Between The Shrubs
Before taking shears in hand, it's important to determine what type of plant you have as well as your reason for pruning.
Ask yourself the following questions:
- Is the shrub leggy or sparsely leaved?
- Is it evergreen needles or leaves?
- Is it deciduous spring or fall blooming?
All answers serve to guide what to do when.
Between Two Shrubs
Use nature's cues—one being the appearance of daffodil foliage—as my signal that it is the perfect time to prune and shape evergreens.
Pruning early, before bud break, is especially important for broadleaf evergreens. Early pruning redirects the shrub's energy to produce fresh foliage, which will rapidly cloak newly denuded areas. Late summer and early fall is the least desirable time for any significant pruning, as new foliage is susceptible to winterkill. Deciduous shrubs, typically faster growing, are a bit less finicky about when they are pruned and shaped.
The main consideration in pruning flowering and deciduous shrubs is bloom time. A reliable rule of thumb is to prune immediately after flowering, giving the plant time to set bloom for the next year. I selfishly use this rule as an excuse to cut generous bouquets of azaleas, hydrangeas, roses, and viburnums when those shrubs are in peak bloom. Some of the newer reblooming hydrangeas and azaleas offer more flexibility in when to prune, as they bloom on new wood.
How to prune: Have you seen bare, leggy hedges or foundation plants left with only a veneer of leaves? I'll lay odds that that shrub was regularly and exclusively sheared with a hedge trimmer. Confining cuts to the branch tips stimulates bud break only near the plant's edges and will eventually result in an ever-larger shrub with little interior growth. If a sheared shape is desired for your garden style, a better approach is a combination of pruning and shearing. Reach into the interior of the hedge or shrub, pruning with bypass pruners just above a bud to permit sun and air to reach the interior. Follow up with a shearing (if formal is your style) to neaten the overall shape.
A not-too-painful method of rejuvenating an old, terribly overgrown hedge is called the three-year plan. Each year, for three years, remove up to one-third of the thickest stems down to the base of the plant. This will both stimulate new growth and eventually reduce the overall size. Some rapid-growth shrubs such as acubas, nandinas and mahonias benefit from ongoing rejuvenation to maintain a full robust appearance. Each year, select and prune to the ground the oldest canes.
Renovation pruning is the most aggressive, but sometimes unavoidable technique used to restore hedges or shrubs that were poorly treated in their early shrubhood. When pruning for renovation (again best done before bud break) cleanly cut the entire shrub to within six inches of the ground, while vowing to begin training new growth early and often.
Look closely, and along each stem you'll see tiny nodes called auxiliary buds. They can become future branches, if called upon. A plant's hormones are concentrated at the tips…
Tips for a Faster Job
- Spread a tarp beneath the area to be pruned or sheared to greatly speed clean up.
- Ensure your tools are sharp, disinfected and well oiled.
- Consider where you want new growth to occur, and cut well inside the desired perimeter to allow adequate room for new shoots to grow.
- Aim to have your finished result shaped more like a relaxed A than a right O. Maintaining the shrub with a wider bottom than top encourages photosynthesis (and fuller foliage) all the way to the base of the shrub or hedge.
- After pruning, treat your shrubs to a little well-deserved top dressing of rich compost followed by a moisture conserving mulch.