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

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How do I prune an ornamental tree?

To many gardeners the art of pruning trees is mysterious and misunderstood. However, next to watering, pruning may very well be one of the most important plant maintenance tasks.

Pruning is the removal of part of a plant, live or dead, for the benefit of the whole plant. Proper tools are essential. The best tools are a sturdy pair of bypass pruners and a saw that cuts when pulled. Proper pruning tools will prevent torn or ragged cuts. Torn cuts will not heal properly and will leave an area exposed for decay.

Good pruning cuts should be made just forward of the branch bark ridge, found between the tree trunk and the point at which the branch originates from the trunk. Stubs left by improper pruning cuts will eventually rot and spread rot to the main tree trunk.

When pruning a tree, the first priority is to remove diseased, dying or dead parts. This initial step is important in preventing disease from spreading and infecting healthy branches.

Many flowering trees produce two types of vigorous shoots from latent buds. Latent buds that develop on the trunk or lateral branches are called water sprouts. These can quickly overpower a tree and rob it of valuable nutrients. Water sprouts can be identified by their vertical growth habit and should be removed at the point of origin. Suckers, latent buds that develop from the roots, are also detrimental to the health and vigor of the tree. These should be removed at or below ground level.

Trees that have not been pruned on a regular basis will often develop branches that compete or rub against each other. These must be removed to prevent other branches from being damaged and ultimately dying back.

Trees that have not been properly pruned often develop weak or narrow crotches. The crotch of the tree is any place where two branches come together. A wide crotch, about a 30-70 degree angle, should be promoted if at all possible. A weak crotch can result in severe damage during high winds.

Selective removal of branches in a mature tree's crown will allow for greater air and light penetration. Many insects and diseases thrive in a stagnant air environment. By improving air circulation through a plant's crown, many of these problems can be prevented without spraying. If, however, insects and diseases do become a problem, a more open crown will allow for greater spray penetration. Air and light penetration are important factors in a tree's flower and fruit development. Without adequate air and light the flowering and fruit production will be greatly diminished.

Correct pruning is important in maintaining a plant's size and form. Thinning will reduce a tree's density, but will not affect its overall size. Without reduction pruning, a plant will quickly grow out of proportion to the surrounding landscape. It is important to be familiar with a tree's natural form so that its appropriate shape can be maintained.

Prune your tree in the winter if you want to develop the tree's structure, but be careful not to overprune during this dormant period. Overpruning will result in an excess of new spring growth. Prune in the summer to inhibit growth; summer is a good time to control a plant's shape and size.

Pruning is an art and a science that requires practice and years of observing plant reaction to pruning. Patience is critical. It is always better to remove too little than it is to remove too much. These pruning guidelines will not only produce a well shaped tree, but one that will remain healthy and vigorous for many years of enjoyment.