Lemon Balm in Zone 7A — Northeast

Lemon Balm is a must-grow in any Northeast garden. Its bright, lemony flavor adds a fresh twist to teas, salads, and even desserts. Plus, the satisfaction of harvesting your own herbs, especially with our cool nights enhancing their flavor, can't be beat.

Our short growing season and the occasional late or early frost can be a challenge. But with Lemon Balm, proper timing and a little care will ensure you're harvesting plenty within our 198-day growing window.

Starting Lemon Balm indoors gives you a head start, but it's not always necessary. If you're aiming for an extra-early harvest or want to protect seedlings from those unexpected late frosts we sometimes get, it's worth considering.

Begin indoors from mid February through mid March, about six weeks before you plan to transplant. Use seed trays with a good seed-starting mix, and keep them in a warm spot with plenty of light – a sunny windowsill or under grow lights works well. Don't forget to water from the bottom to encourage strong root growth. Spring in the Northeast can be slow to arrive, so this indoor start gives your Lemon Balm a jump.

Once the danger of frost has passed, usually early April through early May, it's time to transplant your Lemon Balm seedlings outdoors. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the cooler temperatures and stronger sunlight we often see in early spring.

Space the plants 18-24 inches apart to give them room to grow. Keep an eye on the weather forecast, as a late frost is always possible, even in April. If frost threatens, cover your seedlings with blankets or cloches to protect them.

Direct sowing Lemon Balm is a simple and effective method, especially if you're not in a rush for an early harvest. Sow seeds directly into the garden from early April through early August. This works well with our relatively long days.

Prepare the soil by loosening it and removing any rocks or debris (we know all about those rocky New England soils!). Ensure the soil temperature is consistently above 60°F (15°C) for best germination. Space seeds 18-24 inches apart, or thin seedlings to that spacing later.

Lemon Balm enjoys consistent moisture, but it's not a fan of soggy conditions. In the Northeast, our even rainfall helps, but you'll still need to pay attention to watering, especially during drier spells. Aim for about 1 inch of water per week, whether from rainfall or irrigation.

Stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. Water at the base of the plant to avoid wetting the leaves excessively, which can encourage fungal diseases in our moderately humid climate.

During the cooler spring and fall months, you'll likely need to water less frequently. But during the peak of summer, especially if we have a stretch of hot, dry weather, check the soil moisture more often. Wilting leaves are a sign of underwatering, while yellowing leaves can indicate overwatering. A layer of mulch around the base of the plants helps retain moisture and suppress weeds, which is especially helpful with our variable weather.

Pruning Lemon Balm is pretty straightforward. The main goal is to keep it from getting too leggy and to prevent it from taking over your garden.

In midsummer, cut the plant back by about half to encourage bushier growth. Remove any flower stalks as soon as you see them. Lemon Balm spreads aggressively by seed, so preventing flowering helps keep it in check. As the first frost approaches in late October, you can give the plant a final trim, but leave some growth for overwintering.

You can start harvesting Lemon Balm leaves from mid June through early November. The leaves are at their best flavor before the plant starts to flower, so keep an eye on those buds.

Simply snip off the leaves you need with scissors or your fingers. Harvest regularly to encourage continued production. Lemon Balm is best used fresh, as it loses much of its flavor when dried. As the first frost approaches in late October, harvest as much as you can and use it fresh or preserve it in oil or vinegar.

Here are some common problems you might encounter with Lemon Balm in the Northeast:

Aggressive Spreading

• What it looks like: Lemon Balm popping up in unwanted areas of your garden, spreading beyond its intended space.
• What causes it: Lemon Balm spreads easily by seed and rhizomes. Our moderate rainfall and temperatures create ideal conditions for seed germination.
• How to fix/prevent it: Remove flower stalks before they go to seed. Plant Lemon Balm in a container to restrict its spread, or 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 often triggered by heat stress, long days, or drought. While the Northeast doesn't have extreme heat, extended warm spells can still cause bolting.
• How to fix/prevent it: Provide some 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. Leaves may curl, yellow, and die.
• What causes it: Powdery mildew thrives in warm days, cool nights, and moderate humidity. These conditions are common in the Northeast, especially in late summer and early fall.
• How to fix/prevent it: Improve air circulation by spacing plants adequately and pruning if necessary. 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.

Northeast Specific Challenges: Our moderate heat and moderate-to-humid conditions can favor powdery mildew, so be vigilant about air circulation and leaf moisture. The even rainfall helps with overall growth, but also requires attention to soil drainage to prevent overly wet conditions.

Lemon Balm makes a good companion for several plants in your Northeast garden:

• Tomato: Lemon Balm is said to repel tomato hornworms and other pests that can plague tomatoes.
• Squash: It can help deter squash bugs and vine borers, common pests in our region.
• Broccoli & Cauliflower: Its pest-repelling properties can protect these brassicas from cabbage moths and other insects.

Avoid planting Lemon Balm near: No specific bad companions.