The lilac, which blooms so wonderfully luxuriantly and fragrantly in spring, is a neophyte. By this, experts mean non-native plant species that spread widely. Syringa, the Latin species name of the lilac, spreads very quickly via root runners, which develop in large numbers from the roots growing just below the surface of the earth. In general, the roots of the shrub are legendary - over the years they form a dense felt that is difficult to penetrate.
Lilac roots are long and strong
How lilac roots grow
The roots of the lilac run mainly just below the surface and over the years spread to a radius of several meters around the main trunk. The older the shrub gets, the more the numerous fine roots become matted, making it difficult to get through - for example because the lilac is to be planted under or a neighboring bed is to be cultivated. However, the lilac is not a pure shallow root, because depending on the condition and nutrient content of the soil, some roots can also grow deep and thus ensure the supply of the plant.
Useful: installation of a root barrier
Since numerous root runners grow from the dense network of roots near the surface and neighboring beds or foundations also have to be protected against invasion, it makes sense to introduce a root barrier when planting. Locks specially developed for bamboo have proven particularly useful for this purpose. Putting a pond liner in the planting hole or something similar, as is sometimes advised, is not sufficient. The strong roots of the lilac easily penetrate this material.
Can the roots damage foundations?
You don't need to worry: Unless your house is very old and has already been damaged by moisture, the lilac roots have no chance of penetrating. The situation is different with unsealed garden walls, which can be penetrated without any problems and happily grow over to the neighbour. Here you should definitely install a root barrier and keep the recommended minimum distance.
Remove lilacs with roots or not?
If you want or have to remove a lilac, you should always remove the root system from the ground as completely as possible. Simply sawing off the trunk is not enough to eliminate it - as a result, the stressed plant will only produce more offshoots, so that you will have to remove hundreds of mini lilacs within a radius of several meters within a very short time.
Remove root suckers: This is how it works
You can permanently remove the root runners if you uncover their base and tear them out together with the sleeping eyes. On the other hand, if you only cut them off at the surface (e.g. by simply walking over them with the lawn mower), the roots will only sprout more, resulting in more shoots forming. You can also prevent them from developing by covering the affected area with mulch material or a weed film, if at all possible.
This will keep the formation of root suckers at bay
You can reduce the formation of root suckers to a minimum if you
- keep the recommended planting distance
- do not cut back the lilacs too much
- do not damage the roots by hoeing, digging, a lawn mower or underplanting
- or leave the rootstock in the ground after cutting down an old specimen.
tips
You can also use the root suckers for easy lilac propagation.