Prune any other stems to shorten or shape the shrub. Use hand pruners or loppers for this job, not hedge shears. Shrubs to prune in early summer: lilac, azalea, forsythia, Japanese kerria, weigela, deutzia, mockorange, St. John's wort, viburnums and the colorful redtwig and yellowtwig dogwoods.
Similarly, avoid trimming summer flowering shrubs before they have flowered and wait to do so until after they have finished flowering. Non-flowering shrubs can be trimmed at any point in the summer to shape them or to reduce their size, but remember that regrowth will be slow during hot, dry, and stressful conditions.
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.
Prune all evergreens, except pine, before new growth starts in the spring or during the semidormant period in mid-summer. When pruning, follow the general branching pattern to maintain the natural shape. Remove dead, diseased, or broken branches anytime.
Midsummer can be an excellent time for pruning flowering shrubs as long as you prune the right plants at the right time. In general, you cannot go wrong if you turn your attention to plants that have bloomed recently. Prune off everblooming roses after their first flush of bloom to encourage further flowers.
Perennials to prune in early summer: joe-pye weed (Eutrochium), tall coneflower (Rudbeckia 'Herbstonne'), bee balm (Monarda), catmint (Nepeta), yarrow (Achillea), balloon flower (Platycodon), Culver's root (Veronicastrum), Veronica and garden phlox (Phlox paniculata).
August is an excellent month for pruning many shrubs and trees in the landscape, just ahead of the fall growth spurt. It's also a perfect time for pruning backyard fruit trees for size control. Removing excess growth now instead of waiting until January will help keep fruit trees smaller.
Pruning mid-summer will work as well, but avoid pruning evergreen shrubs in the fall, as this could leave them susceptible to winter damage. Approaching pruning for different evergreen shrubs should vary, depending on the type of shrub.
Late spring is an excellent time to prune evergreen shrubs in the landscape. Pruning just after the emergence of the spring growth will provide a basis for helping to shape the plant while retaining the natural look.
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.
Common Mistakes
Prune just above a healthy bud, with the bud pointing in the direction you want the plant to grow. Cut at a 45-degree angle, with the low point of the cut opposite the bud. Don't cut too far from or too close to the bud you want to encourage. Leave a “collar” when cutting off a branch.
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.
Boxwoods can be pruned any time but late summer and early fall.
Few plants are pruned this time of year because pruning encourages new growth that does not have time to harden off before winter. Late-season pruning typically does more harm than good.
Helps Control Disease
Some trees, like oaks, should only be pruned during the dormant season because they are especially susceptible to oak wilt disease, which is known to spread extremely fast in the spring and summer.
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.
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.
Prune evergreen shrubs, such as juniper and yew, in late March or early April before new growth begins. Light pruning may also be done in mid-summer. Avoid pruning evergreen shrubs in the fall. Fall-pruned evergreens are more susceptible to winter injury.
Boxwood shrubs pruned between late summer and fall will leave them susceptible to frost damage, especially if there's an early frost. Wait to prune your boxwood until after April 15, the average last spring frost date for St.
The period between the full and new moon (third and fourth quarters) is best for harvesting, slowing growth, etc.
If the shrub is thin or lanky, encourage new growth by trimming individual branches back by no more than one-quarter their length. Cut just above a node, which looks like a small bump on the stem where new growth will appear.
The best season to prune trees is while they are dormant, or generally between November and March. This means waiting for them to lose their foliage and cease growth, but before forming buds. For fruit trees such as the apple tree, prune in late winter.
Pruning and training
Prune wisteria and climbing shrubs such as Pyracantha after flowering. Hebes and lavenders can be given a light prune after flowering. Rambling roses can be pruned now, once they have finished flowering. Give hedges a final trim over now.
Any gardening expert will tell you, (contrary to what you may believe) that pruning encourages new growth just when the plant is trying to go dormant and new growth doesn't have enough time to harden before the first frost and freezing temperatures hit. Pruning at this time of year will severely weaken the plants.