Growing lemon balm is easy and ideal for beginners. It is a perennial plant that grows and blooms over the spring and summer. Although it dies every winter, it returns in the spring from its rootstock. The hardy root system can survive the coldest winters as long as the plants are well mulched.
The plant grows and spreads so quickly that some gardeners consider it a weed. Despite its visible similarities to mint, lemon balm only spreads via seeds and not underground runners. Given its invasive nature, it is best to plant it next to other perennial herbs that compete for garden space. This will naturally balance its growth and avoid spreading too much. Alternatively, lemon balm can be kept in a separate pot.
Lemon balm can growth up to 3 feet tall and bushes out laterally to cover a 2 feet radius. So if you plant multiple seeds it is advisable to keep them at least 12”(one-foot) apart.
Although it can survive very cold winters if appropriately mulched, lemon balm is best suited for zones 4 to 9. For an intereactive version of the map below you can click here (USDA website).
Growing Lemon Balm
The recommend method is to sow the lemon balm seeds in flats 6 to 8 weeks before the last frost. Press the seeds gently into the soil so they don’t get too deep, as seeds require light to germinate, and mist lightly. Seeds germinate in less than two weeks and can be transplant to individual pots when the seedlings have 4 true leaves. After the last frost, plants can be transplanted out with 12” spacing in rows 2’apart.
Individual leaves may be picked as soon as the plants have become established. Cut entire stalks before the plants begin to bloom, being careful not to bruise the foliage. In the first year, two cuttings are possible. Leaves are best used fresh, as they turn brown and lose much of their scent when dried.
Care and Pruning
Once the plant has grown occasional pruning is recommend during the growing season to maintain healthy growth. If you notice that the bush is too dense and thick, the best way to thin it is to pull out some of the inner stems. You will need to mulch if live in areas where the winter temperature goes below 0°F (-18°C).
Storing and Preserving
Leaves can be stripped from stems and dried in a warm shady place. Dried leaves can be stored in an airtight container. Leaves for drying are best harvested before the plant flowers in summer, usually about the time lower leaves begin to yellow.