Lemon Balm in Zone 5A — Great Plains

Lemon Balm is a fantastic herb for Great Plains gardens. Its lemony scent and flavor add a bright note to teas, salads, and even desserts. In our region, where the intense sunshine brings out the best in herbs, Lemon Balm thrives, offering a rewarding harvest throughout the growing season.

Our Plains climate can be unpredictable, with extreme temperature swings and the occasional hail risk. But with a 168-day growing season, you can manage Lemon Balm successfully with careful timing. Whether you start seeds indoors or sow directly, you'll have plenty of time to enjoy its fresh flavor.

Starting Lemon Balm indoors is a good option, especially if you're itching to get your hands dirty before the weather fully cooperates. Begin in early to late March, about six weeks before you plan to transplant. This gives the seedlings a head start.

Use seed trays with a good seed-starting mix. Provide warmth (a heat mat helps) and plenty of light – a grow light is ideal, especially given our variable spring weather. Don't forget to water from the bottom to encourage strong root growth.

Transplant your Lemon Balm seedlings outdoors in late April through late May, once the danger of hard frost has passed. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the wind and temperature fluctuations common in the Plains.

Space the plants 18-24 inches apart to allow for their bushy growth habit. Be mindful of late-season cold snaps when transplanting. Keep row covers handy just in case!

Direct sowing Lemon Balm is a straightforward method, and it works well in our prairie soil. Sow seeds directly into the garden from late April through mid July. This gives you a wide window to work with.

Ensure the soil is well-prepared and the temperature is consistently above 60°F. Lightly cover the seeds with soil, and keep the area moist until they germinate. Thin seedlings to 18-24 inches apart once they are a few inches tall.

Lemon Balm needs moderate watering, which means paying attention to the weather. Unlike some herbs that thrive on neglect, Lemon Balm appreciates consistent moisture. While not drought-tolerant, it tolerates more moisture than many other herbs.

During our hot Plains summers, check the soil moisture regularly. Stick your finger about two inches deep – if it feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or irrigation.

Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our low-to-moderate humidity. Overwatering can lead to root rot, so watch for yellowing leaves. Mulching around the base of the plant helps retain moisture and regulate soil temperature, which is especially helpful with our extreme temperature swings.

Pruning Lemon Balm is simple and helps maintain its vigor. In midsummer, cut the plant back by about half to prevent it from becoming leggy. This encourages bushier growth and a more abundant harvest.

Regularly remove flower stalks to prevent self-seeding, as Lemon Balm can be quite aggressive. At the end of the season, as the first frost approaches in early October, give the plant a final trim. You can either leave it in place for winter or bring a portion indoors to continue enjoying fresh leaves.

You can expect your first harvest of Lemon Balm in early July through mid October, about 70 days after planting. The best flavor comes from leaves harvested before the plant flowers. So, harvest regularly to encourage continued leaf production.

Look for healthy, vibrant green leaves as your sign of readiness. Simply snip off the stems with scissors or pruning shears, taking care not to damage the main plant. Regular harvesting encourages bushier growth and a longer harvest period.

As the first frost approaches in early October, harvest as many leaves as possible. While Lemon Balm loses some flavor when dried, you can still preserve the remaining harvest for teas and other uses throughout the winter.

Lemon Balm, while generally easy to grow, can face a few common problems in the Great Plains: 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: Lemon Balm spreads by seed and rhizomes (underground stems), quickly colonizing new areas.
• How to fix/prevent it: Remove flower stalks before they go to seed. Plant Lemon Balm in a container or raised bed to contain its spread. Regularly dig up and remove unwanted shoots.

Bolting

• What it looks like: The plant sends up a flower stalk prematurely, and the leaves become bitter or tough.
• What causes it: Bolting is triggered by heat, long days, or drought stress, all common occurrences in our Plains summers.
• How to fix/prevent it: Provide afternoon shade during the hottest part of the day. Keep the soil consistently moist. Harvest regularly to encourage leaf production.

Powdery Mildew

• What it looks like: A white or grayish powdery coating on the leaves, stems, and sometimes fruit. Leaves may curl, yellow, and die.
• What causes it: Powdery mildew thrives in warm days, cool nights, and moderate humidity, all of which we can experience in the Plains. Dry leaf surfaces actually favor it.
• How to fix/prevent it: Improve air circulation by spacing plants adequately and pruning. Remove affected leaves promptly. Apply neem oil or potassium bicarbonate sprays. A milk spray (1 part milk to 9 parts water) can also be effective.

Great Plains Specific Challenges: The hot heat and variable rainfall in the Plains can stress Lemon Balm, making it more susceptible to bolting and powdery mildew. Consistent watering and providing afternoon shade can help mitigate these issues. The aggressive spreading can be managed with containment strategies.

Lemon Balm makes a great companion plant for several vegetables in the Great Plains garden.

• Tomato: Lemon Balm repels tomato hornworms and other pests that can damage tomato plants.
• Squash: Its strong scent can deter squash bugs and vine borers, common pests in our region.
• Broccoli and Cauliflower: Lemon Balm can help repel cabbage moths and other brassica pests.

Avoid planting Lemon Balm near fennel, as it can inhibit the growth of many plants.