Lemon Balm in Zone 4A — Midwest

Lemon Balm is a fantastic herb for Midwest gardens. Its lemony scent and flavor brighten teas, salads, and even desserts. Plus, in our fertile soil and with plenty of summer sunshine, you'll have more than enough to enjoy and share with neighbors.

Our Midwest weather can be unpredictable, with late frosts and summer heat spells. But Lemon Balm is quite hardy and adaptable. Plant it at the right time, and you'll enjoy a bountiful harvest within our 128-day growing season.

Starting Lemon Balm indoors is an option. It gives you a head start, especially since our springs can be moderate-to-late. But direct sowing works just as well.

If you choose to start indoors, sow seeds late March through mid April, about six weeks before you plan to transplant. Use seed trays with a good seed-starting mix, provide warmth, and ensure they get plenty of light, either from a sunny window or a grow light. Bottom watering helps keep the soil consistently moist without damping off.

Transplanting Lemon Balm seedlings outdoors should happen mid May through mid June. This is after the risk of frost has passed. Be sure to harden off your seedlings for about a week before transplanting. Gradually expose them to outdoor conditions.

When transplanting, space your Lemon Balm plants 18-24 inches apart. This gives them room to bush out. Keep an eye on the Midwest weather forecast. Unexpected cool snaps can still happen, so be ready to cover your young plants if needed.

Direct sowing Lemon Balm is a simple and effective method for Midwest gardeners. Wait until mid May through late June when the soil has warmed up. Prepare a well-drained seedbed and sow seeds about ¼ inch deep.

Keep the soil consistently moist until germination. Thin seedlings to 18-24 inches apart once they're a few inches tall. Direct sowing avoids transplant shock. But it does mean your harvest might be a few weeks later than if you started indoors.

Lemon Balm needs moderate watering in our Midwest climate. While we often get plenty of rainfall during the summer, it's important to monitor soil moisture. Use the "finger test" – stick your finger about two inches deep into the soil. If it feels dry, it's time to water.

Generally, aim for about one inch of water per week, either from rainfall or irrigation. During summer heat spells, you might need to water more frequently. Water at the base of the plant to avoid wetting the leaves. Our moderate-to-humid climate can encourage fungal diseases if foliage stays wet.

Signs of underwatering include wilting or yellowing leaves. Overwatering can lead to root rot, indicated by soggy soil and drooping leaves. Mulching around your Lemon Balm plants helps retain moisture and keeps the soil cool during our moderate-to-hot summers.

Pruning Lemon Balm is fairly minimal. It helps keep the plant tidy and productive. In midsummer, cut back the plant by about half. This prevents it from getting too leggy and encourages fresh growth.

Remove any flower stalks as they appear. This prevents the plant from self-seeding. Lemon Balm can be quite aggressive, and you don't want it taking over your garden. As the first frost approaches around mid- September, you can give the plant one final trim to tidy it up before winter.

You can start harvesting Lemon Balm leaves late July through late September in the Midwest. This is about 70 days after planting. The best flavor is before the plant flowers. Harvest leaves anytime they look big enough to use.

Pinch or cut off stems just above a leaf node. This encourages the plant to produce more leaves. Regular harvesting keeps the plant productive throughout the season. For the best flavor, use fresh Lemon Balm immediately after harvesting. It tends to lose its flavor when dried.

As the first frost approaches in mid- September, harvest any remaining leaves. You can use them fresh or make a tincture. Don't worry if you don't get every single leaf. The plant is quite hardy and will likely return next spring.

Here are three common problems you might encounter with Lemon Balm in the Midwest:

Aggressive Spreading

• What it looks like: Lemon Balm popping up in areas where you didn't plant it, quickly taking over garden beds.
• What causes it: Lemon Balm spreads easily through seeds and rhizomes. Our fertile soil provides ideal conditions for rapid growth.
• How to fix/prevent it: Remove flower stalks before they go to seed. Consider planting Lemon Balm in a container to restrict its spread. Regularly pull up any unwanted seedlings.

Bolting

• What it looks like: The plant sends up a flower stalk prematurely. The leaves become bitter and less flavorful.
• What causes it: Bolting can be triggered by summer heat spells or drought stress.
• How to fix/prevent it: Provide shade during the hottest part of the day. Keep the soil consistently moist. Harvest leaves frequently to encourage vegetative growth.

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. Our Midwest summers can provide these conditions.
• How to fix/prevent it: Improve air circulation by spacing plants adequately. Remove affected leaves. Apply neem oil or potassium bicarbonate sprays. Milk spray (1 part milk to 9 parts water) can also be effective.

Midwest Specific Challenges: Our moderate-to-hot summers and moderate-to-humid humidity can promote both bolting and powdery mildew in Lemon Balm. Be sure to provide adequate water and air circulation. Monitor plants regularly for any signs of these problems.

Lemon Balm makes a good companion plant for several vegetables in the Midwest garden. It helps repel certain pests and attract beneficial insects.

Good companions include tomatoes, squash, and broccoli. The strong scent of Lemon Balm can deter tomato hornworms and squash bugs. It also attracts pollinators that benefit broccoli and cauliflower.

Avoid planting Lemon Balm near rue. Rue is known to inhibit the growth of many herbs, including Lemon Balm.