Lemon Balm in Zone 8B — Desert Southwest

Lemon Balm is a fantastic addition to any Desert Southwest garden. Its bright, lemony flavor is delicious in teas, salads, and even desserts, and it's incredibly satisfying to grow your own herbs in our challenging climate. Plus, it's known for its calming properties, perfect for unwinding after a long day in the desert sun.

While our extreme heat and alkaline soil present unique challenges, Lemon Balm's adaptability and the timing of our two growing seasons make it a manageable and rewarding plant to cultivate. With a 279-day growing season, you'll find plenty of opportunities to enjoy fresh Lemon Balm.

Starting Lemon Balm indoors is an option, especially if you want a head start on the season. Begin in early to late January, about six weeks before you plan to transplant outdoors. Use seed trays with well-draining potting mix, and provide warmth – a heat mat can be helpful.

Ensure your seedlings get plenty of light, either from a sunny window or a grow light. Bottom watering is a great trick for seedlings; it encourages strong root growth and prevents damping off. Given our very-early spring start in the Desert Southwest, getting those seeds going indoors can give you a jump!

Transplant your Lemon Balm seedlings outdoors in late February through late March, after the last expected frost. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This prevents shock from our intense Desert Southwest sun.

Space your plants 18-24 inches apart to allow for good air circulation and growth. Keep an eye on the weather forecast during this time – an unexpected cold snap can still occur, so be prepared to cover your seedlings if necessary.

Direct sowing Lemon Balm is a simple and effective method in our climate, especially given our two growing seasons. Sow seeds in late February through early September, ensuring the soil temperature is consistently above 60°F. Prepare the soil by loosening it and adding compost to improve drainage and fertility.

Sow seeds about ¼ inch deep and keep the soil consistently moist until germination. Thin seedlings to 18-24 inches apart once they are a few inches tall. Direct sowing is a great option for a continuous supply of Lemon Balm, especially if you stagger your plantings.

Watering Lemon Balm properly is crucial for success in the Desert Southwest. While it needs moderate moisture, overwatering can be just as detrimental as underwatering. During the hotter months, from late May through late September, you'll likely need to water deeply 2-3 times per week, depending on rainfall.

Use 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, adjusting based on monsoon moisture. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our arid environment.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to yellowing leaves and root rot. A layer of organic mulch, like shredded bark or compost, can help retain moisture and regulate soil temperature. Remember, even with monsoon rainfall, our extreme heat can quickly dry out the soil.

Pruning Lemon Balm helps maintain its shape and encourages bushier growth. In midsummer, typically late June through mid-August, cut back your plants by about half to prevent them from becoming leggy. This also encourages a fresh flush of growth as we head into our second growing season.

Remove any flower stalks as they appear to prevent self-seeding, as Lemon Balm can become quite aggressive. As the first frost approaches in early December, you can give your plants one final trim to tidy them up for the winter. Leave some foliage to help protect the crown of the plant.

You can begin harvesting Lemon Balm leaves as early as early May, about 70 days after planting, and continue harvesting through early December. The best flavor is typically before the plant flowers, so keep an eye out for those flower stalks and harvest before they fully develop. Harvest in the morning after the dew has dried for the best flavor.

To harvest, simply snip off the stems with leaves, taking care not to remove more than a third of the plant at any one time. This encourages continued production. Lemon Balm is best used fresh, as it loses much of its flavor when dried. As the first frost approaches, harvest as much as you can and use it to make teas or infusions.

Here are some common 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.
• What causes it: Lemon Balm readily self-seeds and spreads via underground rhizomes. In our long growing season, it has ample time to spread.
• How to fix/prevent it: Regularly remove flower stalks before they go to seed. Consider growing Lemon Balm in a container to restrict its spread.

Bolting

• What it looks like: The plant sends up a flower stalk prematurely, and the leaves become bitter or tough.
• What causes it: Triggered by heat and drought stress, both common in our Desert Southwest summers.
• How to fix/prevent it: Provide afternoon shade during the hottest months. Ensure consistent watering, especially during heat waves. Cut back the flower stalks as soon as you see them.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves and stems.
• What causes it: Fungi that thrive in warm days, cool nights, and moderate humidity. Our monsoon season can create these conditions, even though our humidity is generally low.
• How to fix/prevent it: Improve air circulation by spacing plants adequately. Remove affected leaves promptly. Apply neem oil or potassium bicarbonate sprays.

Desert Southwest Specific Challenges: Our extreme heat and low humidity can stress Lemon Balm, making it more susceptible to bolting and powdery mildew. Consistent watering and afternoon shade are crucial for summer survival. The monsoon season, while providing much-needed moisture, can also create conditions favorable for fungal diseases.

Lemon Balm makes a great companion plant for several vegetables in the Desert Southwest garden. It is said to deter pests, which is a bonus in our environment.

Good companions include tomatoes, squash, broccoli, and cauliflower. Lemon Balm is believed to repel tomato hornworms and squash bugs, common pests in our gardens. It also attracts beneficial insects that prey on other garden pests.

Avoid planting Lemon Balm near fennel, as it can inhibit its growth. Because Lemon Balm spreads, keep it away from delicate herbs that might get crowded out.