Lemon balm

Lemon balm is a bushy perennial herb with deliciously lemon-scented leaves and creamy-white or pale purple flowers in summer. It is vigorous and easy to grow in sun or light shade. The leaves give a lemony kick to salads, sauces and fish dishes, and make a refreshing herb tea.

Jobs to do now

  • Harvest leaves
  • Water in dry spells

Month by month

Sow

Lemon balm (Melissa officinalis) is easy to grow from seed in spring, but named varieties are only available as ready-grown plants.

Sow seeds indoors from March to May, scattering a few seeds into a small pot or tray of seed compost. Cover with a thin layer of perlite, vermiculite or finely sieved compost, then water gently. Place the pot in a heated propagator or cover with a clear plastic bag and place in a warm spot.

As soon as seedlings appear, which can take up to three weeks, take the pot out of the propagator or remove the cover. Prick out the seedlings into individual pots when they are large enough to handle.  

Transplant the young plants outdoors once all danger of frost has passed.

Grow

Traditional lemon balm is a vigorous plant that eventually makes a large leafy clump, and sends up flower stems that can reach 80cm (32in) tall. There are several cultivars too, with variegated leaves or a more compact form. The flowers are a magnet for bees.

Keep plants well watered during dry spells in summer, and cut back after flowering to encourage a fresh flush of leaves.

Lemon balm will self-seed readily, so if you don’t want more plants, remember to remove the faded flowers before they set seed.

With variegated cultivars, cut back in early summer to encourage fresh, strongly coloured shoots.

Lemon balm is a long-lived plant than can form a congested clump – so lift and divide every few years in autumn to rejuvenate plants.

Protect plants in pots from excessive winter wet by moving them into a sheltered position and raising up on pot feet to allow excess rainfall to drain away easily.

Plant

Seed-raised young plants or bought plants can be transplanted outdoors from spring onwards. Named cultivars are generally only available as ready-grown plants in spring.

Water the plants well, both before and after planting.

Choose a planting site in sun or light shade, with soil that is moist but drains freely. Lemon balm can also be planted into large pots filled with soil-based compost – a 20cm (8in) container would be ideal. 

 

Harvesting

Pick fresh leaves as required throughout summer. Leaves for drying are best harvested before plants start to flower.

Recommended Varieties

Common problems

Powdery Mildew
Powdery Mildew

Appears as a white powdery deposit over the leaf surface and leaves become stunted and shrivel.

Remedy

Keep the soil moist and grow in cooler locations.

Get involved

The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.