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10 Tips Before You Prune

Winter is a great time to see the architecture of trees and bushes without the leaves. When temps are above freezing as the ice and snow melts, look for crossing branches and dead, diseased, or damaged wood. Removing these will improve air and light circulation and may help to reduce damage from winds, storms and heavy snows. Trees pruned in early spring develop a callous around the cut much more rapidly than those pruned at other times.

 

Pruning Basics

Twigs and Small Branches

  • For twigs and small branches under ½” in size, cut back to a viable bud or intersecting branch. If you choose to cut back to a bud, make sure that it is pointing the direction you want new growth to develop.

  • In general, choose a bud facing outwards so the new twig does not grow towards the center of the plant. This may prevent crossing or air circulation issues in the future.

  • Make a clean cut at a 45° angle close to the bud, but not leaving a stub. The twig has special cells in this area so that when cut, the wound will eventually seal itself.

  • If you leave too much of the twig above the bud, the remaining stub will slowly die, becoming an entry point for insects and disease.

Thick Heavy Branches

  • For branches ½” to 1½” in diameter be sure to locate the branch collar before cutting.

  • Look for an area of thickened bark around the base of the branch that extends a little way outward along it.

  • This collar is made up of special cells that will close off a wound over time.

  • It is important not to cut into the collar as it will impair the natural healing process.

  • Large branches should be removed flush with the collar, not flush with the trunk.

 

Tips for Pruning Deciduous Trees & Shrubs

1. Leather gloves, long sleeves, and sharp pruners provide protection and faster maintenance.

2. Clean pruners with alcohol between plants to limit the spread of disease.

3. Prune branches that grow inward or rub on one another to keep growth away from the plant center. Opening up the canopy of a tree or the structure of shrubs will allow greater air circulation and reduce fungal disease.

4. To avoid the introduction of disease pathogens to oaks and elms, prune while they are dormant in late winter. Do not prune these species between April 15 and October 15 while they are actively growing.

5. Maples, walnuts, birches, beeches, hornbeams, and yellowwood have copious sap flow, known as ‘bleeding’ when cut. It is not harmful to the tree. Delay pruning until after the foliage has fully emerged to reduce bleeding.

6. Generally, shrubs can be successfully pruned whenever they are not actively growing. The timing of pruning will help to ensure blooms for next season. Pruning stimulates growth so it is also best not prune after August to avoid winter damage to new growth.

7. Before the end of March, woody plants that bloom in summer, like Clethra, St. John’s Wort, summer-blooming Spirea, and Weigela can be pruned. Before new spring growth begins, prune Alpine Currant, Barberry, Burning Bush, Elderberry, Filbert, Smokebush, Rose of Sharon, Privet, Potentilla, Sumac, and Summersweet.

8. If you like the size and shape of your Hydrangea as it is right now, let it be. Each type of hydrangea has different pruning best practices.

  • Hydrangea arborescens – Smooth Hydrangea: Prune in late fall or early spring to 6″ – 12”. Tip: If you only prune in spring to remove spent flowers, the old canes will help support the new growth of the plant. 

  • Hydrangea paniculata – Panicle Hydrangea: Prune them in early spring to control size. We recommend leaving the dried flowers on the plant to provide winter interest and lightly deadhead them in spring. To maintain a shorter shrub, the canes can be cut back to 6”-12”.

  • Hydrangea quercifolia – Oakleaf Hydrangea: Prune after flowering to control size. Oakleaf blooms on old wood, meaning flower buds are set on last year’s growth, cutting down in spring will remove flower buds for the coming year. Occasionally they will need older, thicker stems removed.

  • Hydrangea macrophylla – Big Leaf Hydrangea: The first set of flowers comes from older stems on the Endless Summer or big leaf Hydrangeas, wait until the leaf buds open before pruning and only remove the dead portions of stems in early spring.

  • Hydrangea serrata – Mountain Hydrangea: Pruning is typically not needed, but it may be pruned to shape immediately after the spring bloom. These hydrangeas also bloom on old wood, meaning flower buds are set on last year’s growth. If you cut down in spring you will remove flower buds for the coming year. 

9. Other shrubs that should be pruned within 2 weeks after flowering include Beautybush, Chokeberry, Cotoneaster, Daphne, Deutzia, Dogwood, Firethorn, Flowering Almond, Fothergilla, Honeysuckle, Lilac, and Viburnum.

10. Bring a bit of spring inside now! Cut branches will come out of dormancy in 2-3 weeks in a vase of water. This is referred to as indoor forcing. Try it with branches less than ½” in diameter from Forsythia, Quince, Cherry, Magnolia, Redbud, Pear, Crabapple, Pussywillow, and even some Maple trees.

Need assistance in identifying trees? Use this Handy Guide from The Morton Arboretum.