Lemon Balm in Zone 6A — Northeast

Lemon Balm is a fantastic addition to any Northeast garden. Its lemony fragrance and flavor are perfect for teas, salads, and even desserts, adding a refreshing zest to your summer cooking. Plus, it's incredibly satisfying to grow your own herbs, especially when cool nights here in the Northeast intensify their flavor.

Our short growing season and the occasional late spring frost can be a bit of a challenge, but Lemon Balm is pretty forgiving. With a little planning and attention to timing within our 178-day window, you can easily enjoy a bountiful harvest.

Starting Lemon Balm indoors isn't essential, but it can give you a head start, especially if you're itching to get growing after a long winter. Sow seeds indoors from early to late March, about six weeks before you plan to transplant them outside. Use seed trays with a good seed-starting mix, keep them warm, and provide plenty of light – a simple shop light works wonders.

Don't forget to water from the bottom! This helps prevent damping off, a common problem when starting seeds indoors. Given our late springs here in the Northeast, starting indoors is a good way to ensure you get a good harvest before the first frost.

Once the danger of frost has passed (usually mid April through mid May here in the Northeast), it's time to transplant your Lemon Balm seedlings outdoors. Before you do, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind, preventing transplant shock.

Space your plants 18-24 inches apart to give them room to grow. Even in mid-May, keep an eye on the weather forecast here in the Northeast; a late frost can still happen!

Direct sowing Lemon Balm is a simple and effective method, especially if you don't want to fuss with starting seeds indoors. Sow seeds directly into the garden from mid April through late July. Just make sure the soil has warmed up a bit.

Prepare the soil by loosening it and removing any rocks or debris – our rocky New England soil can be tough! Space the seeds 18-24 inches apart, and keep the soil consistently moist until they germinate. The downside to direct sowing is that you might not get as early of a harvest compared to starting indoors.

Lemon Balm likes consistent moisture, but it doesn't want to be waterlogged. In our Northeast climate, with moderate heat, moderate-to-humid humidity, and even rainfall, watering needs vary throughout the season. During the spring, natural rainfall is often enough, but as summer progresses, you'll need to supplement.

Stick your finger about two inches deep into the soil; if it feels dry, it's time to water. Aim for about an inch of water per week, either from rainfall or irrigation. Watering at the base of the plant is best to avoid wetting the leaves, which can encourage fungal diseases in our humid climate.

Yellowing leaves can indicate overwatering, while wilting leaves suggest underwatering. A layer of mulch, like shredded bark or straw, can help retain moisture and keep the soil cool.

Pruning Lemon Balm is pretty straightforward. In midsummer, give the plant a haircut by cutting it back by about half. This prevents it from getting too leggy and encourages bushier growth.

Also, be sure to remove any flower stalks as soon as they appear, unless you want the plant to self-seed everywhere. Lemon Balm can be quite aggressive! Before the first frost in mid- October, you can give it one last pruning to tidy it up for the winter.

You can start harvesting Lemon Balm leaves as soon as the plant is big enough, typically from late June through late October here in the Northeast. The best flavor comes from leaves harvested before the plant starts to flower. Look for healthy, vibrant green leaves.

To harvest, simply snip off the stems with scissors or pruners. Regular harvesting encourages the plant to produce more leaves. As the first frost approaches in mid- October, harvest as many leaves as you can and preserve them by drying or freezing for use throughout the winter.

Here are three common problems you might encounter growing Lemon Balm in the Northeast:

Aggressive Spreading

• What it looks like: Lemon Balm popping up in unwanted areas of your garden, quickly taking over.
• What causes it: Lemon Balm spreads easily via seeds and underground rhizomes. Our moderate heat and even rainfall in the Northeast provide ideal conditions for it to thrive.
• How to fix/prevent it: Plant Lemon Balm in a container to restrict its growth, or deadhead flowers before they set seed. Regularly pull up any unwanted seedlings.

Bolting

• What it looks like: The plant sends up a flower stalk prematurely, and the leaves become bitter or tough.
• What causes it: Bolting can be triggered by heat or drought stress. Although the Northeast doesn't have brutal summers, a sudden heat wave can still cause bolting.
• How to fix/prevent it: Provide shade during hot spells, keep the soil consistently moist, and remove flower stalks as soon as they appear.

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 – all common conditions in the Northeast.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning. Remove affected leaves, and apply neem oil or potassium bicarbonate spray. A milk spray (1 part milk to 9 parts water) can also be effective.

Northeast Specific Challenges: Our moderate heat and moderate-to-humid humidity in the Northeast can create favorable conditions for powdery mildew on Lemon Balm. Monitor your plants regularly and take preventative measures to ensure a healthy harvest.

Lemon Balm makes a great companion plant for several vegetables in the Northeast garden. Plant it near tomatoes and squash to help repel pests like squash bugs and tomato hornworms. It also benefits broccoli and cauliflower by attracting beneficial insects that prey on cabbage worms.

Avoid planting Lemon Balm near rue or other herbs in the mint family, as they can compete for resources and attract similar pests.