Lemon Balm in Zone 8A — Pacific Northwest

Lemon Balm is a fantastic addition to any Pacific Northwest garden. Its citrusy, minty flavor brightens teas and dishes, and it's incredibly easy to grow in our mild summers and cool nights. Plus, the bees absolutely love it, which is always a bonus for the garden.

While our wet springs and relatively short bursts of real heat can present some challenges, Lemon Balm is pretty adaptable. With a 203-day growing season, you have plenty of time to get a good harvest.

Starting Lemon Balm indoors is an option, especially if you're eager for an early harvest. Begin in 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 warm – a heat mat can help speed things up.

Bottom watering is ideal to prevent damping off; just set the tray in a shallow dish of water and let the soil soak it up. Remember that our spring days can be pretty overcast, so supplemental light from a grow light will help ensure strong, healthy seedlings.

Transplant your Lemon Balm seedlings outdoors in early April through early May, once the danger of a hard frost has passed. Before you plant, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

Space your plants 18-24 inches apart in a sunny or partially shaded spot. Keep an eye on the weather forecast, as we can still get some chilly nights and wet spells during this time.

Direct sowing Lemon Balm is a simple and effective method, especially if you're not in a rush. Sow seeds directly into the garden in early April through early August. Choose a spot with well-drained soil and good sun exposure.

Gently press the seeds into the soil, keeping them about 18-24 inches apart. Keep the soil consistently moist until the seedlings emerge. Direct sowing is a little more hands-off, but you might have to thin the seedlings if too many sprout close together.

Lemon Balm appreciates moderate watering, especially during our dry summer months. While it's not as drought-tolerant as some other herbs, it also doesn't like to be waterlogged, which can be tricky with our wet springs. Aim for consistency without overdoing it.

During the spring, when we get plenty of rain, you might not need to water at all unless we have an unusually dry spell. Use the "finger test" – stick your finger about two inches into the soil; if it feels dry, it's time to water. In the peak of our mild summer, give your Lemon Balm about an inch of water per week, either from rainfall or irrigation.

Water at the base of the plant rather than overhead to prevent fungal diseases, which can sometimes be a problem even with our dry-summer humidity. Signs of underwatering include wilting or yellowing leaves, while overwatering can lead to root rot and yellowing leaves as well. A layer of mulch around the base of the plant can help retain moisture and suppress weeds.

Lemon Balm is relatively low-maintenance when it comes to pruning, but a little attention goes a long way. In midsummer, give the plant a haircut by cutting it back by about half to prevent it from becoming leggy. This encourages new growth and keeps the plant looking tidy.

Be sure to remove any flower stalks as they appear, unless you want the plant to self-seed (it can be aggressive!). As we approach our first frost around late October, you can give the plant a final trim.

You can start harvesting Lemon Balm leaves as soon as the plant is established, typically starting in mid June through early November. The leaves have the best flavor before the plant flowers, so keep an eye out for those flower stalks. Simply snip off the leaves you need with scissors or your fingers.

Harvesting regularly encourages the plant to produce more leaves, so don't be shy! Lemon Balm is best used fresh, as it tends to lose its flavor when dried. As the first frost approaches in late October, harvest any remaining leaves to use or preserve.

Here are a few common problems you might encounter with Lemon Balm in the Pacific Northwest:

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 self-seeds readily, and its roots can also spread. Our mild climate allows it to thrive and expand quickly.
• How to fix/prevent it: Remove flower stalks before they go to seed. Consider growing it in a container to limit its spread. Dig up and remove unwanted plants as they appear.

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. While we don't have extreme heat, even our mild summer can cause stress if the plant isn't properly watered.
• How to fix/prevent it: Keep the soil consistently moist, especially during dry spells. Provide some afternoon shade if possible. 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.
• What causes it: Powdery mildew thrives in warm days, cool nights, and moderate humidity. Even though our summers are dry, we can still get periods of humidity that favor its development.
• How to fix/prevent it: Improve air circulation by spacing plants adequately and pruning if needed. Remove affected leaves. Apply neem oil or potassium bicarbonate sprays. A milk spray (1 part milk to 9 parts water) can also be effective.

Pacific Northwest Specific Challenges: Our mild heat, combined with dry-summer conditions, means Lemon Balm generally thrives here. However, consistent watering is key to prevent bolting. Even though late blight is a concern for many crops in our region, it doesn't typically affect Lemon Balm. Keep an eye out for powdery mildew, though, especially during periods of higher humidity.

Lemon Balm makes a great companion plant for several vegetables in the Pacific Northwest garden. It's said to improve the growth and flavor of tomatoes and squash. Plus, its strong scent can help deter some pests that bother broccoli and cauliflower.

I wouldn't recommend planting it near anything that needs very dry soil, as Lemon Balm prefers consistent moisture.