Lemon Balm in Zone 5B — Midwest

Lemon Balm is a workhorse herb for us Midwest gardeners. The citrusy, minty flavor is fantastic in teas, salads, and even summer cocktails. Plus, it's incredibly satisfying to grow something that bounces back year after year, even after our harsh winters.

Our Midwest weather definitely throws curveballs, especially with those temperature swings in spring and the occasional summer heat spells. But with a 168-day growing season, we have plenty of time to get a good harvest of Lemon Balm if we time things right.

Starting Lemon Balm indoors is an option, though honestly, it's not always necessary here in the Midwest. If you're itching to get a head start, aim to sow seeds indoors in early to late March. That gives you about 6 weeks before you'd want 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. Water from the bottom to avoid damping off. Given our moderate-to-late springs, starting indoors can give you a jump, but direct sowing is usually just as successful.

Transplanting Lemon Balm seedlings outdoors is best done in late April through late May. Before you move them permanently, you'll want to harden them off. Give them about a week of gradual exposure to the outdoors.

Space your Lemon Balm plants about 18-24 inches apart to give them room to grow into their bushy shape. Keep an eye on the forecast because we can still get a late frost that could nip your young plants.

Direct sowing Lemon Balm is super easy and often the most practical method for us Midwest gardeners. Wait until late April through mid July to sow your seeds directly into the garden. The soil should be workable and starting to warm up.

Prepare your garden bed by loosening the soil and removing any weeds. Scatter the seeds lightly over the surface and gently press them into the soil. Space them about 18-24 inches apart. Keep the soil moist until the seedlings emerge.

Lemon Balm likes consistent moisture, which is usually pretty manageable with our Midwest rainfall. But don't assume Mother Nature will take care of everything! Especially during those summer heat spells, you'll need to pay attention.

Stick your finger about 2 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 supplemental watering. Water at the base of the plant, rather than overhead, to help prevent fungal diseases in our moderate-to-humid climate.

If the leaves start to droop, it's a sign of underwatering. Yellowing leaves can indicate overwatering. A good layer of mulch, like shredded leaves or straw, will help retain moisture and keep the soil cool during those summer heat spells.

Lemon Balm is pretty low-maintenance when it comes to pruning. In midsummer, you can cut the plant back by about half to encourage bushier growth and prevent it from getting too leggy. This is especially important if you want to keep harvesting leaves throughout the season.

Be sure to remove any flower stalks as they appear, unless you want Lemon Balm taking over your entire garden. It's an aggressive self-seeder! At the end of the season, before our first frost hits around early October, you can give it one last trim to tidy it up.

You can start harvesting Lemon Balm leaves as soon as the plant is big enough to handle it, usually starting in early July through mid October. The leaves will have the best flavor before the plant starts to flower. Just snip off the stems with a pair of scissors or pruning shears.

When you harvest, aim to take about one-third of the plant at a time. This encourages new growth and keeps the plant producing throughout the season. Lemon Balm is best used fresh, as it tends to lose its flavor when dried.

As the first frost approaches in early October, harvest as much as you can and consider making Lemon Balm tea or infused oils to preserve the flavor. You can also pot up a small plant to bring indoors for the winter, though it might not thrive as well as it does outdoors.

Here in the Midwest, we face a few common problems with Lemon Balm: aggressive spreading, bolting, and powdery mildew.

Aggressive Spreading

• What it looks like: Lemon Balm popping up everywhere in your garden where you didn't plant it.
• What causes it: Lemon Balm is a prolific self-seeder. The seeds spread easily, and the plant can also spread through its roots.
• How to fix/prevent it: Deadhead the flowers before they go to seed. Consider planting Lemon Balm in a container to restrict its spread. You can also dig up and divide the plant in the spring to keep it under control.

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, which we definitely experience during our summer heat spells.
• How to fix/prevent it: Provide some afternoon shade during the hottest part of the day. Keep the soil consistently moist. Harvest regularly to encourage new leaf growth and prevent the plant from putting all its energy into flowering.

Powdery Mildew

• What it looks like: A white or grayish powdery coating on the leaves and stems.
• What causes it: Powdery mildew is a fungal disease that thrives in warm days, cool nights, and moderate humidity – a pretty common scenario in our Midwest summers.
• How to fix/prevent it: Improve air circulation by spacing plants adequately and pruning to open up the canopy. Remove affected leaves. You can also try spraying with neem oil or potassium bicarbonate.

Midwest Specific Challenges: The moderate-to-hot heat and moderate-to-humid humidity of our Midwest summers can exacerbate problems like bolting and powdery mildew in Lemon Balm. Regular watering and good air circulation are key to keeping your plants healthy and productive.

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

Good companions include tomatoes, squash, broccoli, and cauliflower. Lemon Balm repels tomato hornworms and other pests that can damage tomatoes. It also helps deter squash bugs and squash vine borers, which are common problems for squash plants. For broccoli and cauliflower, it can help repel cabbage moths and other cabbage family pests.

I haven't found any specific bad companions for Lemon Balm.