Water mint is a member of the mint family (Lamiaceae), just like peppermint, winter savory, Corsican mint, catnip, lemon balm, true lavender, sweet marjoram, yellow archangel, creeping thyme, rosemary and woolly mint. It is native to Europe, Asia, Australia, New Zealand, Africa and North America. Water mint thrives in moist soils and is ideal for planting along or in ponds, beside ditches and streams, in marshes, wet dune valleys and reed grasslands. Like many other members of the mint family, it spreads easily by self-seeding and underground runners.
Water mint is also known by several regional names. This easy-care plant helps keep pond water clean and can improve the oxygen balance of the water. It is also rich in essential minerals and trace elements. The leaves can be used to make refreshing mint tea. Water mint is a hardy, perennial, vigorous and invasive plant with distinctive reddish-lilac flowers. It has a strong peppermint fragrance. Plant it in a bright, sunny location, where it is fully hardy and able to withstand cold winters. Water mint flowers from July to October and is highly attractive to bees, butterflies and other beneficial insects. In particular, the Mint Moth uses water mint as a food plant for its caterpillars. The plant dies back in winter and is not evergreen. Hardy perennial. Height: 50–60 cm.
Indoor sowing: March - April
Outdoor sowing: April - June
Germination: 10 - 21 days
Germination temp.: 15 - 20 °C
Sowing depth: shallow
Planting distance: 10 - 20 cm
Planting position: sunny - half shade
Flowering period: July - October
Harvesting period: June - November
Water mint can be sown indoors from March in seed trays filled with well-moistened potting compost. Adding a little perlite will improve drainage and aeration. Sow the seeds thinly on the surface. Do not cover the seeds with soil; simply press them gently into the compost. Keep the compost consistently moist but not waterlogged to prevent rotting. Cover the trays with a propagator lid or clear plastic wrap. The first seedlings usually appear after about 10 days. Not all seeds germinate at the same time, so it may take some time before the entire batch has emerged. Keep the temperature as constant as possible, especially at night. It is very important that both the seeds and young seedlings never dry out, so keep them well watered at all times.
Remove the lid or plastic cover as soon as the seedlings emerge. Once the seedlings are large enough to handle, transplant them into individual pots. From early May, the young plants can be hardened off by placing them outside in a sunny spot during the day for 10–14 days. After this period, plant them in a sunny, moist location with some light shade if desired. Space the plants 10 - 20 cm apart.
Water mint can also be sown outdoors from April in a sunny, moist location with optional partial shade. Sow the seeds on the surface and press them down gently. Keep the soil moist and free of weeds. The soil temperature should be at least 15 °C; otherwise sowing is not recommended. Water mint is not demanding regarding soil type, but it does require consistently moist conditions. The leaves can be harvested from June onwards and may also be dried. Stored in a sealed glass jar or plastic container in a cool, dry, dark and frost-free place, the dried leaves will keep for approximately one year.
