Lemon Balm in Zone 7B — Desert Southwest

Lemon Balm is a fantastic addition to any Desert Southwest garden. Its lemony flavor brightens teas and dishes, and it's incredibly satisfying to harvest your own herbs. Plus, it’s a perennial, so it'll come back year after year, giving you a reliable supply of fresh flavor.

Desert gardening can be challenging with our extreme heat and alkaline soil, but Lemon Balm is surprisingly adaptable. With proper timing and a little extra care, you can enjoy this herb throughout our long, 245-day growing season.

Starting Lemon Balm indoors is an option, especially if you want a head start on the season. Sow seeds indoors from late January through mid February, about six weeks before you plan to transplant. This gives them a chance to get established before our very-early spring kicks in.

Use seed trays or small pots filled with a good seed-starting mix. Keep the soil consistently moist by bottom watering to avoid disturbing the delicate seedlings. Provide warmth and plenty of light – a sunny windowsill or grow lights will work well.

Transplant your Lemon Balm seedlings outdoors from mid March through mid April, after the last expected frost. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the desert sun and wind.

Choose a location with full sun to partial shade and space the plants 18-24 inches apart. Be mindful of unexpected temperature swings that can still happen in early spring here. Water them well after transplanting to help them settle in.

Direct sowing Lemon Balm is a straightforward method, especially since our growing season is so long. Sow seeds directly into the garden from mid March through late August. This gives you a wide window to work with, even for succession planting.

Prepare the soil by loosening it and mixing in some compost. Lemon Balm prefers slightly moist soil for germination. Keep the soil consistently moist until the seedlings emerge. Thin the seedlings to 18-24 inches apart once they are a few inches tall.

Lemon Balm appreciates consistent moisture, which is crucial in our arid Desert Southwest climate. While it's not drought-tolerant, it also doesn't like soggy soil, so finding the right balance is key. The monsoon season can give it a boost, but supplemental watering is still necessary.

During the hotter months, especially before the monsoon arrives, water deeply about 2-3 times per week, providing about 1 inch of water each time. Use the "finger test" – if the top 2 inches of soil feel dry, it's time to water. During the cooler spring and fall, you can reduce watering to once or twice a week.

Water at the base of the plant to avoid wetting the leaves, which can encourage fungal diseases. Signs of underwatering include wilting and yellowing leaves. Overwatering can lead to root rot, indicated by mushy, brown roots and yellowing leaves.

Mulching around your Lemon Balm plants with organic matter like wood chips or straw helps retain moisture and regulate soil temperature. This is especially important in our extreme heat.

Pruning Lemon Balm is simple and helps keep it healthy and productive. The main goal is to prevent it from becoming too leggy and to control its spread. Regular pruning also encourages bushier growth and better flavor.

In midsummer, cut the plant back by about half to prevent it from becoming too leggy. Also, remove any flower stalks as soon as you see them. This prevents self-seeding, which can quickly lead to Lemon Balm taking over your garden.

As the first frost approaches around mid- November, you can give the plant a final trim. Leave some foliage to help it through the winter. It will likely die back somewhat, but should return vigorously in the spring.

You can expect your first Lemon Balm harvest about 70 days after planting, so from late May through late November. The best time to harvest is before the plant flowers, as the leaves have the most intense flavor at this stage. Don't worry, with regular pruning it will keep producing.

Look for healthy, vibrant green leaves as a sign they're ready to harvest. Simply snip off the stems with scissors or pruning shears, taking care not to damage the main plant. Harvest regularly to encourage new growth and prevent the plant from becoming too overgrown.

Lemon Balm is best used fresh, as it loses much of its flavor when dried. Harvest only what you need for immediate use. As the first frost approaches in mid- November, harvest as much as you can and consider making Lemon Balm tea or pesto to preserve the flavor.

Here are the top 3 problems you might encounter with Lemon Balm in the Desert Southwest:

Aggressive Spreading

• What it looks like: Lemon Balm popping up in unwanted areas of your garden. It spreads via seeds and rhizomes (underground stems).
• What causes it: Lemon Balm is a vigorous grower and can quickly take over if not contained. In our long growing season, it has ample opportunity to spread.
• How to fix/prevent it: Plant Lemon Balm in a container to restrict its roots. Regularly remove flower stalks to prevent seed dispersal. Dig up and remove unwanted plants as soon as you see them.

Bolting

• What it looks like: The plant sends up a flower stalk prematurely. The leaves become bitter and less flavorful.
• What causes it: Bolting is triggered by heat stress, which is a common issue in our Desert Southwest summers.
• How to fix/prevent it: Provide afternoon shade during the hottest months. Ensure consistent watering to prevent drought stress. Remove flower stalks as soon as they appear to maintain leaf quality.

Powdery Mildew

• What it looks like: A white or grayish powdery coating on the leaves and stems.
• What causes it: Powdery mildew thrives in warm days, cool nights, and moderate humidity. While our humidity is low, the monsoon season can create favorable conditions.
• How to fix/prevent it: Improve air circulation by spacing plants adequately 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.

Desert Southwest Specific Challenges: Our extreme heat and intense sun can stress Lemon Balm, making it more susceptible to bolting and powdery mildew. Consistent watering is crucial to prevent drought stress, but be mindful of overwatering during the monsoon season. Providing afternoon shade can also help protect the plant from sunscald.

Lemon Balm makes a great companion plant for several vegetables in your Desert Southwest garden.

Good companions include:

• Tomatoes: Lemon Balm can help repel tomato hornworms and other pests.
• Squash: It can deter squash bugs and vine borers.
• Broccoli and Cauliflower: Lemon Balm can attract beneficial insects that prey on cabbage worms.

Avoid planting Lemon Balm near rue. Rue is known to inhibit the growth of many herbs and vegetables, and Lemon Balm is no exception.