How to Grow Lemon Balm Seeds
Grow Guide #2391
Binomial name: Melissa officinalis
Life Cycle: Perennial
This 'How to Grow' guide details everything a home gardener needs to know to plant, grow and care for Lemon Balm (Melissa officinalis).
When to Sow Lemon Balm Seeds
Lemon Balm is a perennial plant that grows year round in most climates. Use the table below to identify the best time of year to sow lemon balm seeds in your climate.
Lemon Balm plants can be difficult to eradicate once they are established in the garden. Choose a permanent position in a garden bed or grow them in containers to prevent them spreading into unwanted areas.
Lemon Balm plants commonly self-seed in the garden. Self-seeding plants drop seeds onto the soil at the end of the season that may germinate and grow without help the following season. Choose a position where new plants will be welcome. If you do not want lemon balm to become established in your garden, deadhead plants before they can drop seed or grow them in containers.
Lemon Balm plants are best grown in full sun or part shade. Choose a location that will receive at least 3 hours of full sun each day.
Lemon Balm plants need a well drained soil enriched with plenty of organic matter. Prepare soil by weeding it thoroughly, digging it over to loosen it and adding aged animal manure or compost. Keep the area free of weeds until planting. Learn more about preparing soil for planting here.
Lemon Balm plants can be grown in containers. If possible choose a variety that’s recommended for container growing. Use a good quality potting mix and make sure your container is large enough for mature plants; a minimum of 10 litres is recommended for lemon balm. During the growing season, keep in mind that container grown plants may need additional fertiliser to encourage healthy growth.
How to Sow Lemon Balm Seeds
Lemon Balm seeds do not require any treatment (eg soaking, stratification) before sowing.
Lemon Balm seeds grow best when they are raised in trays or other containers and transplanted to the garden once established.
- Fill trays, punnets or jiffy pots with a good quality seed-raising mix, or use soil starter pellets.
- Sow seeds 3mm deep.
- Keep soil moist but never wet or dry.
- Seeds should germinate in around 7-14 days at a soil temperature of 19-21°C.
- Transplant seedlings to the garden once they have their first true leaves and are large enough to handle (usually 5-10cm tall).
- Plant out, spacing plants 50cm apart.
How to Grow Lemon Balm
Lemon Balm plants may need watering during the growing season. Water when the soil is dry about 5cm below the surface (test this by scratching away a little soil with your finger). Water deeply in the early morning or late afternoon. Avoid watering the leaves of plants to avoid fungal diseases. Learn more about watering here.
If soil was well prepared no extra fertiliser should be necessary. In poor soil or to give your plants an extra boost, application of a high-nitrogen fertiliser or one formulated for leafy greens or herbs can be beneficial:
- Apply slow release fertiliser at the recommended rate when transplanting or when seedlings are 5-10cm tall.
- Apply liquid fertiliser at the recommended rate and frequency during the growing season.
Lemon Balm plants may die back in cold weather. Cut plants back just above ground level in late autumn, or prune off dead foliage when new leaves emerge in spring.
How to Harvest Lemon Balm
Lemon Balm should be ready to harvest in approximately 60-70 days.
Leaves are ready to harvest when they are large enough to eat, and can be harvested as needed. Harvest leaves by pinching off the outer leaves, leaving some on the plant for future growth. Lemon balm can be stored short term in a perforated plastic bag in the fridge, or the stems can be placed in a glass or jar of water to keep them hydrated. For longer term storage, lemon balm can be dried, though it's flavour and fragrance are stronger when it is used fresh.
Common Problems when Growing Lemon Balm
Like all plants, lemon balm is susceptible to some pests, diseases and other problems. Below is a list of the most common problems gardeners encounter when growing lemon balm plants:
- Aphids are small (2-4mm long) sap-sucking insects that congregate on the new shoots or the undersides of leaves. They can cause leaves to wilt or become discoloured, and also excrete honeydew which can attract ants and other insect pests. To manage aphids, remove them by spraying with a garden hose, apply a soap or alcohol spray, or encourage predatory insects to your garden. Read more about aphids here.
- Slugs and snails are molluscs that feed on tender leaves and shoots, mostly at night, leaving slimy trails behind them. Control them by removing their hiding places, keeping free range poultry, collecting them by torchlight or by placing traps. Read more about slugs and snails here.
- Whitefly is a sap-sucking insect related to aphids. They are often found in large numbers on the underside of leaves and will swarm in clouds when disturbed. Plants may have yellowing leaves or may wilt, and growth will be slowed. Whitefly can be removed with a garden hose or sprayed with soap spray. Badly affected plants should be destroyed. Attracting beneficial insects that will prey on whitefly can be beneficial. Read more about managing whitefly here.