Spring cleaning doesn’t have to apply to just your home and office. It can also apply to trees and shrubs. For arborists, “cleaning” means to prune out dead, dying, diseased and broken branches from a tree or shrub. Although cleaning can be done any time of the year, spring is an excellent time, just before the plant puts out a new flush of growth.

“The best time to prune live branches may depend on the desired results. Growth is maximized and defects are easier to see on deciduous trees if live-branch pruning is done just before growth resumes in early spring,” according to an article published by the University of Florida’s Environmental Horticulture program.

“Pruning when trees are dormant can minimize the risk of pest problems associated with wounding and allows trees to take advantage of the full growing season to begin closing and compartmentalizing wounds,” the article says. “A few tree pathogens, such as the oak wilt fungus, may be spread if pruning wounds are made when the pathogen vectors are active.”

Pruning strategies

If your goal is to maximize flowering on spring-blooming trees, prune just after the tree or shrub has finished flowering — this avoids cutting off the flower buds for next year.

The general rule of thumb to prune just after flowering can also be applied to plants that flower later in the season.

Most routine pruning to remove weak, diseased or dead limbs can be accomplished at any time during the year with little effect on the tree. Some trees, such as maples and birches, tend to “bleed” if pruned early in the spring. This may be unsightly, but is of little consequence. When you’re pruning this spring, here are six tips:

  • In blossoming basics, timing is everything. To maximize flowering on spring-blooming trees, prune just after the tree or shrub has finished flowering. Pruning at this time avoids cutting off the flower buds for next year.
  • Less is more when pruning a newly-planted tree. Limit pruning at the time of planting to removal of damaged branches. The tree will develop a stronger root system if it has a fuller crown.
  • Don’t flush. Cutting branches flush with the trunk removes the important branch collar, which helps the tree to close the wound. Cut just outside the branch collar at the base of the branch.
  • Put away the paints. There’s no need to apply wound dressings. Research has shown that the common wound dressings do not inhibit decay and do not bring about faster wound closure. In fact, many of the commonly used dressings slow wound closure.
  • Topless trees are indecent. Don’t top trees. Topping trees can make them prone to failure down the road. Topping leads to decay and weakly attached branches. Besides, topping makes trees ugly.
  • No tourniquets required. While some trees, such as maples and birches, will “bleed” or lose sap from pruning cuts made early in the spring, this bleeding does not hurt the tree. But because bleeding is unsightly, you might want to prune these species during the dormant season.

Also consider these recommended general pruning practices:

  • A few tree diseases, such as oak wilt, can be spread when pruning wounds allow spores access into the tree. Susceptible trees should not be pruned during active transmission periods.
  • Heavy pruning just after the spring growth flush should be avoided. This is when trees have just expended a great deal of energy to produce foliage and early shoot growth. Removal of a large percentage of foliage at this time can stress the tree.
  • Use professional tools. Not only will they last longer and make better cuts, high-quality, sharp tools are safer. Saving $10 or $20 on a hand saw may seem tempting, but how many will you go through making hundreds of cuts a day? How long will a less expensive tool stay sharp? Sharp tools cut better and more efficiently, saving time, money and effort. Sharp tools also leave behind crisp edges and smooth surfaces.
  • Knowledge of growth habits, species, environment, likely pathogens, pruning interval, timing and many other factors will help you determine the amount of pruning suitable to the job at hand.
  • Pruning of newly-planted trees should be limited to corrective pruning and removing torn or broken branches. Save other pruning measures for the second or third year.
  • The belief that trees should be pruned when planted to compensate for root loss can be misguided. Trees need their leaves and shoot tips to provide food and the substances that stimulate new root production. Unpruned trees establish faster, with a stronger root system, than trees pruned at the time of planting.
  • All arborists should own a copy of the American National Standards Institute A300 Standards “Part 1: Pruning.” This is the national pruning standard of practice and for writing pruning specifications. It can be purchased from the Tree Care Industry Association online at TCIA.org. Another recommended guide is the International Society of Arboriculture’s “Best Management Practices: Pruning.” This BMP (and the ANSI A300 Standard) can both be purchased online from the International Society of Arboriculture online at ISA-Arbor.com.

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Editor’s note: Portions of the following were originally published in the May 2013 issue of Tree Services, from the article titled “Spring Cleaning for Trees and Shrubs,” written by Sharon Lilly, former International Society of Arboriculture director of educational goods and services.