Lemon Balm in Zone 8A — Desert Southwest

Lemon Balm is a fantastic herb for Desert Southwest gardens. Its lemony scent and flavor make it a refreshing addition to teas, salads, and even desserts. Plus, the satisfaction of growing your own herbs, especially one as versatile as lemon balm, is hard to beat.

Our extreme heat and alkaline soil can be tough on plants, but with careful timing, you can enjoy a thriving Lemon Balm patch. The Desert Southwest's long, 265-day growing season gives you plenty of opportunities for planting and harvesting.

Starting Lemon Balm indoors in the Desert Southwest is an option, but not always necessary given our long growing season. If you want a head start, 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, provide warmth (a heat mat helps), and ensure they get plenty of light, either from a grow light or a very sunny window. Bottom watering is key here – set the tray in a shallow dish of water and let the soil soak it up to avoid disturbing the tiny seeds.

Transplant your Lemon Balm seedlings outdoors from early March through early April, once the danger of hard frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This prevents transplant shock from our bright Desert Southwest sun. Space plants 18-24 inches apart to allow for good air circulation and growth. Keep an eye on the nighttime temperatures, as we can still get some dips into the 30s during this time.

Direct sowing Lemon Balm is a straightforward method that works well in our climate. Sow seeds directly into the garden from early March through early September. Prepare the soil by loosening it and amending with compost. Lemon Balm seeds need light to germinate, so don't bury them too deeply – just barely cover them with soil. Keep the soil consistently moist until the seedlings emerge. Thin seedlings to 18-24 inches apart. Direct sowing later in the season (late summer) is a great way to get a fall harvest.

Watering Lemon Balm correctly is vital for its survival in our arid Desert Southwest climate. While it prefers moderate moisture, it's not drought-tolerant and needs consistent watering, especially during our extreme summer heat.

• Seasonal Watering: In spring and fall, water deeply about 2-3 times per week, providing about 1 inch of water each time. During the monsoon season, let the rainfall supplement your watering, but still check the soil moisture. In the intense heat of summer (especially June/July), you may need to water every day or every other day to prevent stress.
• The Finger Test: Stick your finger about 2 inches deep into the soil near the base of the plant. If it feels dry, it's time to water.
• Water at the Base: Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases, especially during periods of monsoon moisture.
• Signs of Under/Overwatering: Underwatering will cause the leaves to wilt and turn yellow. Overwatering can lead to root rot, with leaves becoming yellow and mushy.
• Mulching: Apply a layer of organic mulch around your Lemon Balm plants to help retain soil moisture and regulate soil temperature.

Pruning Lemon Balm helps keep it healthy and productive throughout the growing season. This herb can get a little leggy and unruly without regular trimming.

Cut back your Lemon Balm plants by about half in midsummer (around July) to encourage bushier growth and prevent them from becoming too leggy. Remove flower stalks as they appear to prevent self-seeding, as Lemon Balm can spread aggressively. As the first frost approaches in late November, give your plants a final trim to tidy them up for the winter.

Harvesting Lemon Balm is easy and can be done throughout much of the year in the Desert Southwest. You can expect your first harvest around mid-May, about 70 days after planting.

Harvest leaves anytime they are large enough to use, but the best flavor is usually before the plant flowers. Simply snip off the stems with scissors or pruning shears, taking care not to damage the plant. Regular harvesting encourages continued production. As the first frost approaches in late November, harvest as much as you can and dry or freeze it for winter use.

Here are common problems to watch out for with Lemon Balm in the Desert Southwest:

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 stems. This is exacerbated by our long growing season.
• How to fix/prevent it: Remove flower stalks before they set seed. Plant in a container to restrict its spread, or be prepared to regularly pull up unwanted seedlings.

Bolting

• What it looks like: The plant sends up a flower stalk prematurely, and the leaves become bitter.
• What causes it: Triggered by heat and drought stress, common occurrences in our Desert Southwest summers.
• How to fix/prevent it: Provide afternoon shade during the hottest months. Water consistently to prevent drought stress. Remove flower stalks as soon as you see them to encourage continued leaf production.

Powdery Mildew

• What it looks like: A white or grayish powdery coating on the leaves.
• What causes it: Fungi that thrive in warm days and cool nights, especially during the monsoon season when humidity fluctuates.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning. Remove affected leaves. A milk spray (1 part milk to 9 parts water) can be surprisingly effective.

Desert Southwest Specific Challenges: The extreme heat and arid humidity of the Desert Southwest can stress Lemon Balm, making it more susceptible to bolting and powdery mildew. Consistent watering, afternoon shade, and good air circulation are crucial for success. Our alkaline soil can also be a challenge, so amend the soil with compost to improve drainage and nutrient availability.

Lemon Balm can be a helpful companion plant in your Desert Southwest garden. It's said to repel certain pests and attract beneficial insects.

Good companions include tomatoes, squash, broccoli, and cauliflower. Lemon Balm repels tomato hornworms and other pests that can damage tomatoes. It also helps to deter squash bugs and cabbage moths, which can be problematic for squash, broccoli, and cauliflower.