The plant may become extremely weak, allowing a variety of pathogens and insects to invade. So, although pruning may not kill your plant directly, over pruned trees and shrubs can die as a long-term result of the associated stress.
Since the older leaves aren't getting sunlight they're no use to the plant, so the plant sucks all the valuable nutrients back out of them, which causes them to turn yellow and then brown (it's the same process as with autumn leaves), and then those leaves just fall off.
Rejuvenation pruning is typically done only every three to five years, usually when the shrub starts to look overgrown or stops flowering. Cutting off all the stems and leaves is a huge stressor to the plant so it's best not to do it too often.
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.
After stems have been removed down to the ground, the shrub quickly begins to regrow. Flowering shrubs produce more blossoms in following years and shrubs with colorful stems, such as dogwoods, tend to grow back brighter and more colorful after rejuvenation pruning.
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.
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.
Summer pruning also keeps plants tidy and can allow you to provide better clearance, when necessary. Cutting back plants can also help you direct growth.
Over pruning reduces the foliage needed to make food for the tree, so in effect, it starves it. When a tree has been over pruned, you may not see much new growth during the spring. In the winter, more branches than usual will break as a result of heavy loads.
If you find brown, it's dead (and always will be). Find the uppermost point on a twig or branch where you can find green and cut back to there. New growth should start from these points. Even if your plant has brown bark all the way to the ground doesn't guarantee it's dead.
There are several reasons for shrubs to have brown leaves and dead branches. These include: Extreme temperatures: A sudden cold spell can shock the leaves into turning brown. We commonly call this winter burn or winter damage, but it can also happen during a heat wave.
If your shrubs are struggling, but not completely dead, you can give some older shrubs new life with pruning. How to know if this is worth the time and effort? Look at the core of the shrub. If it's more brown branches than green foliage, cutting it back will look pretty ugly.
For some shrubs (azaleas, abelias, hollies and others), a hard renovation pruning will allow the entire shrub to regrow evenly. In other shrubs, including many (but not all) needled evergreens, the loss of a section is never fully recovered because of the way they grow.
Pruning helps to encourage new growth and keep the hedge looking full and healthy. Additionally, it helps to remove any dead or dying leaves or branches, which can help to prevent the spread of disease. Finally, pruning can also help to shape the hedge and keep it looking tidy.
Plants that have had too much sun suffer from leaf scorch, a condition where the plant can't keep up with its hydration needs and the outer leaves dry out and are burned by the sun. Leaf scorch can also be caused by bacterial infections or by nutrient deficiencies.
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.
When pruning mature, overgrown shrubs, remove the thickest branches first. Cut them back to the base of the shrub to promote new growth. Hand pruners are useful for smaller branches. Some can handle diameters up to an inch, but long-handled loppers give you leverage to cut branches 1 to 2 inches in diameter.
Pruning Trees in Summer: Cut Conservatively
If you prune to excess in summer, next year, your trees may not be as full. Summer pruning takes away from the tree's total number of leaves, and fewer leaves mean less food flowing throughout the tree for next year's growth.
Note: Plants should be well watered in the days ahead of pruning. Those that are experiencing drought stress should not be pruned. Pairing a deep soak and fertilizing with your pruning will enhance the lush result.
During seasons of drought, it may be beneficial to lightly prune back plants so that they will have less need for water. Use your best judgement on which plants may need to be pruned based on the symptoms of lacking water.
So, how hot IS too hot for plants? The general answer is around 90 degrees F, with some exceptions to the rule. This means that when temps rise above 90 and remain there for a lengthy spell: Leaves wilt.
As a general rule, a light summer pruning can be performed on most deciduous trees and shrubs. Heavier pruning should be performed when the tree is dormant, preferably in late winter before active growth begins.
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. This is the sweet spot for pruning and will help keep everything looking and performing its best.
Ideally, hedges should be pruned in late winter, when plants are dormant and haven't produced buds—particularly if you're cutting back drastically. “You don't want them to break bud before you prune because you want the plant's energy to go toward producing new growth where you want it,” says Roger.