It is not without reason that the lilac is classified as a "neophyte". This includes introduced plant species that threaten native species due to their dispersal behavior. In fact, Syringa is known to stubbornly sprout numerous root suckers within a radius of several meters of the main trunk - and often also to root entire beds densely. This behavior makes sense from a biological point of view, as it serves to reproduce, but can also drive some garden owners to despair. Lilacs that do not form runners have not yet been bred.
Lilacs should always be planted with a root barrier
Are there lilacs without stolons?
The bad news first: There are no lilac varieties that do not develop runners. However, there are ways to prevent this, for example by grafting a variety of lilac onto a rootstock that does not sprout root shoots. This is the case, for example, with lilacs grafted on privet - these sprout at most above the grafting point, which is why it must not be in the ground - but always just above it. mostly, however, lilacs are grafted onto their wild forms, which in turn busily sprout.
Combat root suckers effectively
In order to counteract an uncontrolled proliferation of the sprouting lilac, there are only two things that can help: the installation of an effective root barrier when planting and the consistent removal of foothills.
Installation of a root barrier
The most effective way to prevent unwanted mini lilacs is to dig in a suitable root barrier when planting the lilac. Many gardeners now come up with the idea of using pond liner for this purpose: this is not sufficient, as the strong lilac roots simply pierce the liner. Instead, special root barriers for bamboo have proven themselves, but also the method of simply planting the lilac together with a large clay or ceramic pot without a bottom. It is important that the barrier extends deep enough into the ground - many lilacs have already undermined concrete foundations that are 80 centimeters deep.
Remove runners consistently
It is also important to consistently remove runners. It is not enough to just cut them off at the surface or run over them with the lawnmower. The consequence of this is simply that the lilac tries to drive out even more. Instead, you must dig up each individual stolon and cut it off right at the root neck. Cutting off with a good spade is also possible, and it is also easier to do physically.
tips
Of course you can also use the root suckers for propagation. However, if you have a grafted lilac, it is most likely a shooting wild variety - which then does not look at all similar to the noble variety.