Are you completely confused about pruning your plants? There are many excellent pruning manuals available complete with details and diagrams, but it seems so complicated that many gardeners are afraid to tackle this chore. There are several principles to understand that make the task much simpler and much less intimidating. Once you understand these basics, you will be able to follow the instruction manuals with confidence.
Before you prune you should have a clear idea of why you want to prune. Then you can choose the proper technique and the best time of the year. Pruning can be used to control the size, increase or decrease the density, maximize flowering, create special shapes, improve the health, remove a hazard, and improve light and air penetration, as well as many other reasons. Determine the goal you are trying to achieve so you can choose the correct technique and the best time to prune.
Here are a couple of simple rules to remember. They apply to all pruning jobs no matter what kind of plant or time of the year.
The Three D's Rule says you can prune anytime for the following reasons: Damaged - Diseased - Dead. You can prune to remove the 3 D's anytime. (If you are removing a fungal disease avoid pruning during the time the fungus is sporating as that could allow spores to infect new cuts). But otherwise it is safe to cut out damaged branches, diseased branches, and dead or dying branches any time of the year.
You can do light pruning anytime. For example if you want to remove a stray branch, you don't have to worry about timing. Just cut it off.
Timing & Technique
That was easy. Let's get a little more specific. In situations other than those above, you will need to consider the type of plant you are pruning in addition to the goal you are trying to accomplish. There are different techniques and times to prune depending on the type of plant. Here is a general summary for common types of landscape plants.
Do not prune in spring or fall when the sap is running. Summer or winter pruning are both acceptable and both seasons have their own advantages.
Technique: Never cut off the end of a branch that is over 3-inch diameter. Not only is this ugly and looks unnatural, but it will cause the growth of 'watersprouts' near the cut end. The dense growth of watersprouts cuts off light to the inner area of the tree. Instead prune the branch back to a fork.
When you remove a branch or cut back to a fork, leave the collar (thick area at the base of a branch where it attaches to the trunk or another branch). This practice results in less cut area exposed and also leaves the cambium tissue that is contained in the collar to grow over the wound.
You can trim branches less than 3-inch diameter using selective pruning. Select a bud (swelling on the side of the branch where a sprout will emerge) and cut just above it, keeping close to the bud. Don't leave a stub. The bark cannot heal over the stub and your tree will be susceptible to disease and rot. Make a clean cut at a slightly upward angle. This will allow the wound to heal quickly, and the slant prevents water (which can cause rot and disease) from soaking into the wound. The proper tool for this pruning cut is the hand pruners, long handled loppers, or a pruning saw for the larger branches.
Conifers - random branching type of conifers
(These don't have clustered needles, e.g., yellow cedars, hemlock, junipers)
Spring or summer is the ideal time to prune if you want to control the size or increase the density of plants such as in a hedge. This is the only time you can use a hedge trimmer tool. Never use hedge trimmers on any type of plant unless you want them to look like a hedge.
If your goal is to retain the natural look while keeping the tree or shrub small, it is important to use a different technique and a different tool. Use your pruners or loppers to cut back at a fork in the branch instead of the tip. Stagger your cuts. Don't cut back all the branches to the same length. You may also cut back the leader to shorten it. You can do this pruning any time of the year.
Conifers - whorled type
(have clustered needles, e.g., pines and firs)
This type of conifer produces new growth called 'candles' at the end of the branches. You can control the size by snapping off all or part of each candle with your hand. To reduce the size and increase the density of the plant, remove the whole candle. To reduce the size of the plant without increasing the density, remove just part of the candle. The production of candles varies by species but occurs in the spring or early summer. Do not use this technique after July 4, as this could cause contorted growth.
If you just want to thin the growth, you can remove branches using your pruners or loppers by cutting the branch back to a fork. This can be done at any time of the year. I usually do it in December so I can use the branches for holiday decorating.
Flowering or fruiting shrubs - deciduous or broadleaf evergreens
Flowering or fruiting shrubs can be pruned according to whether they flower in spring or summer. Usually the goal is to control the size of the shrub and encourage flowers and/or fruit. So the timing is fairly simple. Don't cut off the branches until after they have flowered or set fruit.
For spring flowering shrubs that time would be in the spring or early summer as soon as possible after the flowers have faded. The new growth that is produced after the pruning will flower next spring.
For summer flowering or fruiting shrubs, you may want to enjoy the fruit, decorative seeds or branching pattern during late fall or winter. So you can wait to prune them until late winter or early spring. Being cut back completely to about 1 ft tall can rejuvenate some species. But if you don't want to create a hole in your landscape, you might prefer to shape up the top and remove just the older stems and trunks leaving some of the younger trunks. Next summer's flowers will appear on the new spring growth.
Keep in mind that for deciduous shrubs you should avoid pruning while the sap is flowing - spring or fall. The healing process is slow in the late fall when the plants are preparing to become dormant. Late fall is never a good time to prune any plant because pruning tends to promote new growth that will not have time to develop a thick cuticle to protect it from freezing. Generally it is advisable to avoid significant pruning within 6 weeks of frost.
There are many specialty techniques for special species or special effects. But whether you are pruning grapes or roses or Christmas trees, the techniques will all be based on these principles. Be sure to start with a clear idea of what you want to accomplish, then proceed according to these guidelines. This will make understanding the pruning manuals much easier.
About the Author Sherry Palmer studied horticulture at South Puget Sound Community College and established a small organic farm, Creekside Gardens, on the land where her parents and grandparents once farmed. In addition to the organic landscape nursery, she also raises red wiggler worms and promotes recycling of kitchen wastes using a home worm bin. All of her products are marketed online at her web site www.wormlady.com which she designed and maintains herself. This site provides lots of free how-to advice on vermiculture and links to many other gardening resources. She is employed as a business manager in the local area and also offers landscape design services.