Water mint
Mentha aquatica
Botanical family: Lamiaceae
Mentha aquatica is the wild European water mint, a relative of spearmint (Mentha spicata) and peppermint (M. × piperita, a spontaneous hybrid of M. aquatica × M. spicata). An emergent plant with an upright habit of 40-80 cm, oval toothed purplish leaves, a powerful camphor-menthol scent. Natural habitat: marshes, riverbanks, damp ditches throughout Europe.
Sun to partial shade
Mud or waterlogged soil, feet in shallow water (0-10 cm)
Emergent plant, feet in permanent water, also tolerates waterlogged soil on the bank
Very hardy (-25 °C)
Overwinters in your zone
Insect-pollinated (pink flowers in clusters July-September, very nectar-rich)
Role in permaculture
An aromatic companion of the edible pond: summer flowering in the very trough of the nectar season (July-August), edible camphorous aromatic foliage (drink, salads, English yogurt sauce), and a refuge for many pollinators. A native species to protect. Like all mints, to be contained in a submerged basket to avoid colonisation by rhizomes.
Good companions
Traditional companion planting (benefit not demonstrated)
Insects attracted or useful
Seasons & availability
A perennial mint of pond margins: aromatic leaves picked from April to October, and for drying when the plant comes into flower; pink flowers, much visited by bees, from July to September; it is increased mainly by division or a piece of root, as seed does not come true, mints crossing readily.
Available: April, May, June, July, August, September, October.
Guidance for the oceanic / temperate climate; it may vary with your region, altitude, exposure and growing method.
Sources
- Plants For A Future, « Mentha aquatica » (pfaf.org/user/Plant.aspx?LatinName=Mentha+aquatica)
- Tela Botanica, « Mentha aquatica L. » (tela-botanica.org/bdtfx-nn-41945-description)
- La Ferme de Sainte Marthe, « Réussir la culture de la menthe » (fermedesaintemarthe.com/en/blogs/comment-reussir-la-culture-de/reussir-la-culture-de-la-menthe)
Nutritional & medicinal properties
For educational purposes. Not a substitute for medical advice. Effects depend on the form, the dose and personal context.
Precautions & contraindications
Only harvest in clean water, away from livestock: aquatic plants eaten raw and picked downstream of pastures can carry the larvae of the large liver fluke (Fasciola hepatica, fascioliasis); sufficient cooking destroys them, so cook if in doubt. The plant also moderately accumulates water pollutants: for consumption, the pond must be fed with roof rainwater in a rural area, away from local sources of contamination, and the notion 'rainwater = pure water' needs updating since the study by Cousins et al. (2022, Environmental Science & Technology), which shows that PFOA levels in rainwater exceed US drinking-water health advisories even in remote regions, and PFOS levels often do (see the concept 'Rainwater quality'). Avoid high doses in pregnant women and infants, as the essential oil of water mint is rich in menthone and menthofuran. No risk of toxic confusion: all mints are edible.
Family behaviour: Lamiaceae
In general, Lamiaceae are aromatics (basil, mint, thyme, rosemary, sage, lavender, lemon balm, savory). Their essential oils are reputed to bother some insects, but in a trial cited by Parker et al. (2013), sage, thyme and mint planted near cabbages did not reduce their pests. Their flowers are much visited by pollinators.
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Before you forage
This plant is often gathered from the wild. Only pick what is abundant, never a protected species, and never uproot a whole plant (roots) without the landowner's permission. Rules vary by country and region, check locally.
Key takeaways
- • Prefers sun to partial shade exposure.
- • Ideal soil: mud or waterlogged soil, feet in shallow water (0-10 cm).
- • Classic companion: Cattail (bulrush).