It is not without reason that lilacs are classified as “neophytes”. This refers to introduced plant species that threaten native species through their spreading behavior. In fact, Syringa is known for stubbornly sprouting numerous root runners within several meters of the main trunks - and often densely rooting entire beds. This behavior makes sense from a biological point of view, as it helps with reproduction, but it can also drive some garden owners to despair. Lilacs that do not form runners have not yet been bred.
Are there lilacs without runners?
There is no lilac without runners. To prevent unwanted growth, a root barrier can be used or the runners can be consistently removed. Lilac can also be grown by grafting on a base without root shoots.
Are there lilacs without runners?
The bad news first: There are no lilac varieties that do not produce runners. However, there are ways to prevent this, for example by grafting a noble lilac variety onto a rootstock that does not produce root shoots. This is the case, for example, with lilacs grafted onto privet - these sprout at most above the grafting point, which is why it must not be in the ground - but always just above it. Most of the time, however, noble lilacs are refined into their wild forms, which in turn sprout diligently.
Effectively combat root suckers
In order to counteract the uncontrolled proliferation of sprouting lilacs, only two things help: the installation of an effective root barrier during planting and the consistent removal of runners.
Installing a root barrier
The most effective method 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 because the strong lilac roots simply pierce the liner. Instead, special root barriers for bamboo have proven successful, as has the method of simply planting the lilac in 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 penetrated 80 centimeter deep concrete foundations.
Consistently remove runners
It is also important to consistently remove runners. It is not enough to simply cut them off on the surface or run over them with a lawnmower. The result of this is simply that the lilac tries even harder to sprout. Instead, you have to dig up each individual runner and cut it off directly at the root collar. Parting with a good spade is also possible and is physically easier to do.
Tip
Of course you can also use the root runners for propagation. However, if you have a refined lilac, it is most likely a shooting wild variety - which then looks nothing like the noble variety.
