid pruning right before winter.

Some examples of summer and fall flowering shrubs include: Butterfly Bush (Buddleia davidii), Hydrangea paniculate (Hydrangea paniculate), Rose of Sharon (Hibiscus syriacus), Spirea (Spiraea japonica), and Roses (Rosaea).

Evergreen Flowering Shrubs

Evergreen flowering shrubs need a unique kind of pruning for optimal appearance and health depending on the variety of plant. For old-fashioned azaleas that flower in the spring, pruning should take place right after flowering. There are other varieties of azaleas that flower in both the spring and the fall. For these, it is best to prune only the old branches all the way to the ground, while being careful to not remove more than 1/3 of new growth. Some other evergreen flowering shrubs include mountain laurel and winter heath. Mountain laurel grows at a slow rate and should not need much pruning, though dead and broken branches can be removed any time. Winter heath should be pruned right after flowering.

Examples of evergreen flowering shrubs include: Azalea (Rhododendron sp.), Mountain Laurel (Kalmia latifolia), and Winter Heath (Erica carnea).

Evergreen Nonflowering Shrubs

Evergreen shrubs that do not flower can be pruned and sheared at any time throughout the year. These shrubs can be formed into almost any shape you can think of. If you would like your plant to maintain a certain shape or design, a shave or trim will be necessary several times throughout the year.

Examples of evergreen nonflowering shrubs include: Boxwood (Buxus sempervirens) and pretty much any type of Holly (Ilex sp.).

We hope you enjoy these pruning tips from the pros at APRD’s Forestry and Beautification team. These techniques are sure to keep your shrubs looking beautiful and healthy all year round!

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