ASK MARTHA: The ABC’s of Shrub Pruning

Question: Hi Martha, When do I prune my shrubs? Is it ok now?

Martha: Spring is the perfect time to prune certain shrubs; those grown for foliage, including juniper and yew. It’s also a good time to trim plants that flower late in the year on branches produced during spring, such as roses, hibiscus, and buddleias.

However, it’s not the ideal moment to prune shrubs that flower in spring, such as forsythias, azaleas, lilacs, hydrangeas and rhododendrons. Their overall vigor won’t suffer if you prune them, but blooming will be compromised. These shrubs are best pruned right after they finish blooming, so they’ll have the longest possible growing period next year.

Even if you had pruned your shrubs in fall, they may have suffered winter damage, in which case they would need to be pruned again. Damage in the form of broken branches or insect infestation on any shrub should be cut back during spring.

Make straight cuts, exposing as little surface area as possible on the branch ends to minimize recovery time.

Clipped hedges can be used like pedestals, to set off the sculptural shapes and textures of other shrubs and trees' natural growth patterns.

Shrub Pruning

Shrubs offer an endless variety of profiles and silhouettes, and many shrubs may be clipped into precise, geometric shapes. In wintertime, when so many other garden plants have died or retreated underground, shrubs play a starring role in our landscapes.

Whatever the reason, taking up the pruning shears or saw paralyzes even veteran gardeners.

Two thoughts, though, should take much of the anxiety out of pruning:

First, recognize that pruning is inevitable. If you don't make the cuts, it will be a storm that carries away a weak branch or shortens the trunk that has grown too long. Leave deadwood on a shrub, and wood-decaying fungi will take it off. If you don't prune, these natural agents surely will, but they will also remove branches in ways that traumatize or kill the plant.

The second thing to keep in mind about pruning is that it's easy to do right. Before you set to work on any shrub, make sure you understand the growth patterns of that particular species. Understand the shape - conical, mounded, creeping, etc.- that the shrub naturally adopts, and try to enhance it with your cuts. Understand, too, how the shrub grows, whether new growth springs from the tips of its branches or from the base of the trunk, and whether it is new twigs or old that will produce the flowers, fruits, and colorful bark you want. Understand these things, and each shrub will tell you how to prune it.

Maintenance Pruning

To be most effective, shrub pruning must be a regular feature of your gardening schedule. A consistent program of minor cuts - maintenance pruning - allows you to direct the growth of these plants into a healthy pattern. By giving each shrub a few minutes of attention annually, you can usually forestall the need for major surgery down the road. In this way, you'll save yourself a great deal of work while protecting your shrubs against the traumas of drastic cuts and large wounds.

Timing is important

Pruning in late winter or early spring, right before a shrub emerges from dormancy, generally causes the least trauma to the plant. Northern gardeners, though, usually wait for new growth to appear so that they can identify winter-killed branches. The right pruning schedule can also enhance flowering. To promote the best bloom, it's usually wise to prune spring blooming shrubs after they flower, and summer and fall-blooming shrubs as they emerge from dormancy. There are exceptions, so be sure to check recommendations for specific shrubs in the pruning chart below.

Remove the three Ds

Dead, damaged, and diseased branches - it's important to remove them all.

Trim crossing branches

Cut out one of any pair of crossing branches that overlap and rub against one another; the wounds this friction causes offer an entry for diseases and pests.

Relieve crowding

Cut off at the base any branches that are growing back into the center of the bush. As the wind tosses them, they injure the canes and branches around them. They also provide a hiding place for insect pests and a perfect nursery for fungal diseases.

Prune young shrubs

While the shrub is young, prune it to create an armature of well-spaced, spreading branches. Visualize the shape that your species of shrub characteristically adopts and select the branches on the young shrub that promise to fit that profile nicely as they grow. Remove at the base any other branches that crowd or compete with your selections. After the first or second pruning session, the structure should be well established, and this part of the pruning process should require no more than a few snips every year.

Remove suckers

Some types of shrubs, including most roses, commonly sprout new shoots, or "suckers," from the point where the stems join the roots, or from the roots themselves. With ungrafted plants, suckers can be used to renew declining specimens (see "Renewing Neglected Shrubs," below), but if allowed to multiply unchecked they soon turn a shrub into a thicket. Therefore, remove most of the suckers as they appear, leaving only those desired as the source of a new trunk or stem.

Feed and Mulch

Once you have pruned your shrubs, it’s time to feed and mulch. These activities are not just for flower and vegetable gardens. Fertilizing your shrubs in the spring should be part of a maintenance program. Miracle-Gro® Shake 'N Feed Flowering Trees and Shrubs Plant Food is a slow-release granular food that contains natural ingredients to feed microbes in the soil. It can be used on all flowering trees, shrubs, and other acid-loving plants.

Mulch, especially a layer of fluffy organic matter, insulates the soil, keeping the summer sun from heating it to a temperature that would inhibit root growth. In addition, by blocking the evaporation of water off the soil surface, mulch is a great aid to water conservation.

In addition to all the horticultural benefits it provides, mulch can also be decorative. Tucked in neatly around the plants, it's like a fresh coat of paint on a house, giving the garden a finished look.

Miracle-Gro Organic™ All Natural Mulch is an excellent choice; made from dye-free sustainable wood and recycled green waste it is safe to use around kids and pets. Spread one to three inches around your trees and shrubs, being careful to leave the trunks of shrubs clear.

When a branch is broken, cut it cleanly to remove the damaged segment.

Use a pruning saw to cut off crowded stems or trunks that are too thick for shears to handle.

Take out branches that grow into the center of the shrub.

How to renew neglected shrubs

Age brings a handsome maturity to shrubs, but eventually, stems thicken, growing less flexible and gradually losing vigor, so that they bear fewer flowers and fruits. In most cases, it's easy to reverse this decline by forcing the shrub to replace its failing stems and branches with new growth. Be careful in attempting to renew dwarf conifers, since many needled evergreens generate new growth from the tips of existing branches.

1. Check the guide below to determine whether a shrub sprouts suckers, (new shoots), from the base of stems or from the roots. If not, cut back overage stems to a side branch to force out new growth.

2. Some fast-growing suckering shrubs, such as shrubby dogwoods and willows, respond well to a drastic approach: In early spring, all old stems are cut back to ground level.

3. Other, slower-growing suckering shrubs, such as lilacs and spireas, respond better to a gradual treatment whereby one-third of the old stems are removed each year for three years in a row. Cut older stems to the ground after selecting a sucker to keep as its replacement. Thin additional suckers to prevent congestion. If a shrub has no existing suckers, fertilize and prune stems back to a side branch to encourage suckering; begin renewal the following year. Fertilize with Miracle-Gro® Tree & Shrub Plant Food Spikes.

4. With older climbing roses, remove one old cane each year, in early summer right after the first flush of flowers fades. Tie in a flexible young cane as its replacement.

Martha's Shrub Pruning Guide

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Article by Martha Stewart, as part of the Growing with Martha Stewart partnership.