The basics of pruning

Pruning is simply removing a part of a plant (branches, leaves, buds or roots) and can be done at different times of the year to achieve different results. The general rule is that spring pruning encourages growth, whereas summer pruning suppresses growth.

Why prune?

Pruning can improve the health of a plant, improve the look, and remove disease. It can also encourage new growth. Generally (though of course there are exceptions), don’t prune more than 30% of the plant. A general rule: If the plant flowers before June 1st, prune it during or shortly after flowering.  If it blooms after June 1st prune it in the late winter or early spring before flower buds are visible.

What to prune, when

Flowering trees, shrubs and vines: Late winter or early spring

Fruit trees and berry plants: When dormant

Evergreens: Early spring or don’t prune

Perrenials: Fall or spring (depending on the kind)

Trees and shrubs

Most shrubs, fruit trees, and shade trees can be pruned in the early spring or winter while they are still dormant (before March), but some trees will bleed sap if they are pruned in the spring, so prune them in the summer or in the late-fall except stone fruit trees, which should be pruned in late winter.

There are basically three types of pruning, (but really only two for most plants) dormant season pruning, summer pruning and fall pruning.

Dormant season pruning

This will stimulate new growth and can be done in the winter or early spring before new growth appears. It's the best time to prune young trees, or correct problems in older trees.

Summer pruning

This will not stimulate as much new growth, and can be done to control the size, or if you want to avoid too much growth (like on an espalier tree).

Autumn pruning

Most Trees and plants don’t like being pruned in fall because it may promote new growth that won’t  be hardy enough to survive the winter, and since the tree/plant is trying  to hunker down (not grow) pruning cuts probably won’t heal. Exceptions include perennial plants that are winter hardy and like being totally cut back.

Spring and summer flowering 

If your main goal is to have as many flowers as possible, wait until after it is finished blooming to prune. (lilac, forsythia, wisteria, bridal wreath spirea, flowering cherry, flowering pear, flowering plum, redbud, quince, etc.), and prune them right after they finish blooming. If you wait too long to prune them, you will be removing next year's blossoms. 

Prune summer flowering plants any time while they are dormant. (Weigela, hibiscus, potentilla, etc.)

Pruning plants.

Most perennials (and hardy ferns) can be pruned in the fall, or in spring (if you want to keep the seeds for wildlife, like I do). Any evergreens can be pruned in spring before new shoots appear.

Plants that die back in winter (hostas) can just be tidied up in the spring (i.e. just put the dead leaves onto your compost.

Annual flowers don’t need to be pruned at all, because they die off every year.

How to prune

ALWAYS prune back to or just above a growing point (branch or bud) or to the soil line. NEVER leave a stem or branch stub.