by Cindy King, CPH, The Mill Horticulturist
Pruning is a vital part of plant health and garden maintenance. Knowing when to prune shrubs—and how different plants respond—helps you encourage blooms, manage plant size, and support long-term health. Here's a guide to pruning plants in your garden, broken down by plant type and bloom time.
Pruning Spring-Blooming Shrubs
Many deciduous shrubs like Chaenomeles (flowering quince), Viburnum, Aronia,
Edgeworthia, Lilac, Forsythia, and Azalea bloom in early spring. These shrubs bloom on old wood—meaning flower buds are set the previous season.
🔹 When to prune: Prune immediately after flowering to avoid cutting off next year’s flower buds.
🔹 What to consider: If you enjoy the fruit set on Viburnums or Aronia—either for harvesting or feeding birds—skip pruning to preserve the berries.
🔹 How to prune:
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Thin by removing older limbs or branches growing toward the center to improve air circulation and reduce disease risk.
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Tip back growth by cutting just above a leaf node to shape the shrub. Keep in mind: increased tip growth can shade the plant’s center, causing inner leaves to drop.
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For suckering shrubs like Forsythia, rejuvenation pruning (removing older canes to the ground) helps manage size and stimulate new growth.
Pruning Early Summer Flowering Shrubs
Shrubs like Hydrangea macrophylla, Spirea, Fothergilla, Calycanthus, Hydrangea arborescens, and Hydrangea quercifolia bloom in early summer. These typically flower on old wood and should be pruned with care.
🔹 When to prune: Prune just after flowering. Avoid removing large flower buds.
🔹 Remontant hydrangeas, which bloom on both old and new wood (e.g., Endless Summer, Wee Series, and Let’s Dance Series), should only be lightly pruned. Just remove spent blooms to encourage continuous flowering without removing next season’s buds.
Pruning Late Summer Bloomers
Late summer flowering shrubs like Hydrangea paniculata, Buddleia (butterfly bush), Abelia, and Ceanothus bloom on new wood—the growth produced in the same season.
🔹 When to prune: Prune in late winter to early spring, before new growth starts.
🔹 How to prune:
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Open the plant up for airflow.
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Reduce the overall size by one-third, cutting to a node or healthy leaf bud.
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Remove dead, crossing, or diseased branches for a clean, healthy structure.
How to Prune Evergreen Trees and Conifers
Evergreens like White Pine and Norway Spruce require a different approach, especially when size control is important.
🔹 White Pine (candle-forming):
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Prune candle growth (new shoots) by up to three-quarters of their length to control size and shape.
🔹 Spruce and needle-cluster conifers:
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Prune just above a bud that faces outward using a 45-degree angle. This promotes water runoff and encourages new growth to expand outward, increasing sun exposure and balanced form.
Why Proper Pruning Matters
Pruning is more than shaping your plants—it's a critical aspect of their health. It reduces disease risk, improves air and light circulation, and ensures your plants look their best throughout the growing season. Whether you're working with flowering shrubs, remontant hydrangeas, or evergreens, understanding the right pruning methods will help your garden thrive.
