Gardening | Winter Pruning – summer blooming trees and shrubs

Winter pruning during plant dormancy has a substantial impact on spring growth and summer blooms. Late winter pruning before bud break stimulates a burst of growth in spring because new tissue forms quickly. The fresh growth sets the stage for abundant summer flowering.

A number of summer-blooming shrubs can be pruned in winter. Shaping up or reinvigorating your plants is a good reason to prune. Keep in mind, though, it is not necessary to cut back all summer blooming shrubs and trees just because the time is right.

Beautyberry and butterfly bush both benefit from hard winter pruning. Cut them back to a foot or two for abundant new growth and flowering come summer. Pruning in late winter invigorates their spring growth and energizes summer blooms. You will maintain a tidy compact size by pruning to the ground each year.

Lightly trim off seeds and eliminate crossing branches on crape myrtles. If a crape myrtle is too large for its location, replace it with a smaller variety and move the outsized plant to a more suitable location.

Glossy abelia, summersweet clethra, gardenias, hollies, Japanese barberry, ligustrum, lonicera, rose of Sharon, St. John’s wort and tea olives are some of the shrubs that are suitable for winter pruning.

Keep track of when your viburnum blooms. Is it evergreen or deciduous? Generally prune evergreen varieties in winter. However, wait until after plants bloom to prune deciduous species like Chinese snowball viburnum.

Know which varieties of hydrangea and clematis you have in your garden. When you buy these plants keep the tags. Different varieties bloom at different times, some on old wood, and others on new wood.

Group 3 clematis bloom on new wood in summer and fall. Plants can be pruned in late winter.

PeeGee hydrangeas and newer varieties of H. paniculata, like “Limelight” and “Pink Diamond,” should be cut back in February because—plants produce blooms on only new growth. Prune H. arborescens “Annabelle “in late winter. (Be aware that hard pruning produces bigger flowers.) Wait until spring or summer to prune oakleaf and bigleaf hydrangeas.

Awareness of the natural habit of a shrub will help you determine how to prune it. Plan to prune your shrub to help maintain its natural habit, which may be caning, mounding or tree-like.

There are two basic types of pruning cuts, thinning and heading. Each produces a different growth response.

Thinning removes the entire shoot or limb to its point of origin. This is the least stimulating pruning technique, and the best for maintaining the natural shape of a shrub. It opens up a plant to light and airflow. Thinning is also the recommended way to reduce the size of a tree or shrub.

Shrubs like boxwoods, with dense centers, benefit from interior thinning. It improves airflow and allows light into the plant.

Thinning cuts should be made close to a branch collar to avoid leaving stubs, and carefully enough to prevent damage the branch collar. When well done, the cuts, which are largely in the plant’s interior, are barely visible at close range.

A heading cut removes part of a shoot or limb. Shoots grow outward from their tips. Removal of the tips stimulates growth from lower buds, typically near the cut. Make the cut just above an outside bud. That prevents dieback of the stem and encourages branching from the bud. Hedging and topping are both heading cuts.

Most woody plants have an alternate or opposite arrangement of buds on their twigs and branches. How the pair of buds closest to the cut is situated indicates in which direction a new shoot will grow. A bud on top of the twig will grow angled upward. If a bud is on the twig’s side it will grow in the direction it faces. Cut stems back to an outward facing bud; don’t cut back to one that will grow inward and cross other branches.

Dead and diseased wood on trees and shrubs should be removed year round. So should suckers and dangerous limbs. Light pruning of branches that obstruct walkways or obscure a view is also appropriate anytime.

This story was originally published January 29, 2016 at 7:00 AM with the headline "Gardening | Winter Pruning – summer blooming trees and shrubs."