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Ensure a healthy cedar hedge

How to maintain a cedar hedge - watering, fertilization, winter protection and pruning. Undemanding, cedar trees are fairly resistant to diseases and insects

If finding enough time for garden maintenance is a problem, a cedar hedge might be your answer. Cedars are gorgeous and undemanding, rustic and fairly disease-resistant: cedars will provide you with the privacy you need to enjoy your backyard without demanding too much time in maintenance.


A cedar hedge does not require much care. Planted in rich, well-drained soil and in full sun, cedars can live 60 to 80 years.


Cedars are able to tolerate a week without rain. If after 5-7 days rain is still not in the weather forecast, give your hedge a thorough watering so that moisture penetrates right down to the roots.

For optimum watering:

  • Install a soaker hose on top of the soil directly over the root balls of your hedge.
  • Water for one hour, once per week.
  • Watering in the evening and out of the sun is preferable so you don't scorch the foliage, and always water long enough for the water to penetrate (short watering periods will only dampen the surface of the soil).


Since you added phosphorous-rich fertilizer when you planted your hedge, there is no need to fertilize any more during the first year.

After the first year:

  • Choose a fertilizer rich in nitrogen. BOTANIX fertilizer deciduous trees, conifers and hedges 15-5-15 is designed specifically for trees and shrubs.
  • Add fertilizer at the beginning of May in an even layer, extending one foot on either side of the hedge, then again at the beginning of June and once more at the beginning of July.
  • Never apply fertilizer after mid-July so that the trees have enough time to prepare for winter.

The most common insects

Insect attacks constitute the most common cause of disease in cedars.


What are they? - Small nocturnal moths which lay their eggs in July and August in cedar hedges. Larvae over-winter in leaflets, and when they awake in the spring, they feed on the foliage. Damaged leaflets will change colour, yellowing first then turning brown. At the end of May, small caterpillars form cocoons and by mid-June, the moths emerge.

Identifying them - When you see small white moths in your hedge, particularly at the end of the day, you know you have an infestation.

Treatment - Annual pruning will help get rid of the eggs. You can also use contact insecticide to control leafminer populations.

Spider mites

What are they? - Not spiders in fact, or insects; they are tiny (less than 1 mm) arthropods that suck plant fluid from foliage.

Identification - A large-scale infestation will be apparent through discoloration of the foliage.

Treatment - The easiest way to treat them is with a strong blast of water which will destroy their webs. You can also spray with an insecticidal soap.

Winter protection

Cedars are very resistant to our harsh winters. On the other hand, there are other conditions that can cause a lot of damage.

Install wood lattice, rigid winter fencing and geotextile to protect exposed trees from:

  • Blowing snow from snowblowers and accumulations from snowploughs
  • De-icing salt