Lemon Balm in Zone 9B — Gulf Coast

Lemon balm is a fantastic herb to grow here on the Gulf Coast. Its lemony, minty flavor adds a refreshing zing to teas, salads, and even desserts. Plus, it's incredibly satisfying to snip fresh leaves from your garden for a quick culinary boost, knowing you grew it yourself.

Our long growing season gives you ample opportunity to cultivate lemon balm, but we also have to deal with high humidity and disease pressure. Don't worry, with a little planning and attention to timing, you can enjoy a bountiful harvest from early April all the way through late December.

Starting lemon balm indoors is definitely an option, but honestly, with our mild winters, direct sowing is usually the easier route. However, if you want a head start, you can sow seeds indoors from mid December through early January, about six weeks before you plan to transplant. Use seed trays with a good seed-starting mix and keep them warm and consistently moist by watering from the bottom.

Place the trays under grow lights or in a very sunny window. Our early spring warmth here on the Gulf Coast means you'll want to keep a close eye on them and get them outside as soon as possible!

Transplant your lemon balm seedlings outdoors from late January through late February. This gives them a chance to settle in before the real heat of summer hits. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Space them 18-24 inches apart in a well-drained area. Keep an eye on the weather forecast – we can still get some cool snaps during this time, so be prepared to cover them if a frost is predicted.

Direct sowing lemon balm is easy and effective here on the Gulf Coast. You can sow seeds directly into your garden beds from late January through late September. Choose a spot with well-drained soil, and gently rake the seeds into the top layer.

Keep the soil consistently moist until the seedlings emerge. Thin them to 18-24 inches apart once they're a few inches tall. Direct sowing is generally preferred as the plants get established in their permanent location quicker without transplant shock.

Watering is crucial for lemon balm, especially with our Gulf Coast climate. While lemon balm prefers moderate moisture, our high humidity can make things tricky. During the hotter months, you'll likely need to water deeply about twice a week, providing about 1 inch of water each time.

Use the "finger test" to check the soil moisture about 2 inches deep. If it feels dry, it's time to water. It's generally better to water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our humid environment. Overwatering can lead to root rot, so watch out for yellowing leaves. Underwatering will cause wilting and stunted growth.

Mulching around your lemon balm plants with pine straw or shredded leaves will help retain moisture and suppress weeds. This is especially important during our hot, humid summers.

Lemon balm requires minimal pruning, but a little maintenance goes a long way. Cut back the plant by about half in midsummer to prevent it from becoming leggy. This will also encourage new growth and keep it producing flavorful leaves.

Be sure to remove any flower stalks as they appear, as this will prevent the plant from self-seeding aggressively. Towards the end of the season, as our first frost approaches around mid- December, you can give the plant a final trim to tidy it up for the winter.

You can start harvesting lemon balm leaves as early as early April, about 70 days after planting. The best flavor comes before the plant flowers, so harvest frequently to encourage leaf production. Look for healthy, green leaves that are free from blemishes.

To harvest, simply snip off the stems with scissors or pruning shears. Avoid taking more than one-third of the plant at a time to ensure continued production. Lemon balm is best used fresh, as it loses much of its flavor when dried. Harvest all the way through late December, enjoying fresh lemon balm well into our mild winters.

Lemon balm is generally easy to grow, but here on the Gulf Coast, we face a few common problems: aggressive spreading, bolting, and powdery mildew.

Aggressive Spreading

• What it looks like: Lemon balm popping up in unwanted areas of your garden.
• What causes it: Self-seeding and spreading via underground roots. Our long growing season gives it plenty of time to spread.
• How to fix/prevent it: Plant in a container to restrict its growth. Remove flower stalks before they go to seed. Regularly pull up any unwanted seedlings.

Bolting

• What it looks like: The plant sends up a flower stalk, and the leaves become bitter and tough.
• What causes it: Heat stress, long days, and drought stress can trigger bolting.
• How to fix/prevent it: Provide afternoon shade during the hottest part of the day. Keep the soil consistently moist. Harvest frequently to encourage leaf production.

Powdery Mildew

• What it looks like: A white or grayish powdery coating on the leaves.
• What causes it: Fungal disease that thrives in warm days, cool nights, and moderate humidity. Our high humidity can exacerbate the problem.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning. Remove affected leaves. Apply neem oil or potassium bicarbonate sprays. A milk spray (1 part milk to 9 parts water) can also be effective.

Gulf Coast Specific Challenges: Our hot, humid climate and wet-year-round rainfall create ideal conditions for fungal diseases like powdery mildew. Be vigilant about monitoring your plants and taking preventative measures to ensure a healthy harvest.

Lemon balm makes a great companion plant for several vegetables in the Gulf Coast garden. Plant it near tomatoes and squash to help repel pests like whiteflies and squash bugs. It also benefits broccoli and cauliflower by attracting beneficial insects that prey on aphids.

Avoid planting lemon balm near any members of the mint family, as they can be quite aggressive and compete for resources.