Urbandendro: Few details for the spruce hedge owners

Spruce hedges (Picea abies) are quite widespread in Estonia, and although they are mainly grown in non-urban areas, they are fortunately also used in settlements.
These hedges are a relatively sensible and low-maintenance solution in our conditions, but there are still some important details to pay attention to for hedge owners.


Common spruce (Picea abies) hedge in Estonia. Photo: Ravel Reiljan

When you start a planting, the plants would be worth buying from a nursery where the seeds were selected from high-quality trees and grown under the same conditions. By collecting plants from forest, we can usually get specimens with quite different growth conditions and it may happen that instead of a uniform hedge we have a hedge where some plants grow faster than others and some plants have a narrower needles than others. In addition, the plant color and dimension may also vary in some places.

After planting, it should be observed that grass will not grow under the crown of young plants.

Instead of mowing (there is threat to damage the cambium) or plucking (always risking damage to delicate roots), it would be best to use protector rings or plastic discs with a hole in the middle. Such disks are usually sold in forestry businesses, but can also be produced by yourself.
They should be used for at least a couple of years until the plants are tall enough.
Many places where a young spruce hedge grows are often easily accessible to a variety of animals that are threatening plants during the winter time. To avoid this problem, it is perhaps the easiest and most reliable way to use a repellent - such as Cervacol (in Estonia) - in this situation, you should treat plants every late autumn (shoots and tops) for some years.
After a couple of years, however, it is not advisable to let the grass grow under the spruce trees - under the young trees it grows easily and the lower branches may die - so, whenever possible, the crowns area should always be kept clean.
But mowing must be done very carefully in such places - the main damage that I have noticed to young spruce hedges is related to mowing damage. When approaching trees with a trimmer, you should always make sure that the trimmer's head protector is always towards to tree trunk, in which case there is no risk that the cambium will be damaged.
Usually alien species tend to grow in young spruce hedges - they should be picked out in the first or second year if possible - later problems may arise.
Trimming is actually a separate topic because everything depends on the growth stage and the type of hedge you want.
But - three basic things to remember:
a) In Estonia, it is not reasonable to perform trimming in the winter season.
b) Topping before the growth you need, is not a reasonable.
c) When you trimming the hedge from top, the hedge must be cleaned from cutting residues.
Occasionally it happens that the top of some spruces can be damaged or is shorter then side shoots. In such situation, a competitors should be removed or shorten.
There is common problem - where one or more plants have started to dry out in hedge.

If something like that happens, you should react quickly because it may be a fungus called Heterobasidion parviporum (the rate of spread can be up to 2 meters per year through the infected root system).

How do you understand if this is Heterobasidion?
When all the plants have been bought in one place and only one or a few of them have started to dry, it can be assumed that the small seedlings have not been infected in the nursery. In this case, you should definitely look at the dried plants for more details - are there any signs of mechanical damage in the root collar area? Or is it easy to see a resin or cracks on the strain?

If any of these things occur on the plant, there is reason to be worried. In this case, when it is seen that the plant dies - it should be gently pulled out and burn it with the root system, if possible. In the case of a young hedge, it's easy, the older plants case you should consult with specialist, there are some different possibilities.

In such a place, the new plant should not be planted before a minimum of two years.