How to protect your cedars

Unless they are exposed to high winds or planted near the street, there is no need to protect Thuja occidentalis and Thuja occ. Nigra since they rarely show any damage after the winter. Some conditions, however, require more precautions.

Cedars subject to strong winds

Make sure it is protected from prevailing winds to reduce the damage associated with desiccating foliage. It should be noted that summer winds combined with sunlight can contribute to this phenomenon as well as winter winds.

Hedge planted near the street

Make sure that the foliage does not come into contact with the de-icing salt, which could be thrown by passing cars or the spreader.

Ornamental cedars

Some ornamental varieties are more fragile. This is the case of the cultivar ‘Smaragd’ (Emerald). For these pyramidal cedars, which are often made up of several trunks, it may be useful to attach all trunks together to avoid some deformations due to the accumulation of snow and ice.

Best period

It is important to protect the plants as late as possible in the fall. Most cedars, like many types of conifers, change color when winter arrives. This color change informs us that it is time to install a winter protection. It is also important to remove protection early in the spring, when the risk of large freezes is removed: the goal is to prevent temperatures from rising under the protections. Proceed on a cloudy day to prevent the risk of sunstroke.


The annual trim is without a doubt the most effective way to prevent snow and ice from causing damage to your cedars. In addition, a good watering before the first frost of autumn will allow your cedars to store the water they will need during days of thaw.

Winter protection step by step

  • Plant stakes along the hedge, on the side of the prevailing wind or the street, as the case may be;
  • Make sure the foliage of your cedars will not come in contact with the protection;
  • Attach a snow fence to the stakes;
  • Wrap the snow fence with a specially designed geotextile fabric or with a staple attached to the jute.

Errors to avoid …

  • Do not instal a jute that touches the foliage of cedars: de-icing salts could contaminate the foliage;
  • Do not instal winter protection too early in the fall. Softer temperatures may cause overheating inside the protections;
  • Stifle the cedar by tighten too much the protection: you must leave it so that it does not suffer from fungal diseases.

SOS Cedars in distress?

The overwhelming heat we have experienced in recent weeks has made us forget that fall is at our door. If your tuques and gloves are still tidy, the plants, on the other hand, have have already begun to prepare for the winter.

Since the last couple of weeks, the growth of the year is changing into wood and soon, the needles that face the trees (near the trunks) will become yellowish, then turn red before falling. Do not worry, this is the autumnal moult.

Indeed, even if conifers keep their foliage all year long, they still release a portion of it in preparation for the winter. This phenomenon allows them to overcome foliage drying that could occur during winter days when temperatures are above freezing.

Plants stressed by transplantation, drought, poor drainage or soil compaction may lose more of their foliage than they would in a year under normal conditions.

If the season is not very rainy, it is good to do some good watering at the end of October to allow the foliage to store a water reserve.

Good autumn!

Trim of your cedar

Your hedge cedar, white or black, will only require an annual trim while providing you a screen all year while other varieties do not require trim at all.

In the case of a hedge that has been neglected, of large size, or that requires specific care, it is recommended to let an arborist do the work since he is a specialist. On the other hand, if your hedge has been well maintained, it is easy to trim it yourself.

The maintenance trim is practiced during the summer season, avoiding however periods of heat and drought. In addition, avoid trimming beyond the month of August. Late trim may leave wounds that could be damaged by winter winds and stimulate new growths that would not have time to fortify before winter.

Use a hedge trimmer after installing stakes and rope. This technique will allow you to make sure to make a straight line. Do not cut more than two thirds of new growths, which are distinguished by their soft green color.

A trim made in the rules of art should have a conical shape. The base is wider than the top so the cedar can receives enough light. It should also be noted that the summit should have a rounded shape. The beautiful straight and square hedges that we see in French gardens are perfect for … French gardens! Here, your hedge could be damaged by the weight of snow and ice.

The shaping trim needs to be done early in spring, when cedars are still in dormant season. If you need to shorten or even equalize your hedge in a major way, it is better to call a professional. The same is true for varieties that are less suitable for trim, such as ‘Smaragd’ (Emerald). You have probably chosen them for their size and shape so why complicate your life by trimming them!

Is it possible to shorten a cedar hedge by a few feet?

Since cedar foliage is difficult to regenerate of old wood, it is strongly discouraged to trim it beyond the new growths, either to reduce its size in height or width. We could have an unwanted effect on the plants, in addition to leaving them bare.

When you know that a white cedar can reach 12-18 meters in height and 3 meters in width, it is better to make sure to trim them every year than to risk having them cut because the size of your hedge has become disproportionate.

Naturally, if your hedge has reached the desired height, avoid fertilizing it!

Learn more about manures and fertilizers

The fertilization of a cedar hedge is optional: it is not necessary for the good health of your hedge. However, if you wishes a fast growth, it would be interesting to apply a fertilizer rich in nitrogen during the month of May, when the soil is sufficiently heated (the nitrogen content corresponds to the first three numbers inscribed on the containers fertilizer).


On the market, there are basically 2 major types of manure: chemicals and organic.

  • Nitrogenous chemical fertilizers are easily recognized by their formulas: they usually have large numbers. Ex: 30-10-10, 20-20-20. It exist in soluble fertilizer or granules. We can use this type of fertilizer on cedar hedges without problem. On the other hand, it is very important to respect the quantities written on the containers as well as the instructions of use. Also, it is imperative to apply it in spring only (and never after June) to avoid the formation of new growth that would not have time to lignify well before winter.
  • Organic fertilizers generally have very low numbers. Ex: 4-3-9, 5-2-8. They are composed of natural elements and degrade more slowly. In addition to fertilizing cedars, they enrich the soil. They are therefore less at risk of creating imbalances in the soil. This type of fertilizer can usually be applied in May and / or September, if it is not too rich in nitrogen.


The contribution of a good compost is also an interesting alternative. You can spread ½ inch thick at the feet of your cedar each spring. In sandy soil, we recommend shrimp compost. For clay soils, forest compost is preferred. The application of compost will promote the formation of healthy and vigorous new growth in cedars that are regularly trim or that has been burned during winter, while improving the properties of your soil. Compost will also act as a mulch.

What if you can reduce your work?

As fertilizer increases the speed of growth, avoid fertilizing your hedge when it reaches the desired height!

Watering your cedar

Watering (General indications)

A freshly planted hedge should usually be watered once or twice a week during the first month in order to maintain soil moisture (this one will have been watered thoroughly during planting). Even in hot weather, it is unnecessary to water your hedge daily: we prefer a significant watering once a week rather than several small daily watering. Generally, a year or two after planting, your cedars will be well rooted and will provide for their own water needs (except in times of drought where watering may be necessary).

The best technique for watering a hedge is to install a perforated hose. Depending on the flow of water provided by your hose, watering should last 1 to 2 hours. Do not forget that a good rain counts for a watering. Once you have determined the frequency that suits your situation, you can install a timer and schedule your waterings on a regular basis.

Before watering: Check your soil moisture!

Rather than rely on foliage that will show signs when it will often be too late, we recommend you to check the soil moisture before each watering to make sure irrigation is adequate. Since there are many factors that can influence the frequency of watering, you will be able to rectify the situation before the problems occur. Dig with your fingers a few inches deep. The idea is not to know if the surface soil is wet, but to check if the amount of water available to the roots is sufficient: the soil should be moist without being saturated with water. You should be able to form a “ball” with a handful of soil without the water flowing between your fingers. If the soil is too wet, reduce the frequency and / or duration of watering. If it is too dry, be sure to thoroughly moisten the soil and then resume watering on a regular basis.

Some factors that can influence watering …

  • The nature of the soil;
  • A tree that overhangs the hedge, creating an umbrella effect;
  • The topography of the land;
  • The flow of water from your hose;
  • The frequency and quantity of rain received;
  • A perforated hose damaged or defective …

For all these reasons, we recommend you to follow the suggested tips rather than the advice of your entourage. Although they are well-intentioned, the procedure they have followed for them may not apply to you …

Watering when the plantation was done during hot weather

This situation is obviously to be avoided. However, if you have not been able to avoid the heatwave to plant your cedars, it may sometimes be necessary to water the foliage to prevent the evaporation of water by it. Indeed, since the plants draw the water they need from the roots, which may have been cut, watering the foliage could give them a little help by the time they are planted. Of course, it’s better to water in the evening, once the sun is down, or early in the morning.

Before going on vacation …

Be sure to thoroughly water the soil or install a timer. This is not difficult and you will avoid seeing your cedars dying on your return!

Your cedars turn yellowish?

This is probably a sign of root asphyxia. Either the soil and / or mulch were backfilled too high on the cedar collar, or they received too much water. Disengage the collar as needed and make sure that the water drains properly. If necessary, dig a small trench to allow water to drain and / or reduce the frequency or duration of watering.

Watering at the beginning and at the end of the season

At fall, lack of precipitation before the soil freeze can sometimes contribute to desiccation of the foliage. Unlike broadleaf that lose their leaves at fall, conifers store water in their foliage. This phenomenon will allow them to overcome foliage drying that may occur during winter, when temperatures are above the freezing point. If the season is not very rainy, it is good to have one or two good waterings at the end of October to allow the needles to store a water reserve.

For the same reason, it is essential that your newly planted cedar hedge does not lack water at the arrival of the spring’s heat.