Lemon Balm in Zone 6B — Mountain West

Lemon Balm is a must-have herb for any Mountain gardener. Its bright, citrusy flavor adds a refreshing twist to teas, salads, and even desserts. Plus, the satisfaction of harvesting your own herbs, knowing they thrived in our intense sun and cool nights, is hard to beat.

Our short growing season and alkaline soil can present challenges, but with careful timing and a few tricks, Lemon Balm is very manageable. With about 163 days from last frost to first, you'll have plenty of time to enjoy this versatile herb.

Starting Lemon Balm indoors in our Mountain climate is an option, especially if you want a head start on the season. Begin in early to late March, about six weeks before you plan to transplant outdoors. This gives the seedlings a chance to develop before our last frost.

Use seed trays and a good seed-starting mix. Provide warmth and plenty of light – a grow light works well, as our spring weather can be unpredictable. Water from the bottom to encourage strong root growth and prevent damping off. Keep in mind that our late spring means you'll need to be patient and protect seedlings from any unexpected cold snaps.

Transplant your Lemon Balm seedlings outdoors in late April through late May, once the danger of frost has passed. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense sun and cooler temperatures.

Space plants 18-24 inches apart to allow for their bushy growth habit. Be prepared to protect young transplants from late-season hail, which can be common in our region. Row covers are helpful.

Direct sowing Lemon Balm is also a viable option in our Mountain climate. Sow seeds directly into the garden in late April through mid July, once the soil has warmed up. The later you sow, the less time you have to harvest.

Prepare the soil well, ensuring it's loose and well-draining. Lemon Balm prefers a soil temperature of at least 60°F for germination. Space seeds 18-24 inches apart, or thin seedlings to this spacing once they emerge. Direct sowing can be convenient, but you'll need to be diligent about weeding and watering, especially during our dry spells.

Watering Lemon Balm correctly is crucial in our dry Mountain climate. While Lemon Balm prefers moderate moisture, it's important to avoid both overwatering and underwatering. The key is to find the right balance, especially considering our low humidity and minimal rainfall.

During the peak of summer, when temperatures are around 85°F, water deeply about 1-2 inches per week. Use the "finger test" – if the top two inches of soil feel dry, it's time to water. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases, even in our dry climate.

In spring and fall, when temperatures are cooler, reduce watering frequency. Overwatering can lead to root rot, especially in our alkaline soil. Signs of underwatering include wilting leaves and stunted growth. Overwatering can cause yellowing leaves and a mushy stem. Mulching around the base of the plant helps retain moisture and regulate soil temperature, which is especially beneficial with our intense sun.

Pruning Lemon Balm is fairly simple and helps maintain its shape and productivity. In midsummer, cut back the plant by about half to prevent it from becoming leggy and encourage new growth. This also helps to keep the plant from getting too unruly.

Regularly remove any flower stalks that appear, as flowering can reduce leaf production and flavor. Plus, Lemon Balm is known to self-seed aggressively, so removing flowers prevents unwanted spread. As the first frost approaches in early October, you can give the plant a final trim, but leave some foliage to help it overwinter.

You can expect your first Lemon Balm harvest in early July through mid October, about 70 days after planting. The best time to harvest is before the plant flowers, as the leaves have the most intense flavor then. Look for healthy, green leaves that are at least a few inches long.

To harvest, simply snip off the stems with scissors or pruning shears, taking care not to damage the main plant. You can harvest continuously throughout the growing season, encouraging new growth. As the first frost approaches in early October, harvest as much as you can and preserve it by drying or freezing for use during the winter months. Fresh Lemon Balm is always best, as it loses flavor when dried.

Here are some common problems you might encounter with Lemon Balm in our Mountain gardens:

Aggressive Spreading

• What it looks like: Lemon Balm popping up in unexpected places throughout your garden.
• What causes it: Lemon Balm self-seeds readily and spreads via underground rhizomes.
• How to fix/prevent it: Plant in a container to restrict its spread, or be diligent about removing flower stalks before they set seed. Regularly dig up and remove unwanted plants.

Bolting

• What it looks like: The plant sends up a flower stalk prematurely, and the leaves become bitter or tough.
• What causes it: In our region, bolting can be triggered by heat stress during the peak of summer, especially if the plant doesn't get enough water.
• How to fix/prevent it: Provide afternoon shade during the hottest part of the day. Keep the soil consistently moist. Remove flower stalks as soon as they appear to encourage continued leaf production.

Powdery Mildew

• What it looks like: A white or grayish powdery coating on the leaves and stems.
• What causes it: Powdery mildew can occur in our region due to warm days and cool nights, combined with low humidity which is ideal for spore dispersal.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning to open up the canopy. Remove affected leaves. Apply neem oil or potassium bicarbonate sprays. A milk spray (1 part milk to 9 parts water) can also be effective.

Mountain West Specific Challenges: Our intense UV radiation can stress Lemon Balm, making it more susceptible to bolting and powdery mildew. Providing some afternoon shade can help mitigate this. Also, our alkaline soil can affect nutrient availability, so amend the soil with compost to improve drainage and nutrient uptake.

Lemon Balm makes a great companion plant for several vegetables in our Mountain gardens. Plant it near tomatoes and squash to help repel pests and improve growth. It also benefits broccoli and cauliflower by attracting beneficial insects that prey on common pests.

Avoid planting Lemon Balm near any plants that prefer very dry conditions, as its moderate watering needs could create an environment that's too moist for them.