How Tall Does Lemon Balm Grow

If you’re planning to add lemon balm to your herb garden, one of the first questions you’ll have is how tall does lemon balm grow. Understanding its maximum height and spread is key to placing it correctly so it doesn’t overwhelm its neighbors.

Lemon balm is a vigorous perennial herb known for its fragrant, lemon-scented leaves. While it’s a wonderful plant for teas and pollinator gardens, it can get surprisingly large if left unchecked. Let’s look at the typical size you can expect and how to manage it for a healthy, attractive plant.

In optimal growing conditions, lemon balm typically reaches a mature height of 18 to 24 inches. However, its maximum height can sometimes exceed this range.

Under ideal circumstances—with rich soil, consistent moisture, and plenty of sun—it’s not uncommon for healthy clumps to grow up to 3 feet tall in a single season. The plant’s spread is often more impressive than its height, as it readily self-seeds and sends out runners.

Typical Size and Growth Habit

Lemon balm grows in a loose, somewhat sprawling mound. It’s not a tidy, upright plant like rosemary. Instead, its square stems (a hallmark of the mint family) branch out and can flop over as they get taller, especially after flowering.

Average Height: 1.5 to 2 feet (45–60 cm)
Maximum Height: 2.5 to 3 feet (75–90 cm) in ideal conditions
Average Spread: 2 to 3 feet (60–90 cm) per plant
Maximum Spread: It can colonize a much larger area via self-seeding if flower heads are not removed.

Factors That Influence Its Size

Several key factors will determine exactly how large your lemon balm gets each year. Paying attention to these can help you control its growth.

Sunlight Exposure

Lemon balm grows fastest and fullest in full sun to partial shade. In full sun (6+ hours), it will generally achieve its maximum height and produce the most oils in its leaves. In deeper shade, it will become leggy as it stretches for light and may not reach its full height potential.

Soil Quality and Fertility

This herb prefers rich, well-draining soil that retains some moisture. If you plant it in poor, sandy soil, it will stay smaller and less vigorous. Amending your garden bed with compost before planting gives it the nutrients it needs to reach its full size.

Watering Practices

Consistent moisture is crucial. Lemon balm likes soil that is kept evenly moist but not waterlogged. During hot, dry spells without adequate water, its growth will stall and it may become stressed, keeping it shorter.

Climate and Growing Zone

Lemon balm is hardy in USDA zones 3 through 7. In warmer climates (zones 8+), it sometimes behaves as a semi-evergreen. It puts on most of its vigorous growth in the spring and early summer, before the peak heat.

Managing the Spread of Lemon Balm

While the height is manageable, the spread is where lemon balm can become a garden thug if you’re not careful. It’s in the mint family, after all. Here are the best strategies to keep it in check.

Container Gardening: The absolute easiest method is to grow lemon balm in a pot. Use a container at least 12 inches wide and deep. This naturally contains the roots and prevents invasive spreading.
Use Root Barriers: If planting in the ground, sink a sturdy plastic or metal edging barrier at least 10 inches deep around the plant’s perimeter to stop runners.
Strategic Placement: Plant it in a bed bordered by pavement, a path, or a lawn that you mow regularly. The regular cutting at the edges will stop its advance.
Regular Harvesting and Pruning: Frequent harvesting of the tips for kitchen use encourages bushier growth and prevents flowering. This is the most pleasant form of control.

How to Control Height Through Pruning

You don’t have to let your lemon balm reach its maximum height. Pruning is a simple and effective way to maintain a shorter, bushier, and more productive plant.

Pinch Tips Early: When young stems are about 6 inches tall, pinch off the top set of leaves. This encourages side branching.
Cut Back for Harvest: You can cut stems back by up to half their length several times during the growing season. Always cut just above a set of leaves.
The “Haircut” Method: If the plant becomes tall and floppy, simply shear it back to about 6 inches tall. It will quickly regrow with fresh, tender leaves. Do this in early summer and you may get a second full crop.
Deadhead Religiously: As soon as you see flower buds forming, snip them off. This prevents self-seeding (controlling spread) and directs energy back into leaf production, which can limit excessive vertical growth.

Companion Planting with Lemon Balm’s Size in Mind

Because of its potential for both height and spread, careful companion planting is essential. You don’t want it shading out or smothering smaller herbs.

Good Companions: Plant it with other vigorous perennials that can hold their own, like bee balm, echinacea, or roses. Its flowers are excellent for attracting pollinators to your vegetable garden, so placing it near tomatoes or squash can be beneficial, just give it space.

Poor Companions: Avoid planting it right next to low-growing, delicate herbs like thyme, oregano, or creeping savory. It will quickly grow over them and compete for resources.

Seasonal Changes in Height

Lemon balm’s height isn’t static throughout the year. It’s a herbaceous perennial, meaning it dies back to the ground in winter in colder zones.

Spring: New shoots emerge from the roots and grow rapidly.
Early Summer: The plant reaches its pre-flowering peak height.
Mid-Summer: Flowering stems shoot up, adding extra height before the plant often looks a bit tired and leggy.
Late Summer/Fall: After a post-bloom cutback, it may produce a shorter, bushier flush of growth.
Winter: The above-ground growth turns brown and dies back. The plant’s energy is stored in its roots for next spring’s growth spurt.

FAQ: Lemon Balm Size and Care

Does lemon balm grow back every year?

Yes, lemon balm is a hardy perennial. In zones 3-7, it will die back in the fall and reliably regrow from its roots each spring.

How fast does lemon balm grow?

It grows quite quickly in the spring and early summer. From a small transplant, it can reach nearly its full height in a single growing season.

Can lemon balm be grown indoors?

Yes, but it will rarely reach its maximum height indoors. It tends to stay more compact in a pot on a sunny windowsill, usually maxing out around 12-18 inches with regular pruning.

How much space does a lemon balm plant need?

When planting multiple in the ground, space them 18 to 24 inches apart to account for their spread. Remember, they will fill in that space quickly.

Why is my lemon balm so tall and leggy?

This is usually caused by too little sunlight or a lack of pruning. The plant stretches toward the light and invests energy in height rather than bushiness. Move it to a sunnier spot or give it a hard prune.

Should I cut back lemon balm in the fall?

You can cut it back after it dies back from frost. Some gardeners prefer to leave the dead stems over winter to provide habitat for beneficial insects and then clear them away in early spring.

Knowing how tall does lemon balm grow and how wide it can spread empowers you to plant it wisely. With its typical height of 2 feet and potential for a 3-foot spread, a little planning goes a long way. By using containers, employing root barriers, and committing to regular pruning and harvesting, you can enjoy all the benefits of this fragrant, useful herb without letting it take over your garden. Its vigorous nature is a sign of health, and with simple management, it will be a delightful and long-lasting addition to your space.