Why Your Mint Is Tall and Leggy – 5 Reasons & What To Do

If you are growing mint in your garden or in a container, you may notice that the plant’s productivity is decreasing and its stems are becoming longer.

Legginess is when the stems grow tall and lose many of the leaves except for a tuft of leaves at the very top of the stems. It’s not a good sight nor does it promote an abundance of leaves. Something has to be done. 

Mint requires full sunlight, moderate fertilizing, and warm temperatures. If it doesn’t get 8 hours of light, it will grow tall as the plant extends its stems in search of light. Over-fertilizing and cold temperatures can also make it leggy. If potted mint is rootbound, the stems will grow tall and bare.

Knowing which growing conditions help mint plants grow bushy and healthy will help you avoid leggy mint.

Read more to find out what causes this issue and what you can do to remedy the situation.

Causes of Leggy Mint (With Solutions)

When your mind grows tall and leggy, that usually indicates a problem with the growing conditions.

The most likely culprits are lack of sunlight, cold temperatures, and over-fertilizing, but it could also mean that a potted mint is rootbound and in need of a larger pot.

1. Insufficient Sunlight

As a sun-loving herb, mint needs between 6 and 8 hours of direct sunlight to grow healthy and thrive.

If a taller plant is casting shade on the mint, the herb will grow taller stems as it searches for sunlight. The taller stems lose their leaves and become leggy.

What To Do

Make sure that the mint plant is getting enough sunlight every day. Remove any obstacles that block light from the herb. If it’s potted, move the pot to a window sill facing the west or south. 

2. Lack of Pruning

Like other perennials with moderate to fast growth rates, mint tends to get messy and unshapely if left to its own devices.

Since the plant cannot support all the leaves on the tall stems, many leaves will drop and only a few leaves near the tip of each stem might remain. You’ll need to step in with your trusty pruning shears.

What To Do

When pruning your mint, make sure to make the cut just above the node. This will trigger new growth that gives the herb a bushy look. Out of each node, two stems come out.

Prune the herb in the summer after it has flowered and whenever it gets leggy.

3. Plant Is Rootbound

Potted mint tends to get rootbound if you don’t repot it regularly. When the roots run out of space to grow and soil from which to pull nutrients and moisture, the plant will grow vertically, shed its leaves, and look unwell.

One sign to look for is when the roots come out of the drainage holes in the pot or are visible on top of the soil.

What To Do

The only solution to a rootbound mint is to repot it. Choose a large pot with plenty of drainage holes at the bottom. Fill it with a general-purpose potting mix and replant the mint in it.

Top off the pot with organic compost (if you don’t make your own, you can find it here), and water the plant immediately.

4. Too Much Fertilizer

One common mistake gardeners often make is to give their mint too much fertilizer. Fast-release fertilizers cause a growth spurt that the herb cannot handle.

While the stems and leaves are growing above average, the root system is still underdeveloped. The plant cannot support this extra foliage and has to get rid of many leaves. This leads to leggy mint.

What To Do

Avoid fast-release and chemical fertilizers that could strain the herb. If you see the plant getting leggy, abstain from fertilizing it, and flush the excess nutrients from the soil by watering thoroughly.

Prune the tall stems to promote a bushy look and conserve the plant’s energy until its root system develops more fully.

5. Plant Was Allowed To Flower

Once mint flowers, it will focus its resources on developing flowers and seeds at the cost of growing leaves. Unfortunately, there’s no reversing this process, especially when the flowers have opened.

What To Do

Cut the flower buds as soon as they develop. If the flowers have opened, cut them, and prune the stems carrying those flowers.

This will refocus the mint back on producing full foliage instead of growing flowers and seeds.

A close look at a large patch of healthy garden mint.

When To Prune Mint

You should prune mint whenever you notice its stems getting leggy and the plant shedding its leaves. This often happens when the plant is ready to flower.

The best time to prune mint is in the late summer, but you can also prune it any time it grows out of shape for any of the reasons mentioned above. 

How To Prune Mint

When it comes to pruning mint, less is more. Your goal is not to cut back the plant but to trim it lightly and remove any overgrown or leggy stems.

When cutting a stem, aim for just above the node to make a cut. The node will then grow two stems to replace the one you cut. This promotes bushy growth and avoids the leggy and shabby look.

Don’t cut more than one-third of the stems carrying leaves at a time. If you need to prune more stems, give the plant a few weeks of rest between prunings.

How Often To Prune Mint

You should prune mint whenever the occasion rises. As long as the plant is getting enough sun and is not rootbound, you shouldn’t have a problem with that leggy appearance. In that case, pruning it once in the summer is enough. 

If you are harvesting stems routinely for kitchen use, you may not ever need to do additional pruning.

Closing Thoughts

When mint grows tall and leggy, this implies that the plant is having problems with lack of sunlight, over-fertilizing, or being rootbound if it’s potted.

Fixing the problem will help the mint regain its youthful and bushy look. Prune the leggy stems, and avoid fertilizing it for a while.