Lemon Balm: Indoor or Direct Sow Herb
How to Sow and Plant
Sowing Seed Indoors:
- Sow indoors 6-8 weeks before the last frost in spring using a seed starting kit.
- Just barely cover the seed with seed-starting formula.
- Keep the soil moist at 70 degrees F
- Seedlings emerge in 14-21 days
- As soon as seedlings emerge, provide plenty of light on a sunny windowsill or grow seedlings 3-4 inches beneath fluorescent plant lights turned on 16 hours per day, off for 8 hours at night. Raise the lights as the plants grow taller. Incandescent bulbs will not work for this process because they will get too hot. Most plants require a dark period to grow, do not leave lights on for 24 hours.
- Seedlings do not need much fertilizer, feed when they are 3-4 weeks old using a starter solution (half strength of a complete indoor houseplant food) according to manufacturer’s directions.
- If you are growing in small cells, you may need to transplant the seedlings to 3 or 4 inch pots when seedlings have at least 3 pairs of leaves before transplanting to the garden so they have enough room to develop strong roots.
- Before planting in the garden, seedling plants need to be “hardened off”. Accustom young plants to outdoor conditions by moving them to a sheltered place outside for a week. Be sure to protect them from wind and hot sun at first. If frost threatens at night, cover or bring containers indoors, then take them out again in the morning. This hardening off process toughens the plant’s cell structure and reduces transplant shock and scalding.
Sowing Directly in the Garden:
- Direct sow in average soil in full sun after danger of frost in spring.
- Remove weeds and work organic matter into the top 6-8 inches of soil; then level and smooth.
- Sow seeds evenly and lightly cover with fine soil.
- Firm the soil lightly and keep evenly moist.
- Seedlings will emerge in 14-21 days.
- Thin to 12 inches apart when seedlings are 1-2 inches tall.
How to Grow
- Mulches help retain soil moisture and maintain even soil temperatures. For herbs, an organic mulch of aged bark or shredded leaves lends a natural look to the bed and will improve the soil as it breaks down in time. Always keep mulches off a plant’s stems to prevent possible rot.
- Keep plants well-watered during the growing season, especially during dry spells. Plants need about 1 inch of rain per week during the growing season. Use a rain gauge to check to see if you need to add water. It’s best to water with a drip or trickle system that delivers water at low pressure at the soil level. If you water with overhead sprinklers, water early in the day so the foliage has time to dry off before evening, to minimize disease problems. Keep the soil moist but not saturated.
- Cut plants back by up to two-thirds after they bloom, about 40 days after emergence, to encourage new growth.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
- Divide plants every year or two in spring or early fall to control their spread.
Harvest and Preserving Tips
- Lemon balm is one of the easiest lemon-scented herbs you can grow and is suitable for flower borders, herb gardens, containers, or vegetable gardens.
- Use the fresh leaves to add to flavor to foods and teas, or toss them into your bathwater.
- Include the dried leaves in potpourri.
- To dry lemon balm, cut a bunch of stems on a sunny morning, tie them loosely and hang them in a dry, airy location out of the sun. When thoroughly dry, store in a tightly sealed glass jar in a dry, dark location, such as a cupboard, for one year.
- Lemon balm may be chopped and frozen in vegetable oil or water in ice cube trays.
Common Disease Problems
Damping Off: This is one of the most common problems when starting plants from seed. The seedling emerges and appears healthy; then it suddenly wilts and dies for no obvious reason. Damping off is caused by a fungus that is active when there is abundant moisture and soils and air temperatures are above 68 degrees F. Typically, this indicates that the soil is too wet or contains high amounts of nitrogen fertilizer. Burpee Recommends: Keep seedlings moist but do not overwater; avoid over-fertilizing your seedlings; thin out seedlings to avoid overcrowding; make sure the plants are getting good air circulation; if you plant in containers, thoroughly wash them in soapy water and rinse in a ten per cent bleach solution after use.
Powdery Mildew: This fungus disease occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and pruning. Contact your Cooperative Extension Service for fungicide recommendations.
Rust: A number of fungus diseases that cause rust colored spots on foliage and stems. Burpee Recommends: Practice crop rotation. Remove infected plants. Contact your Cooperative Extension Service for recommendations.
Septoria Leaf Spot: It is most severe during rainy seasons in closely planted gardens. It usually appears when the plants begin to set fruit. Circular spots with gray centers and dark margins appear on the lower older leaves. Fungi spores are produced and darken the center of the spots. There is a progressive loss of foliage. Burpee Recommends: Remove and destroy infected plant debris. Don't handle or brush against plants when they are wet. Rotate plantings. Remove weeds growing nearby.
Verticillium Wilt: This soil borne fungus causes a wilting of the leaves and stems on several branches. Leaf margins cup upward, leaves turn yellow and drop off. It enters the plant through the roots, migrates up the stem and plugs the plant’s transport vessels. It can also be spread by water and tools. Burpee Recommends: Remove and burn crop debris.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects that can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps who feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
European Red Mite: Tiny spider-like pests that feed on foliage causing bronzing and stunted growth. Burpee Recommends: some mulches such as a sawdust mulch or straw can help deter these mites. Check with your Cooperative Extension Service for miticide recommendations.
Spider Mites: These tiny spider-like pests are about the size of a grain of pepper. They may be red, black, brown or yellow. They suck on the plant juices removing chlorophyll and injecting toxins which cause white dots on the foliage. There is often webbing visible on the plant. They cause the foliage to turn yellow and become dry and stippled. They multiply quickly and thrive in dry conditions. Burpee Recommends: Spider mites may be controlled with a forceful spray every other day. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for miticide recommendations.
Thrips: Thrips are tiny needle-thin insects that are black or straw colored. They suck the juices of plants and attack flower petals, leaves and stems. The plant will have a stippling, discolored flecking or silvering of the leaf surface. Thrips can spread many diseases from plant to plant. Burpee Recommends: Many thrips may be repelled by sheets of aluminum foil spread between rows of plants. Remove weeds from the bed and remove debris from the bed after frost. Check with your Cooperative Extension Service for pest controls.
Whitefly: These are small white flying insects that often rise up in a cloud when plants are disturbed or brushed against. Burpee Recommends: They are difficult to control without chemicals. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for pesticide recommendations.
Lemon Balm FAQs
Can I grow lemon balm indoors? Yes, lemon balm may be grown indoors in a sunny window or under lights. Make sure it is not allowed to dry out.
Is lemon balm a good pollinator plant? Yes, the fragrant flowers of lemon balm are very attractive to bees and butterflies as well as hummingbirds.
Can I grow lemon balm in containers? Yes, lemon balm is good for containers, and growing in containers will prevent their taking over the garden.
How can I use lemon balm as a companion plant? Lemon balm repels many insects including squash bugs. Plant with members of the cucumber/squash family.
Are the flowers edible? Yes, the flowers are edible and may be used in teas or salads.