Plum and lilac root sprouts: prevention and permanent control

Why do root sprouts form on plum and lilac?

Root sprouting is a natural response of the tree to reproduce. On plum (Prunus domestica) and lilac (Syringa vulgaris) especially, because these are commonly used as rootstock for other varieties. The rootstock tries to establish itself and sends up shoots from the roots, especially if the tree is damaged or stressed. This usually happens near the graft point but can also emerge from deeper root systems.

This is frustrating because you think you have solved the problem but the sprouts grow straight back. Many gardeners chop them off with a spade or knife, which makes it worse. Every root wound triggers even more sprouts. The solution is patience and the right technique: pull them, do not cut them.

The rootstock: why you have this problem

If you planted a young plum tree or lilac, chances are you did not get an identical tree root to tip, but a graft: the nice variety on a stronger root system (the rootstock). This has advantages: faster growth, better drought tolerance, suited to your soil type. But the rootstock naturally wants to reproduce by its own variety, not via the graft above it.

If that graft union is not deep enough under the ground, or if the tree suffers wounds, the rootstock reactivates its plan: it sends shoots upward. These shoots are genetically the rootstock itself, not the pretty variety you want. They grow more vigorous and hard than the variety you grafted, and they regrow if you cut them. This is not disease or weakness, but pure biology. Not sure whether your plum or lilac is even in the right spot before you fight this for years? On gardenworld.app you see it first in a preview of your own garden.

Why cutting makes it worse

Cutting and chopping is the biggest mistake. You think logically: pull the shoot, it comes back, so cut it flush and treat the wound with pruning sealer or a saw. This triggers the tree to produce even more shoots. Every cut wound is a distress signal: "I am under attack, send reserves to the roots to survive."

The stem wounds also give bacteria and fungi an entry point. The tree escalates its self-defense. Each cut produces two to three new shoots. After a few seasons you have a tangled network of thick shoots around the base and you drive yourself mad. A good share of the root sprout complaints gardeners have are actually self-inflicted, triggered by cutting in the first place.

Pulling instead of cutting: the right technique

The only approach that works: pull the shoots out. This takes care but is effective. Grasp the shoot at its base and pull it gently from the ground instead of cutting it off. This takes some physical effort on your part but does no harm to the tree.

When you pull the shoot out, you also remove the growth point at the root base. With cutting you leave that growth point in place, and it thinks: "I am not dead, one branch is gone, let me send ten new shoots." With pulling you give the root base a clear signal that something serious is happening, and after repeated pulling the tree gives up. This takes months to years, but it works.

Damaging roots: the biggest pitfall

When you pull on the shoot and at the same time loosen soil around it with a spade, you damage side roots. This does not reduce sprouting, it makes it worse. Every damaged root becomes a place where more shoots can grow. The same applies to lawn mowers and rotavators: much root sprout trouble flourishes in gardens where the rotavator runs along the garden path every spring.

So pull the shoot gently without using tools in the soil around it. Grasp it at the base with both hands, place your foot on the ground close by for stability, and pull slowly upward. If it resists, let go, wait two weeks, and try again. The root connection weakens each time, and eventually it comes loose easily.

When root sprouts are worst: during mowing

Root sprouts grow most actively when you allow them. But much worse: if you regularly overlook them and they grow beyond your control zone. Then you hit them with a rotavator, blade mower or even a spade, exactly what you must not do.

Check your tree monthly, especially from May to October. Keep the area around the stem base free of grass and weeds so you spot small shoots before they become strong branches. The younger you catch them, the easier they come out and the less root damage.

Protect your tree against mowing damage

The worst trigger for root sprouts is accidental mowing damage. You go with the lawn mower against the stem, the spade hits roots just below the surface, or you drive the rotavator too close to the tree. This causes wounds that trigger the tree to sprout from roots.

If you just planted a young tree, put a protective ring around the stem base: a plastic tree guard, tied sticks or just keep a circle of 60 centimetres grass-free around the stem. This also protects against dogs, aphids and weeds. After three to four years the tree is strong enough to manage root sprouting better.

Start with deep planting: prevention

The best defense against root sprouts starts at planting. Plant the tree deeper than it was in the nursery. The graft point (a thick knot just above the roots) must be at least 5 to 10 centimetres below ground. The deeper the graft, the less easily the rootstock sends roots to the surface.

This deeper planting does mean you must be extra careful with soil compaction and settling in the first year. A tree with a deep graft grows first deep with its roots, then sideways, which is slower than a shallow planting. Patience pays off: this tree gives you years of fewer root sprout problems.

Step by step

Step 1: Identify all shoots

Check your tree weekly from May to October. Place a stick next to every shoot you see so you do not lose track.

Step 2: Pull gently

Grasp the shoot at the base with both hands. Place your foot close by on the ground for support. Pull slowly upward without twisting sideways until it comes loose. Do this weekly.

Step 3: Remove the base

If a shoot breaks, try to dig out the base from the ground without damaging side roots. This can be done with a small sharp spade at a shallow angle.

Step 4: Protect the stem base

Keep grass and weeds free within a metre round the stem. Never use a lawn mower or rotavator close to the tree.

Step 5: Repeat weekly in season

Make this a routine from May to October. As months pass you will see fewer returns.

Frequently asked questions

How many times must I pull them before they really stop? On a mature tree with deep-rooted rootstock this can take two to three seasons, pulling once a month during the growing season. You will see them return less vigorously. After two years most are gone for good, a few late sprouts disappear by the third season.

Can I cut them and then use pruning sealer? No, sealer only triggers more sprouting. Your wound looks neat but underground the tree interprets it as a weakness. Pull them, nothing more.

What if they grow from different spots around the tree? That indicates scattered root damage. Check your mowing tools and ensure they never touch the stem. Pull all shoots weekly to monthly, then let them grow until August (no growth under drought stress). This further weakens the rootstock.

Can I use herbicide against root sprouts? Chemical solutions work poorly on plum and lilac rootstocks, they are stubborn. Glyphosate is also banned for private use in Belgium and the Netherlands, and besides, you would poison your good tree too. Do not do this.

See it in your own garden first

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