Pruning shrubs, when to cut and how much

When to prune a shrub depends on when its flowers form. Shrubs that bloom in summer flower on the current year's growth, so pruning before spring growth starts doesn't cost any flowers. Shrubs that bloom in spring set their buds the year before, so pruning them in winter cuts off that spring's flowers. Late winter to early spring is the best time for most other pruning. Severe pruning in late fall or midwinter can push out new growth that cold weather injures.

What you need

• Hand pruners, for stems up to 3/4 inch thick
• Loppers, for branches up to 1 1/2 inches
• A pruning saw, for branches too thick for the loppers
• Gloves

Steps

1. 1

   Check when the shrub blooms

   Summer bloomers such as butterfly bush, rose-of-Sharon, glossy abelia and Japanese spirea get pruned before spring growth. Spring bloomers such as azalea, forsythia, mockorange, weigela and bigleaf hydrangea get pruned right after they flower.

   5 min

2. 2

   Take out the dead wood first

   Cut out every dead, diseased, broken or injured branch.

   10 min

3. 3

   Remove rubbing branches

   Where two branches cross or rub, remove one of them completely at its base. Take out branches that grow downward or look out of place.

   10 min

4. 4

   Thin the oldest stems

   If the shrub is still too dense or too big, cut a few of the oldest, thickest stems at the ground. Taking out up to a third of the old stems each year renews a shrub over three years without losing it all at once.

   15 min

5. 5

   Shorten what's left at different heights

   Cut back long shoots to a side branch, or about 1/4 inch above a bud on a slight slant. Use a bud that faces out, so the new branch grows away from the center. Cutting to several heights keeps the shrub from getting thick on the outside and bare inside.

   10 min

6. 6

   Shape a hedge wider at the base

   Trim a hedge so the bottom is wider than the top. A narrow base gets shaded by the top and loses its lower leaves.

   10 min

7. 7

   Check that the cuts are hidden

   Step back and look. A well-pruned shrub doesn't look pruned, with the cuts tucked inside under the remaining leaves.

   2 min

Thinning instead of shearing

Thinning cuts take whole branches back to a side branch or to the ground. They let light into the middle, reduce the size and leave a fuller plant. Shearing the tips all over, called heading back, makes dense growth at the outside, which shades the inside until it goes bare and stemmy. Most shrubs look best in their natural form. Save tight geometric shearing for a formal hedge, and clip it while the new growth is still green and soft.

Cutting an overgrown shrub way back

Some overgrown broadleaf shrubs can be cut to 6 to 12 inches from the ground, called renewal pruning, before spring growth begins. Azaleas, camellias, privets, glossy abelia and nandina respond well, and grow back by midsummer. Trim the tips once the new shoots are 6 to 12 inches long to make the shrub bushier.

Boxwoods, junipers, yews, arborvitae, pines and other narrow-leaf evergreens don't come back from severe pruning and may decline. For these, take the old stems out a third at a time over three years.

Leave these to a professional

Prune only what you can reach from the ground. Taller hedges and shrubs and large trees are jobs for a tree care professional. A branch near an electrical or utility wire is one for the utility company. Never use a chainsaw above shoulder height or from a ladder.