Gardening Help FAQs

Here are answers to some of the most common questions we receive about garden plants. You will find concise information on general gardening techniques as well as plant selection and care. For detailed information on specific plant pests and problems refer to our Common Garden Pests and Problems page.

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Horticulture Questions and Answers

How do I prune a tree?

Trees are valuable landscape plants. Care for them properly and your trees will live a long and healthy life.

Good pruning keeps your trees attractive, healthy and less susceptible to injury from natural forces such as strong winds and ice. On the other hand, poor pruning practices, "topping" in particular, destroys the natural look of a tree and makes it more prone to pests and weather problems. It ultimately shortens the tree's life span. Medium and large-scale trees should be pruned by an arborist or a trained tree service professional. Professional tree work will cost more, but view it is as an investment. If you don't have the knowledge or the equipment to properly prune larger trees, you may injure yourself; or damage the tree, nearby buildings, utility wires or other landscape plants while pruning. These pruning jobs are best left to professionals. Arborists are listed in the yellow pages under "tree service". For more information on hiring an arborist, read the message "How to Select a Tree Service".

If you want to prune smaller trees, here are a few helpful tips. Use the right tools. You can prune most shrubs and small trees with a hand pruning shears, a lopping shears, and a hand pruning saw. Although you should do most pruning from late winter through spring, other times of the year are also acceptable for most trees. Some trees, however, will bleed if they are pruned in early spring. Examples include maples, dogwood and birch. This heavy sap flow bleeding will not hurt the tree, but you can prevent it by pruning during the growing season.

Pruning wounds are best left unpainted. Pruning paint does not stop bleeding or prevent decay and in some cases may even increase decay. Tree wound dressings are not recommended for most general maintenance pruning cuts, including those made on trees more prone to bleed.

When pruning trees, there are several types of branches to remove. Prune out dead branches wherever they occur. Remove broken or diseased branches. Remove those branches that are rubbing together or growing back toward the tree's center. Finally, prune out water sprouts and suckers. Water sprouts and suckers frequently occur on flowering crabs, hawthorns, lindens, magnolias, dogwoods and other trees. Suckers are long straight shoots that grow out of the ground from the tree's roots. Water sprouts are long straight shoots that grow off the trunk and main branches. It is also important to remove all but the strongest central leader early in the life of a tree which is prone to developing multiple leaders.

Occasionally you may need to remove lower branches on mature trees. You can usually do this any time of the year. Because these branches are usually large it's best to use the three-cut pruning method for removal. To do this, make an undercut halfway through the branch, a foot from the main trunk. Then make a second cut from the top, a few inches beyond the under cut. This second cut should remove the branch, causing it to drop straight down without ripping the bark, which might have occurred if you hadn't made the first under-cut. Remove the branch stub which remains, with the third and final cut. No matter what kind of branch you're pruning, the cardinal rule of pruning is to never leave a stub. Make your final pruning cut flush with the branch collar when the collar is evident. The branch collar appears as the natural swelling or bark bold which occurs where the branch joins a larger branch or the trunk. Do not cut into this collar. Stay just to the outside, leaving no more than a one-half inch stub. Also, do not cut into the main trunk. Doing so will create a larger wound and delay healing.