After “how?", the second most-asked question we get about pruning is “when?” (Or, "Can I prune this now?") The rule of thumb is to prune immediately after bloom for flowering shrubs, in late winter or early spring for non-blooming shrubs (particularly for heavy pruning), and not after mid-August for any shrubs.
Pruning can make plants hardier and help them over the winter too. Other plants, however, can't handle fall pruning—such as azalea, viburnum, Loropetalum, and lilac. If you prune a spring-blooming tree or shrub after its flower buds have formed, you'll be lopping away any opportunity for a spring showing.
DON'T prune during fall.
No matter what type of shrub you have, fall pruning can stimulate late-season growth that may not have enough time to harden. This can weaken and damage the plant—especially if there's an early frost. Instead, wait until winter and trim bushes when the plant is in deep dormancy.
No Flush Cuts
While it may look clean and streamlined, a flush cut removes the branch collar, an area of tissue that's needed to form a seal over the pruning cut. Because the plant cannot close over the wound, a flush cut leaves an opening for pests and pathogens to enter the plant and damage or kill it.
What is improper pruning? Cutting too close to the nodes or too far from the trunk is referred to as improper pruning. It can cause irreversible damage to your plants. What types of pruning are often done? Thinning cuts, reduction cuts, and heading cuts are often done to prune a plant.
Winter is usually the best time.
Dormant pruning is usually done in late winter, six to 10 weeks before the average last frost in your area. You can prune shrubs at any time of year if it's necessary—for example, to remove broken branches or dead or diseased wood, or to remove growth that is obstructing a walkway.
Don't Prune in Late Summer and Fall
Pruning shrubs in August or early September may encourage a late flush of growth. This new growth may not harden sufficiently before the arrival of cold weather and be susceptible to winter injury.
Summer flowering shrubs should be pruned in late winter or early spring. This still gives them time to set flowers for the following year. Deciduous shrubs that aren't grown for flowers can be trimmed back at the same time.
Mild fall weather may have you thinking about pruning shrubs and trees. But it's better to wait till late winter, or, at least, after leaves have fallen. Fall isn't the right time to prune trees and shrubs. There are good reasons to wait till late winter or after the plants' leaves have fallen.
Pruning evergreen bushes is best done in late March or early April before new growth begins. Light pruning can also happen in late June or early July. Avoid pruning evergreen shrubs in the fall, since they are more susceptible to winter injury.
Follow these tips to prune your bush without killing it: Prune in the late winter or early spring before new growth begins. Cut back no more than one-third of the total length of each branch. Ensure all cuts are clean and sharp, angling them slightly away from the bush's centre.
Late summer or early fall pruning causes vigorous re-growth of tissue, which in some cases may not harden off by the time winter arrives, leading to possible cold damage to the new growth.
You should not do aggressive pruning in summer. Major structural pruning should wait until the plant is dormant in winter. Improper pruning will stress the plant. You might cut off valuable buds.
According to gardening expert Mike McGrath, author of Mike McGrath's Book of Compost, and radio host of the show You Bet Your Garden, the rule of pruning is that you should NOT prune in fall. That's right, nothing and no exceptions.
Pruning services often recommend pruning roses in the late summer, since rosebushes can usually produce one more round of flowers before temperatures drop in late October. Remove dead canes, crossing canes and suckers. For canes that you want to blossom this fall, cut back to groups of five leaves.
The period between the full and new moon (third and fourth quarters) is best for harvesting, slowing growth, etc.
You probably already know just how fast shrubs grow and start to look messy. If you wait too long, your shrubs will start to become an eyesore. Pruning less of the plant but more frequently is by far the best for the overall health of it. We recommend every other month, which comes out to be five times per year.
Proper pruning can renew or rejuvenate overgrown, deciduous shrubs. One method is to prune them back over a 3-year period. Begin by removing one-third of the large, old stems at ground level in late winter/early spring (March or early April).
The 1/3 rule involves cutting about 1/3 of wood during any pruning activity. This moderate pruning practice is a balanced approach to thinning out shrubs to stimulate new growth. The plant loses a good amount of stems, usually on the top section, allowing more light and air to enter the inside of the plant.
Pruning at the wrong time can send a plant into shock, stunt its growth, or cause it not to bloom that season. It can take years for a plant to recover, if it can. Heavy pruning is best done when a plant is dormant. For most trees, that's winter.
Damage caused by pruning
When improperly performed, pruning can harm the tree's health, stability, and appearance. Several consequences occur when pruning is not performed at all. These include development of low aggressive limbs, weak codominant stems, bark inclusions, and accumulation of dead branches.