Why To Prune
Before pruning of landscape plants happen think about why it is being pruned, what is the goal? Pruning should be done to remove any dead, broken, injured, diseased, or insect infested branches. Pruning should also be done to prune out undesirable branches such as crossovers, suckers, sprouts, or those branches that are too long or too low. Pruning should also happen when the weather is dryer and no rain is in the forecast for the next couple of days. Pruning in moist weather can promote disease in the open wounds. Also, the weather should not be too hot this can stress the plant out and cause unwanted color in the leaves. Around 70 degrees would be ideal.
Spring Flowering Trees & Shrubs
Pruning for those plants whose flowering time is before June 1st should be done immediately after flowering. Pruning later could result in the loss of next season’s bloom. Some examples include: crabapple, deutzia, forsythia, lilac, redbud, serviceberry, rhododendron, viburnum and weigela.
Summer Flowering Trees & Shrubs
Those plants which flower after June 1st can be pruned at anytime, except in the heat of the summer when insects are active. Twiggy shrubs such as potentilla and spirea also benefit from a good “haircut” first thing in the spring. They will bounce back looking fresh and full. These plants may also be lightly trimmed after each flush of bloom to promote re-bloom.
Allow new growth in spring and early summer. In late June, trim back 50-90% of the new growth, being careful to avoid cutting back into older wood. Prune every year to encourage tighter, more compact growth. Allow some new growth to remain every year. Do not prune evergreens in late summer or fall. Any late new growth will be prone to winter damage.
Many trees are best pruned while dormant in winter. There are some trees considered “bleeders” such as maple, birch and dogwood that should be pruned in mid-summer or late fall. Spring pruning will not injure these plants but there will be a very heavy sap flow at this time.