Pruning Young Trees

In my opinion, the most complete, up-to-date and authoritative pruning sites are:

http://hort.ifas.ufl.edu/woody/pruning/ This site by professor Ed Gilman of the University of Florida Environmental Horticulture Department is a practical complilation of Gilman's research and that of others who study trees, tree structure, wind effects and tree stability.

http://www.treesaregood.com/pressrelease/press/PruningPR.aspx

Basic Pruning Concepts for Young Trees

  • Less pruning is almost always better for the tree's health than more pruning. Don't let a tree service make you feel like you are getting your money's worth by removing more limbs and foliage. Less pruning is better. Here's why...
    • Green leaves are the factories that make food in the form of carbohydrates for the tree. Remove too many leaves and the tree is weakened.
    • Carbohydrates manufactured by the leaves is stored in woody tissue in the branches and trunk. When branches are removed, stored carbohydrates are lost and the tree has to make more.
    • Excessive pruning causes a tree to form water sprouts sometimes called suckers. Water sprouts are often seen as clusters of small twigs and branches that sprout from a pruning cut stub or from the interior portion of larger branches. Sprouts are a way the tree is putting out more leaves as quickly as it can to make more carbohydrates. Unkowleadgeable tree services will offer to come back for a fee to "clean up" those ugly sprouts, which the tree service caused in the first place by excessive pruning.
  • Young trees should be pruned for structural strength, not esthetics, by eliminating double or triple leaders that will form a weak structure as the tree develops over the years.
  • Small, young trees can tolerate more pruning (up to 33%) than older, mature trees, which should not be pruned more than 10% to 20%. Old veteran trees should be pruned even less.

Common homeowner pruning questions

Q A tree fell on a holly. It broke in half. How should I handle it? The holly is two year’s old and has grown about 3 ft. last year.

A First try to make a clean cut that will callus over better than the ragged broken edge (wound) you now have. Make the cut below the break and just above and next to a side branch or bud. Don’t use pruning paint because research has shown that pruning paint does not help healing and may provide a moist dark environment where decay fungi can thrive. During the summer as the new growth emerges, you can do some structural pruning to maintain a single central leader with alternating side branches.

Q. I have purchased a live oak tree. I was told by someone to cut the top outof the tree to make it bushy. Another person told me that was wrong. What should I do?

A. Topping or cutting out the top growth of a tree is seldom justified and usually creates an unnatural growth form with many side branches coming out of the same area of the trunk. This type of pruning is still done even by self -taught experts but is considered by arborists and other people who deal with tree problems to be a very bad practice. Topping leads to weak branches and a hazardous tree when it is older. A hazardous tree is a large, mature tree that has narrow crotches and double or triple leaders (trunks) that will split and fall during storms.

When purchasing a young tree, try to select a tree with a single, central leader (stem or trunk) with evenly spaced side branches much like a Christmas tree shape. Notice the drawing of the good tree structure and the poor tree structure.

Q My husband is pacing the floor with the pruning shears in his hand. He wants to go out and prune back the plants that died in the freeze. He says they look ugly. I tell him not to do it yet. Who is right?

A I love getting in the middle of these domestic disputes. You are correct. Hold off on the pruning until new growth comes out when warmer weather arrives. That way you will know exactly how far back to cut. Also, the dead, ugly material provides some protection from additional freezes that still may occur.