Lemon Balm in Zone 8B — Southeast

Lemon Balm is a fantastic herb to grow in the Southeast. Its lemony flavor brightens teas, salads, and even desserts, and it thrives in our long summer. Plus, the bees absolutely love it, making it a valuable addition to any garden.

Our hot and humid summers can present some challenges with disease pressure, but with proper timing and care, Lemon Balm is a rewarding and relatively easy herb to grow here in Zone 8B. The long 255-day growing season gives you plenty of opportunity for success.

Starting Lemon Balm indoors isn't essential here in the Southeast, but it can give you a head start. If you want to get a jump on the season, sow seeds indoors from mid January through early February, about six weeks before you plan to transplant.

Use seed trays with a good seed-starting mix. Keep them warm (around 70°F) and provide plenty of light, either from a sunny window or a grow light. Bottom watering is a great way to keep the soil consistently moist without overwatering and risking damping-off. With our moderate springs, this ensures healthy seedlings ready for transplanting.

Transplant your Lemon Balm seedlings outdoors in early March through early April, once the danger of frost has passed. Before transplanting, 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. Be mindful of unexpected temperature swings during this time and protect young plants if needed.

Direct sowing Lemon Balm is a simple and effective method here in the Southeast. You can direct sow from early March through late August, giving you a wide window to get seeds in the ground.

Prepare a well-draining seedbed and ensure the soil temperature is consistently above 60°F. Sow seeds about ¼ inch deep and keep the soil moist until germination. Thin seedlings to 18-24 inches apart once they are a few inches tall.

Lemon Balm prefers moderate watering, and while it's not particularly drought-tolerant, it doesn't like to be waterlogged either. In our Southeast climate, it's crucial to balance moisture levels, especially during our hot and humid summers.

During the hotter months, especially July and August, check the soil moisture frequently. 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.

Water at the base of the plant to avoid wetting the leaves, which can encourage fungal diseases in our humid environment. Signs of underwatering include wilting leaves, while yellowing leaves can indicate overwatering. A layer of mulch, like pine straw, can help retain moisture and suppress weeds.

Pruning Lemon Balm is straightforward and helps keep the plant healthy and productive. Focus on minimal pruning to maintain its shape and prevent it from becoming too leggy.

In midsummer, cut the plant back by about half to encourage bushier growth. Remove any flower stalks as they appear to prevent the plant from self-seeding aggressively. As we approach the first frost around mid- November, you can give the plant a final trim to tidy it up before winter dormancy.

You can start harvesting Lemon Balm leaves as early as mid May here in the Southeast, and continue through late November. Expect your first harvest about 70 days after planting.

The best time to harvest is before the plant flowers, as the leaves have the most intense flavor then. Simply snip off the top leaves and stems, taking care not to remove more than a third of the plant at any one time. Regular harvesting encourages continued production throughout our long growing season. As the first frost approaches, harvest any remaining leaves you want to use, as they may decline in quality after a freeze.

Here are three common problems you might encounter with Lemon Balm in the Southeast:

Aggressive Spreading

• What it looks like: Lemon Balm rapidly expands beyond its intended area, taking over garden beds.
• What causes it: Lemon Balm spreads via seeds and rhizomes, and it thrives in our long growing season, allowing it ample time to colonize new areas.
• How to fix/prevent it: Plant Lemon Balm in containers to restrict its spread, or regularly deadhead flowers before they set seed. You can also dig up and divide the plant every few years to keep it under control.

Bolting

• What it looks like: The plant sends up a flower stalk prematurely, and the leaves become bitter or tough.
• What causes it: Bolting can be triggered by heat stress during our long summers.
• How to fix/prevent it: Provide afternoon shade to protect the plant from intense heat. Keep the soil consistently moist, and harvest leaves regularly to delay bolting.

Powdery Mildew

• What it looks like: A white or grayish powdery coating appears on the leaves and stems.
• What causes it: Powdery mildew thrives in our warm days, cool nights, and moderate humidity.
• How to fix/prevent it: Improve air circulation by spacing plants adequately and pruning dense growth. Remove affected leaves promptly. Apply neem oil or potassium bicarbonate sprays as needed.

Southeast Specific Challenges: Our hot heat, humid humidity, and wet-summer rainfall create ideal conditions for fungal diseases like powdery mildew, so good air circulation and proper watering techniques are essential. The long growing season also means Lemon Balm has plenty of time to spread aggressively, so containment strategies are crucial.

Lemon Balm is a great companion plant for several vegetables in the Southeast garden.

• Tomatoes: Lemon Balm repels tomato hornworms and other pests that can damage tomato plants.
• Squash: It helps deter squash bugs, a common problem in our region.
• Broccoli and Cauliflower: Lemon Balm can attract beneficial insects that prey on cabbage worms, protecting these brassicas.

Avoid planting Lemon Balm near fennel, as it can inhibit fennel's growth.