Cedar Trees


We have 5 Cedar Trees, they have not been pruned for 15-25 years and have suffered from a lack of water for many years as they are located right next to a Locust Tree and the cement staircase of an adjacent property. Last few years they have been well fertilized and had deep root fertilizing. They suffered from small scales a few years ago.
We live in Rosedale Toronto and have Clay soil but have added pebbles and compost to the soil.
One can clearly see the trunks through the foliage, they were not visible a few years ago. Our Questions (1) Do the Cedars look too thin and spindly to stand up to a light pruning in the hope of encouraging the cedars to thicken up? (2)Could this safely be done with electric tools or are we better to do this by hand? (3) How much should we remove (4) When is the best time to do this? Photos follow by EMail


There are ideal times and methods for pruning all types of shrubs and trees and in your case, the Cedars are best pruned in late winter to early spring before any new growth.  That being said, giving them a very light trim to keep a shape can be done anytime.  Ideally, pruning the hedge really involves giving it a light shearing being very careful not to cut back to the main or bare branching as this old wood rarely regrows.  Use a clean, sharp hedge shear or clippers and remove up to a third of the needles and no more.  In my experience, using hand tools rather than power tools is best as it is very easy to get carried away and over prune with the latter.  During this exercise, you could also remove any dead or damaged branches.

For more information on cedars and pruning read this super blog from Mark Cullen: https://mark-cullen.blogspot.ca/2010/09/cedar-hedges-investment-that-grows.html

Also, here are two great reference books on pruning that you may be interested in having a look at:

  • Pruning Made Easy: A gardener’s visual guide to when and how to prune everything, from flowers to trees  by Lewis Hill
  • The Pruner’s Bible: A Step-by-Step Guide to Pruning Every Plant in Your Garden by Steve Bradley

Cedars naturally grow in wet ground so regular watering is a must, especially in hot drought conditions.  Watering must be deep so a light sprinkling on the top of the soil is of no use.  Watering should begin as soon as it is safe to get your garden hose out or sprinkler system opened up in the spring, and should continue right until freeze up in the late fall.  Mulching is important to hold that water in the root zone, deter weeds and shade the roots – this can be wood chips or bark.

Feeding regularly is important as well.  A fertilizer that can be dissolved in water and applied directly to the root area will allow more of the nutrients to reach them.  Topdressing with sheep manure compost, worm castings or regular compost (before applying the mulch) will not only feed the hedge but will also improve soil structure and encourage beneficial microorganisms.

If you find that your cedar hedge bare spots become unsightly, consider planting some perennials in the spaces which would not only fill the gaps but would give you some foliage contrast and blooms.

Hope this helps.