Troubleshooting
Watermint problems — and how to fix them
Watermint (Mentha aquatica) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Aggressive spreading
Runners colonise a pond margin or bed rapidly and can swamp neighbours. Confine it to an aquatic basket or contained area and divide regularly to keep it in check.
Mint rust
Orange pustules on leaf undersides, common in crowded, damp stands. Remove and destroy affected stems; thin growth for airflow; badly hit clumps may need cutting back hard.
Drying out
Unlike garden mints it will not tolerate drought; leaves crisp and the plant declines if the soil dries. Keep it in constantly wet ground or standing water.
Leaf-eating beetles
Mint leaf beetles and their larvae can strip foliage. Pick off by hand where practical; healthy, vigorous clumps usually recover quickly.
Prevent watermint problems before they start
Most watermint issues are care-mismatch, not bad luck. Dial in the basics:
Looking for watermint in general rather than its problems? Read the full watermint care guide — light, water, soil and feeding.
Watermint problems — FAQ
Why is my watermint aggressive spreading?
Runners colonise a pond margin or bed rapidly and can swamp neighbours. Confine it to an aquatic basket or contained area and divide regularly to keep it in check.
Why is my watermint mint rust?
Orange pustules on leaf undersides, common in crowded, damp stands. Remove and destroy affected stems; thin growth for airflow; badly hit clumps may need cutting back hard.
Why is my watermint drying out?
Unlike garden mints it will not tolerate drought; leaves crisp and the plant declines if the soil dries. Keep it in constantly wet ground or standing water.
Why is my watermint leaf-eating beetles?
Mint leaf beetles and their larvae can strip foliage. Pick off by hand where practical; healthy, vigorous clumps usually recover quickly.