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Wednesday, June 19, 2024
Growing Together: Pruning evergreens, the smart way
Natural pruning of evergreens is done using secateurs or loppers to make selective cuts to thin or reduce the size of a plant, while keeping its natural form. JOANNE YOUNG

Pruning plants properly seems to be one the most frustrating and misunderstood areas of gardening.

The longevity of a plant is partially determined by how well a plant has been pruned over the years.

Most evergreens need pruning to stay within the size and scale of most landscapes.

Evergreens come in all different shapes and sizes: spreading, rounded, upright, horizontal, and weeping.

The natural branching pattern of the plant dictates its shape. By respecting this inherent form when pruning, it is possible to limit the size of the plant without changing its form.

Not only does this preserve the plant’s true beauty, but it saves the expense of replacing overgrown plants.

Now is a great time to prune your evergreens.

Facts about evergreens:

  • Because the evergreen retain its foliage year around, it compensates for this by losing its oldest growth every year. An evergreen plant will usually hang on to its needles or leaves for three to five seasons.  
  • Unlike deciduous trees and shrubs, most evergreens will not rejuvenate itself if cut back to old, bare wood. Yews are the main exception.
  • Most evergreens grow primarily from buds set the previous year and have few, if any, latent buds. It is generally safe to prune back only to one- or two-year-old growth, which still has existing buds.  
  • It is almost impossible to rejuvenate an old, overgrown evergreen. Therefore, it is important to prune on a yearly basis and not wait until the shrub or tree has become to large. 
  • The best time to prune most evergreens is after the new growth has emerged late spring to early summer. On most evergreens, the new growth emerges a lighter colour. Once the colour has faded to the older growth, this would be the best time to shear.
  • To keep a more natural look, make individual cuts with the secateurs and not with the shears.
  • To achieve a more formal, sheared, geometric look, shear up to three-fourths of the newest growth.
  • Most evergreens will push out new growth twice in a season: late spring and again in late summer. You could do a second pruning at this latter time but not too late into the fall because it will stimulate new growth that will not have time to harden off before winter.
  • Always make sure that your pruners are sharp or it may cause a brown cast.

When pruning any plant, it is always good to know what your goal is and that will help you determine how to best prune your shrub.

Here are the two main goals of pruning evergreens:

  1. Control the size of plant

The best way to control the size of a plant is by natural pruning. Natural pruning means that you are making selective cuts in order to thin or reduce the overall size of the plant. 

This cannot be done with shears, but with secateurs or loppers. This means cutting one stem at a time and not just shearing off the tips. 

When pruning is completed, it should look like no cuts have been made and should still have its natural form.

  1. Maintain a certain shape

One of the goals of pruning might be to maintain a certain shape such as a hedge, a pyramidal evergreen, a globe form, or specimen plants like spirals and pompons. 

This is best achieved by shearing. 

With shearing, you are just removing new tip growth, creating a full dense look. 

Even though electric shears makes the job easier, hand shears make a much nicer job of things. 

Electric shears just tear the plant tissue, while hand shears makes a cleaner cut. 

When the plant tissue is torn there is more die back at the tips giving the sheared shrub a brownish tinge. 

Always make sure that any pruning tool is sharp and clean before using to prevent this from happening.

Do not top evergreens!

An unsatisfactory approach to tree maintenance for any tree is to top it. 

Topping is the removal of all branches of a mature tree above an arbitrary height. 

Large evergreen trees do not respond well to topping. 

The removal of the upper main trunk through topping opens to tree to internal decay, disease or damaging insects — it also removes the most productive portion of the crown of the tree. 

The result is that the tree becomes a hazard to itself, neighbouring trees and your property. 

The practice of topping to control tree size of growth is not justified. 

If the tree is too large to fit the space, it should be removed and replaced with a smaller species.

Happy pruning.

Joanne Young is a Niagara-on-the-Lake garden expert and coach. See her website at joanneyoung.ca

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