Does it need to be in water?

It prefers very wet soil or shallow water but can grow in damp garden soil.

It spreads rapidly via underground runners, so keep it in a container if you have a small pond.

Plant guide

Water Mint.

Mentha aquatica

Pronounced MEN-tha a-KWA-ti-ka

Also known as Marsh Mint, Mint, Water Mint

Water mint is a lovely perennial that thrives in wet, marshy spots. It spreads quickly through underground runners and produces beautiful clusters of lilac flowers. You will love how its refreshing, minty scent fills the air near your pond or water feature.

At a glance

Care level: Easy
Plant type: Perennial herb
Light: Full sun to partial shade
Indoor light: Direct sun
Water: Every 1 to 2 days
Mature size: 30 to 90 cm
Growth rate: Fast
Hardiness: USDA 5 to 11
Bloom time: Mid to late summer

Care

Keep the soil consistently saturated or submerge the pot in shallow water. Watch for wilting if the soil dries out, as this plant is not drought tolerant. Prune back stems if it starts to crowd out other plants in your water garden.

Watering: Keep the soil constantly moist or keep the container partially submerged in water.
Feeding: Use a balanced aquatic plant fertilizer during the active growing season.
Pruning: Trim back overgrown stems to encourage bushier growth and prevent it from taking over.
Repotting: Repot when the roots become crowded or the plant outgrows its container.
Soil: Loamy, clay, or aquatic soil
Soil pH: 6.0 to 7.5
Temperature: -20 to 35°C
Humidity: 60 to 100%
Drought tolerance: Low
Lifespan: Perennial, long-lived as it keeps spreading by underground runners.
Fragrance: Strong
Deer and rabbits: High

Signs it needs repotting

Roots growing out of the basket mesh.
Stunted growth.
Water quality declining due to root congestion.

Safety

People: The plant is generally safe, but essential oils can irritate sensitive skin.
Children: The plant is safe for children, though the strong scent may be overwhelming for some.
Contact allergens: Handling the foliage may cause mild contact dermatitis in sensitive individuals.
Airborne allergens: Pollen may cause mild reactions in those with severe hay fever.
Edibility: While often used for tea, consume in moderation as high doses of mint oils can cause digestive distress.

How to identify it

Oval shaped, serrated green leaves
Square stems typical of mints
Dense, rounded clusters of lilac flowers
Strong, pleasant peppermint aroma
Thrives in saturated or boggy soil

Height: 0.3 to 0.9m
Spread: 0.3 to 1.5m
Leaves: green, bronze, deciduous
Flowers: lilac, pink, 0.5 to 1cm

Problems to watch for

Mint Rust · Orange pustules appear on the undersides of leaves during damp weather.

By symptom

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Growing it

Propagation: division, cuttings
When to plant: spring, summer
Overwintering: The foliage will die back in winter. Simply trim the dead stems to the water line once they turn brown.
In containers: Excellent for aquatic containers, use a mesh basket with aquatic soil.

Division

1. Remove the plant from its container.
2. Use a sharp knife to cut the root mass into smaller sections.
3. Replant the sections into fresh aquatic soil.

Plant in a submerged basket to prevent the aggressive runners from taking over your entire pond.

Grows well with

Yellow Flag Iris · They share similar moisture requirements and provide a nice height contrast.
Marsh Marigold · This plant blooms earlier, extending the season of interest in your pond.

Similar species

Spearmint · A close relative that prefers drier soil conditions.

Science

Family: Lamiaceae
Genus: Mentha
Order: Lamiales
Class: Magnoliopsida
Native range: Europe, northern Africa, and western Asia.
Conservation: Not of conservation concern.

It grows along the edges of streams and ponds, where its roots help filter water and stabilize banks.

Value to wildlife: nectar source, shelter for aquatic insects
Pollinators: bees, butterflies
Uses: pond edge planting, herbal tea, erosion control

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 6/9
Light: 7/9
Temperature: 5/9
Moisture: 9/9
Nutrients: 6/9

Taxonomy resolved against GBIF.

Questions people ask

Does it need to be in water?: It prefers very wet soil or shallow water but can grow in damp garden soil.
Is it invasive?: It spreads rapidly via underground runners, so keep it in a container if you have a small pond.

Where the name comes from

The name Mentha comes from the Greek nymph Minthe, while aquatica refers to its preference for water.

Good to know

Water mint is one of the parents of the common peppermint hybrid.
It thrives in shallow water up to 10 centimeters deep.
The leaves have a distinct, refreshing peppermint aroma when crushed.

Also in

Deer-resistant plants

Keep your water mint growing

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This guide was generated with AI on October 19, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.