Garden Detective: Pruning trees and shrubs

Late winter is the time to prune shrubs Late winter is the time to prune shrubs such as clove currant. Photo Credit: AP

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Jessica Damiano Jessica Damiano, Newsday columnist

Jessica Damiano is a master gardener and journalist with more than 20 years experience in radio, television, print ...

It's late winter, and you know what that means: It's time to prune your trees, shrubs and woody plants.

It's important to do this while plants are dormant and you can see what you're doing. Wait until they leaf out, and your view of the branches will be obstructed. Worse, pruning during the growing phase will stress plants, because energy that should be used for growing and forming leaves and flowers will be halfheartedly redirected to healing. You might sacrifice vigor and blooms for the season, and the plants might not heal properly.

So bundle up, grab your pruners and saws, and head out now.

There are two types of pruning: selective and rejuvenative.

Selective is exactly what it sounds like: You select certain branches to remove, and you have a reason for doing so (branches are crooked and overlapping, broken, crowded).

Rejuvenative pruning is the extreme cutting back of overgrown, unproductive shrubs so they'll regrow stronger, healthier and with a better appearance.

There are three ways to rejuvenate woody plants by pruning: Sever the whole plant at the crown, just above ground level; prune every branch individually, at uneven heights, in one session; or cut back about one-third of the branches each year for three years. The latter is the least severe but requires the most patience. You'll need to weigh aesthetics versus time and decide what's right for your garden.

Most plants can handle selective pruning with ease; only healthy plants should be subjected to drastic rejuvenation. And when you're done, be sure to fertilize to help the healing along.

Here's a primer for pruning the most common types of landscape plants.

Broad-leaved evergreen shrubs (laurels, rhododendrons, etc.) should undergo only selective pruning. They're the exception in that they can handle pruning easily at any time of year.

Narrow-leaf (needled) evergreens should undergo selective pruning only. Always remove more from the top than from the bottom, which will allow sunlight to reach the base of the plant. Take care not to overshear or cut holes into narrow-leaf evergreens; with the exception of yews, they won't ever fill back in.

Hedge pruning has only one basic rule: The bottom must remain wider than the top. If the plant thins out at the bottom, the only way to correct it is to cut the entire hedge down to 6 to 8 inches from the ground and wait for it to grow back. You don't want to go there.

Thin-branched trees and shrubs should be pruned using hand-held pruners to remove dead wood, crisscrossed limbs and branches that are growing into the tree's canopy.

Branches with a diameter of more than one inch should never be cut right up to the trunk. That would remove the branch collar and create a bigger wound. Instead, use a saw and employ the three-cut method:

1. Cut the branch halfway through from underneath, a few inches from the trunk.

2. Move your saw a few inches farther out on the branch, away from the trunk, and cut the whole branch off from the top. This eliminates the weight of the branch and prevents tearing.

3. Make the third and final cut just outside the branch-bark ridge, sawing through the entire branch to the outside of the collar. If you were to make this complete cut without having done steps 1 and 2, the weight of the branch would cause it to rip just before separating, and the tree would have a difficult recovery and a larger area through which disease could enter.

For lilacs and other spring bloomers, wait until after flowers fall so as not to remove buds and spoil the season's show. Forsythia should be pruned every year right after flowering.

Spirea and

weigela should be pruned every two to three years.

Clethra and cotoneasters should seldom be pruned. Butterfly bush (Buddleia) should never be pruned in fall. Cut it all the way to the ground every year in early spring. Don't worry; it'll grow back quickly.

Deadhead rhododendrons and mountain laurels only if they aren't full enough, and do it immediately after flowering. Waiting even a week will defeat the purpose, and the plants will remain leggy.

Hydrangeas

Hydrangeas are in a class all their own; actually, in several classes. Here are the basics:

Hydrangea macrophylla: Prune in late summer, as soon as flowers fade, but never after September. Remove weaker stems from the base of the plant, being careful to retain several stems of old wood, which will produce buds for next year's flowers. Pruning in late winter will not harm the plant, but it will cost you flowers this year.

Hydrangea arborescens Grandiflora: Cut to the ground in late winter or early spring. If it survived the winter nicely, however, and you'd like it to grow better, do a light selective pruning, cutting branches at varying heights.

Hydrangea paniculata Grandiflora (Peegee): Simply remove spent flowers; thin or cut back last year's growth in late winter/early spring.

Hydrangea quercifolia (Oak-leaf hydrangea): Remove dead wood at the base of the plant in early spring.

Hydrangea anomala petiolaris (climbing hydrangea): Unruly vines can be shortened in summer. Otherwise, pruning is seldom necessary.

 

GARDEN CLUB OF THE WEEK

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Suffolk Orchid Society Meets: 7:30 p.m. on the second Monday of each month from September through June

Location: Emma Clark Library, 120 Main St., Setauket

Dues: $15 annually; $22 family

Contact: suffolkorchids.com; 631-473-8726

This self-described "fun-loving group of orchid enthusiasts" has a simple goal: to "promote and improve the growing of orchids, and aid in every possible way in the conservation of all native orchids." Meetings include member show-and-tell sessions, raffles and sales, and presentations by guest speakers. Plant auctions are held in June and November.

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