Lilac has been an integral part of German gardens for centuries. The flowering tree, which grows up to four meters high, not only impresses with its dense growth and dark green foliage, but above all with its lush, fragrant flowers. The plant, which comes from southern Europe, is also robust and easy to care for - which is noticeable, among other things, in the roots. These spread practically everywhere.
Is lilac a shallow-rooted or deep-rooted plant?
Lilac (Syringa vulgaris) is both a shallow and deep rooter, as it spreads both near the surface and at depth, depending on soil conditions and nutrient availability. To avoid unwanted spread, a stable rhizome barrier should be used when planting.
Deep-rooted or shallow-rooted? Or even both?
It is impossible to say exactly whether the common lilac (Syringa vulgaris) is a deep- or shallow-rooted plant. In fact, the shrub spreads underground both in a fan shape and close to the surface and into the depths - depending on the composition of the soil at its location and at what depth there are nutrients and water. The deep-reaching roots provide the lilac with everything it needs - and the meter-long ring-shaped roots provide plenty of runners through which numerous varieties can multiply. By the way: Plants generally only root as deeply as they absolutely have to. If there is a nutrient and water-rich layer on the surface, the roots of a classic deep-rooted plant do not extend several meters into the depths.
Important: Be sure to adhere to plant positions
Since lilac roots spread so widely, you should definitely adhere to the recommended planting distances not only from neighboring plants, but also from walls etc. It is usually recommended to choose a distance between one and one and a half meters for vigorous varieties. Lilac hedges can of course be planted more densely.
Dig up the lilacs completely - otherwise there is a risk of a lilac invasion
Many lilac varieties - not all - develop so-called root runners, which can appear several meters away from the main trunk. You should keep this in mind if you want to remove a lilac - simply sawing off the trunk usually only results in hundreds of root shoots suddenly bursting out. For this reason, you should always dig up the roots as completely as possible. For the same reason, it makes sense to install a root barrier when planting to control the growth of the lilac and its spread.
Tip
A simple pond liner (€78.00 on Amazon) or something similar is not sufficient as a root barrier because the strong roots simply pierce it. Instead, you should use a more stable rhizome barrier.