Pruning your young tree or shrub will make for a stronger, more attractive, lower maintenance plant when mature. Here's some advice on how to do it properly.

Pruning your tree or shrub

Pruning involves the selective removal of parts of a plant, such as branches, buds or roots. Pruning changes the form and growth of a plant, and is a form of preventive maintenance, as many problems can be prevented by pruning correctly during a tree or shrub's formative years.

Main reasons for pruning

1. Improved health. Tree health is improved when branches that rub together, or dead or dying branches injured by disease or animals, are removed.

2. Improved structural strength. Removing defects, such as weak branch attachments or co-dominant stems, makes trees structurally stronger, and thus lowers their potential for failure.

3. Reduced maintenance costs. Pruned trees, which typically have fewer branches than unpruned trees, require less maintenance when mature.

4. Increased tree longevity. Pruned trees serve as functional components of the urban forest for more time than unpruned trees.

5. Improved plant appearance. In landscaping, trees are pruned to control plant size and shape.

6. Protection of people and property. Pruning removes dead or weak branches that could injure people or damage property, as well as branches that obscure vision at intersections.

When to prune

Pruning at the right time is the keystone for success. When to prune will depend to a large extent on the reasons for pruning and the species of tree. Light pruning and the removal of dead wood can be done at any time. For more serious pruning, here are some guidelines. Note that this can vary from species to species.

Winter pruning
This is the most common time to prune. It results in a vigorous burst of new growth in spring. It is usually best to wait until the coldest part of winter has passed.

Spring pruning
At the latest, this must be done well before the buds swell and new leaves begin to develop.

Summer pruning
This should be done soon after seasonal growth is complete, mainly to direct the growth by slowing the branches one does not want, or to slow or "dwarf" the development of a tree or branch. Pruning has a slowing effect because it reduces the total leaf surface, thereby reducing the amount of food manufactured and sent to the roots for their development and the following year's growth of crown.

How much to prune

Generally, no more than 25% of the canopy of a young tree should be removed in any one year (this varies for different tree species). In some cases, removing only 5% to 10% will be sufficient to develop structure and form.

Steps to follow when pruning

  • Prune early in the life of the tree so that pruning wounds are small and  growth goes where one wants it to go.
  • Examine the plant. Each type of plant grows a bit differently; look for what its natural growth tendencies are, and prune to enhance these.
  • Walk around the plant and mentally map out what to remove. This will also determine which tools are needed.
  • Start by removing any dead or damaged growth, and allow plants that are winter-damaged to begin leafing out before pruning. Damaged areas may take several months to leaf out.
  • If a disease is suspected of killing branches, cut back to healthy wood and sterilize your shears with a bleach solution after each cut.
  • Sometimes if branches are crossing, or if two central leaders are developing, you will need to select the best branch or leader and remove the other.
  • Prune out any water sprouts or weak limbs.
  • Thin out old, less vigorous canes to promote new flowering or fruit bearing wood.
  • Pull suckers to assure removal of sucker buds which are present at the base of most shoots. Larger shoots rob the rest of the plant of energy and food.
  • For most shrubs, especially when smaller, head back branches or pinch back terminals to promote a full shape. This can save time in the long run and produce a more pleasing shape that will last without needing major pruning down the road.

REFERENCES

1. http://www.skillins.com/simple-steps-for-pruning/

2. http://tree-pruning.com/how-much-to-prune.html

3. Hagen, Bruce W. (1991). Tree Pruning - Doing it Right, California Department of Forestry

4. Tree City USA Bulletin #1 (2000). National Arbor Day Foundation

5. Training Young Trees for Structure and Form, Supplemental Information (2000). University of California, Agriculture & Natural Resources