The green leaves of lemon balm have the scent of lemon with a hint of mint, with leaves that look like oversized mint — no surprise, since lemon balm is part of the mint family. Lemon balm can grow 24 to 36 inches tall and makes a nice green clump of medium-textured leaves among the other herbs and flowers in your garden. The plant looks best when it is cut back periodically, so plan to use lots of fresh, flavourful leaves to brew tea, flavour fruit or green salad, and season fish. Be sure to include stems in bouquets of summer flowers.
Soil, Planting, and Care
Growing lemon balm is a warm weather activity. After all danger of frost has past, set lemon balm plants 20 to 24 inches apart in rich soil where it will receive some shade during the day. Lemon balm will remain green during mild winters, such as those in zones 9 and 10. This plant responds well to cutting, growing back twice as thick. Whenever your plant is looking tired due to drought, hail, insects, or other stress, just cut it back and let it rejuvenate itself with fresh, new growth. Lemon balm likes rich, moist, but well-drained soil with a pH of 6 to 7. Because most people harvest it continually for lots of leaves, lemon balm needs a little fertilizer. When planting, add a coated, slow-release fertilizer such as 19-19-19 at the rate recommended on the label, or work plenty of organic nutrients from compost, blood meal, or cottonseed meal into the soil. Or, use Miracle-Gro® Shake ‘N Feed® Tomato, Fruits & Vegetables Plant Food when planting and then every couple of weeks thereafter.
Lemon balm does not spread by underground runners like mint. It will increase in size, though, making a bigger clump in the garden each season and sprouting from seeds that develop from inconspicuous flowers. To keep it from taking up too much of your garden, cut the plant back to a few inches tall several times during the growing season. This will keep the plant bushy and healthy-looking while preventing seeds from ripening. The flowers of lemon balm are not necessarily showy, but they will produce viable seeds that will germinate in your garden. Adding mulch will not only help prevent the fallen seeds from germinating, but the mulch will also slowly decay, feeding the soil with the rich organic matter that this plant needs.
Harvest and Storage
Lemon balm loses much of its flavour when dried, so it is a seasonal delight to be enjoyed while the weather is mild and the plant is green. However, enough of the fragrance remains when this herb is dried to make it a delightful addition to potpourri.
Like many other herbs, lemon balm can lose its flavour in cooking, so add it near the end of the cooking process. The fresh lemon fragrance and flavour go nicely with both chicken and fish dishes, as well as fruit and fruit juice drinks. Create your own herbal tea by cutting a few stems of lemon balm (plus any other appealing herbs), putting them in a pitcher, pour boiling water over them, and allow them to steep for about 15 minutes. Enjoy your tea hot or over ice.
Can I grow lemon balm in a pot?
Yes, lemon balm is one of the easiest herbs to grow in a container. It will flourish in a pot with rich, well-drained potting mix. Pots must be watered often, daily in the heat of summer. Frequent watering washes many nutrients out of the pot, so use a timed-release fertilizer or a liquid plant food (like Bonnie Herb & Vegetable Plant Food) occasionally when you water. Check the label to find out how often to apply.
I hear about plants that are lemon flavored. How does that happen?
There are actually quite a few herbs with a lemon flavor. How or why they have developed is a mystery. We do know that in times when lemons were not readily available in areas without hardy citrus, these plants added much to daily life. Lemon-flavored herbs include lemon balm, lemon basil, and lemon thyme.
My lemon balm looks pale and sick even after I fertilized it. What is going on?
Perhaps it is in too much sun. Many herbs do well in the sun, but lemon balm needs shade. Especially in areas in which the summer sun is hot, this plant grows best with some shade in the afternoon or in a spot where there are tall trees to lessen the intensity of the sun.
How can I keep lemon balm from taking over my garden?
Lemon balm will not take over like mint does, sending runners through the soil in all directions. The clump will gradually grow wider, however, and it will reseed in the garden. Pull up the seedlings around your mother plant, then mulch around the plant to prevent re-seeding. Frequent cutting will also keep lemon balm from blooming and developing mature seeds.