Lemon Balm in Zone 5B — Mid-Atlantic

Lemon Balm is a fantastic addition to any Mid-Atlantic garden. Its lemony scent and flavor are delightful in teas, salads, and even as a mosquito repellent. Plus, the plant thrives in our four seasons, giving you plenty of fresh herbs from late spring well into fall.

While our humid summers can present challenges, and deer pressure is always a concern, Lemon Balm is relatively easy to grow here with the right timing. Our 178-day growing season provides ample opportunity to enjoy this versatile herb.

Starting Lemon Balm indoors in the Mid-Atlantic isn't strictly necessary, but it can give you a head start, especially if you're eager for an early harvest. Starting seeds indoors from early to late March, about six weeks before the last expected frost, allows you to get a jump on the season.

Use seed trays with a good seed-starting mix, providing warmth and plenty of light – a simple shop light works wonders. Keep the soil consistently moist by bottom watering – setting the tray in a shallow dish of water lets the seedlings soak up what they need, preventing damping off. With our moderate spring weather, indoor starting is a good insurance policy.

Transplanting Lemon Balm outdoors in the Mid-Atlantic is best done from mid April through mid May, after the risk of a hard freeze has passed. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Choose a spot with full sun to partial shade and space the plants 18-24 inches apart to allow for their bushy growth. Keep an eye on the weather forecast, as we sometimes get unexpected cold snaps even in late spring.

Direct sowing Lemon Balm is a simple and reliable method for Mid-Atlantic gardeners. Sow seeds directly into the garden from mid April through late July.

Prepare the soil by loosening it and removing any weeds, ensuring the soil temperature is at least 60°F. Sow seeds about ¼ inch deep, spacing them 18-24 inches apart to give them room to grow. Direct sowing works well here, but be patient as germination might be a bit slower compared to starting indoors.

Lemon Balm enjoys moderate watering, which is essential in our Mid-Atlantic climate. While we get reliable rainfall, the humidity and moderate-to-hot summer heat can still dry out the soil quickly.

During the spring, check the soil moisture regularly using the "finger test" – stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or irrigation. As the summer heat intensifies and the humidity rises, water at the base of the plant to avoid wetting the leaves, which can encourage fungal diseases.

Signs of underwatering include wilting leaves and slow growth, while overwatering can lead to yellowing leaves and root rot. A layer of mulch around the base of the plants helps retain moisture and suppress weeds, which is especially helpful with our clay soils.

Pruning Lemon Balm is fairly straightforward and helps keep the plant healthy and productive in our Mid-Atlantic gardens. In midsummer, cut the plant back by about half to prevent it from becoming leggy and to encourage fresh growth.

Regularly remove any flower stalks to prevent self-seeding, as Lemon Balm can spread aggressively. As the first frost approaches in mid- October, give the plants a final trim to tidy them up for the winter.

You can start harvesting Lemon Balm in the Mid-Atlantic around late June, about 70 days after planting, and continue harvesting through late October. The best flavor comes from leaves harvested before the plant flowers.

To harvest, simply snip off the leaves as needed, taking care not to remove more than one-third of the plant at a time to ensure continued production. The leaves are best used fresh, as they lose their flavor when dried. As the weather cools in the fall, harvest as much as you can before the first frost.

Lemon Balm, while generally easy to grow, can encounter a few common problems in the Mid-Atlantic region.

Aggressive Spreading

• What it looks like: Lemon Balm popping up in unwanted areas of your garden, spreading beyond its intended space.
• What causes it: Lemon Balm readily self-seeds and spreads via underground runners, especially in our favorable climate.
• How to fix/prevent it: Plant in containers to restrict root spread, remove flower stalks before they seed, and be vigilant about pulling up unwanted seedlings.

Bolting

• What it looks like: The plant sends up a flower stalk prematurely, and the leaves become bitter and less flavorful.
• What causes it: Bolting can be triggered by heat and long days, which are common during our Mid-Atlantic summers.
• How to fix/prevent it: Provide some afternoon shade during the hottest part of the day, ensure consistent moisture, and regularly harvest leaves to encourage vegetative growth.

Powdery Mildew

• What it looks like: A white or grayish powdery coating on the leaves, stems, and sometimes the fruit, causing leaves to curl, yellow, and die.
• What causes it: Powdery mildew thrives in warm days, cool nights, and moderate humidity, all of which we experience in the Mid-Atlantic.
• How to fix/prevent it: Improve air circulation by spacing plants adequately and pruning as needed. Remove affected leaves promptly. Apply neem oil or potassium bicarbonate sprays. A milk spray (1 part milk to 9 parts water) can also be effective.

Mid-Atlantic Specific Challenges: Our moderate-to-hot heat and humid humidity, combined with even rainfall, create ideal conditions for powdery mildew and can stress Lemon Balm, potentially leading to bolting. Consistent monitoring and proactive measures are key to keeping your plants healthy.

Lemon Balm makes a great companion plant for several vegetables in the Mid-Atlantic garden. It's particularly beneficial when planted near tomatoes and squash, as it helps repel pests like tomato hornworms and squash bugs. The strong scent of Lemon Balm can also deter cabbage moths, making it a good companion for broccoli and cauliflower. Avoid planting Lemon Balm near any members of the mint family, as they can compete for resources and become overly aggressive in this region.