Lemon balm self-sows freely and, left to flower and set seed unchecked, spreads and can take over a bed
Lemon balm self-sows freely and, left to flower and set seed unchecked, spreads and can take over a bed. Cut back or deadhead the flowering stalks before they set seed to keep it in bounds, or grow it in a container. It is a strong self-seeder that can become weedy, though it is not a listed invasive.
Promising A person has checked it against its sources. If you skip this, it still grows, just less well. The planner suggests it.
How it works
The spread is chiefly by self-sown seed. A plant left to flower sets abundant seed that drops and germinates in place, so it recurs and expands from year to year. Removing the flowering stalks before seed sets breaks that cycle. Its spread is by seed. It does not travel by the running underground stems that carry its relative mint, though a soil-grown plant can also creep somewhat at its edges.
What to do about it
Prune or deadhead the flowering stalks before they set seed, and pull self-sown seedlings while young. Grow it in a container to contain it; for a soil-grown plant, cutting around the plant's edges checks the modest edge-creep. A sterile-flowered cultivar sets no viable seed and does not self-sow.
How much it matters: No figure is stated. Left to flower and seed, lemon balm reliably volunteers and can overtake a bed; with the flower stalks cut before seed set, it stays where it was planted. The read sources call it weedy but NOT invasive, and give no count or rate. Because managing seed set is the gardener's ongoing choice, the rule only advises.
The evidence
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
While mint can spread rapidly by underground stems, lemon balm spreads by setting lots of seed and can, if allowed to go unchecked start to overtake the garden
Lemon balm, like mint spreads rapidly (becomes weedy) and can take over an herb bed
Where this rule stops
It spreads mostly by seed, unlike mint's underground runners, so stopping the seed keeps it in bounds; one source notes a little creep at the clump's edge.
Plants it applies to
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How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Details updated
- Wording made clearer
- Added to the rules
Cite this page
Milpa Gardens. "Lemon balm self-sows freely and, left to flower and set seed unchecked, spreads and can take over a bed. Cut back or deadhead the flowering stalks before they set seed to keep it in bounds, or grow it in a container. It is a strong self-seeder that can become weedy, though it is not a listed invasive." Evidence grade: Promising. https://milpa.garden/rules/lemon-balm-self-sows-freely-left-flower/
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