Tuesday, April 1, 2014

Have a Safe Pruning Spring

Pruning in Winter

Alexandra Wiens, Prince Edward County Master Gardeners

This past winter has been a very challenging season for gardeners. Many of us have watched helplessly while ice, snow and wind have ravaged and damaged some of our favourite trees and shrubs. When the snow finally retreats this spring there will be plenty of debris on lawns and gardens. Many trees have broken limbs and branches that need to be removed. When bud break finally occurs we will discover how much our ornamental shrubs have died back due to our harsh winter.

It is a great idea to remind ourselves how to prune and what tools to use so that no injuries occur during spring clean-up. Remember an important rule: the branch should fit easily into the jaws of the tool you are using, if it doesn’t, size up. Pruning shears are suitable for making cuts on branches up to 2 cm in diameter. Lopping shears are used when the branch is larger, up to 5 cm, or just out of reach. Pruning saws are best for larger limbs. The blade of the saw can be straight or curved but if you use a bow saw remember there should be no other obstructions within a foot of the branch you are cutting or you risk damaging other limbs on the tree or shrub. If you are using pole pruners to cut material above your head remember to wear head and eye protection.

The three-step cut is important when using a pruning saw to deal with larger limbs. If you have a damaged limb of moderate size (up to 8 cm) you can use the saw to remove it following this procedure. Make a first cut about 15-30 cm from the trunk, cut halfway through the branch. Make a second cut farther outward on the branch. The width between the two cuts should measure about the thickness of the branch. The weight of the limb will cause it to break between the two cuts. Now that the weight is off the limb, make a third cut at the branch collar, close to the trunk of the tree. Always remember that large branches or those at dangerous heights are best left to professionals with the proper equipment.

Most of the pruning we will need to do this spring will be for sanitation purposes, also known as crown cleaning. This will involve the removal of any dead or dying branches. The heavy layer of ice we accumulated during the ice storm that swept through Ontario in December left behind damage that will make trees and shrubs prone to disease this growing season. Sanitation pruning should be done as early as possible to prevent disease. Remember that even evergreens benefit from occasional thinning to allow light into the center of the shrub. This will probably be an excellent year to do that in order to encourage new growth to replace the damage from the ice. Deciduous shrubs with coloured stems can have as much as one third their growth removed per season as the colour is nicest on young stems. So don’t hesitate, particularly if it is a chore that has recently been neglected. Apply fertilizer to all damaged shrubs and trees to encourage new growth after pruning.

This spring will also be an excellent time to step back and inspect all trees and shrubs on the property for future problems that may increase damage next time we have a chaotic weather event. Examine the branches on mature trees. For greatest strength branches should form an angle of between 60-70 degrees with the trunk. Check to see if the limbs have good radial spacing. Is the trunk of the tree sound and disease free? Ask yourself if most of the tree canopy is within 66% of the height from the ground. If you see many branches that form a small angle with the trunk or the tree canopy is too low you may want to do some corrective pruning to prevent future damage from wind or ice.

Evergreen shrubs can be pruned during dormancy and this will result in vigorous spring growth. Whorl branched conifers become denser if the new candles are pinched in half by mid-June. Prune deciduous shrubs according to their growth habit: If they are cane habit, remove dead and damaged canes at ground level. With shrubs that form mounds try to make cuts inside the mound where they will not be visible to remove dead material or gather all the branches into your hand and cut them all just below the gather then release them back into shape. Shrubs that are more upright (tree habit) should have dead stock removed from the center to keep the crown open and maximize light.

Take time this spring to prune any shrubs that may have been neglected last spring. Those that bloom on current season growth like Butterfly Bush, Japanese Beauty Bush, Hills of Snow Hydrangea, Saint John's Wort, Anthony Waterer Spirea, Snowberry, Summersweet, Rose of Sharon and Potentilla will be all the better this year from some early season attention.

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