How to Prevent Mint From Spreading and Taking Over


Catmint and Spearmint

Peppermint, spearmint, lemon mint (lemon balm), chocolate mint, horse mint, catmint and similar kinds of mint are easy to grow and are very good aromatic additions to the garden or flowerbeds. They do have a drawback, however. Mints tend to be invasive. If steps aren’t taken to prevent it from happening, mint can take over the flowerbed or garden. These plants can be grown in pots, however there is also a way to keep it from spreading out and taking over when it is planted outside.

Perhaps no mint is better known for its propensity to spread than peppermint. However, all members of the mint family will spread if the conditions are right. Some species, such as sage, thyme, basil and anise sage spread primarily by seeding themselves. To keep these from spreading, simply remove the blossoms before the seeds have a chance to form. Peppermint, spearmint, lemon mint, catmint and others spread primarily in a different way, however. We’ll use peppermint as a representative example.

Mint rhizomes

As a peppermint plant grows, it begins to put out underground rhizomes. These roots are usually one to three inches deep and run generally parallel to the surface. They can also grow over two feet in length. From the rhizome, new plants can emerge periodically and once they break the surface, they become self-sufficient plants, which can in turn produce more rhizomes. Many people with lawns are aware of this principle because this is exactly how crab-grass spreads. The rhizomes are actually a survival mechanism because as hardy as mint is, eradicating it is extremely difficult. If you try to get rid of the plant and leave just a bit of the rhizome that has a plant node on it, the mint will continue to grow. The key, then, is to prevent the rhizomes from spreading to begin with.

Blocking rhizome spread

To contain the mint, start by digging up the area you want to have the mint growing in. Remove the dirt to a depth of at least a foot. This also gives you the chance to mix finished compost in with the soil before using it again. Mint isn’t picky about having rich soil and will grow in quite poor soil, but if compost is mixed in, you should be able to have a sustainable mint crop for years.

Once the dirt is removed, line the hole with two layers of black plastic, making sure that it is weighted down. Put the dirt back into the place the mint is going to be planted, then plant the mint a few inches apart and water the mint well. It might not seem like there isn’t much mint there at first, but it shouldn’t take long for it to fill out the patch. A patch that is two feet wide and four feet long is likely to produce all the mint the average family is likely to use.

How it works

How the black plastic prevents the spread of the mint is simple. The plastic prevents the rhizomes from going beyond the sides of the patch, forcing them to turn inward. This helps the plants to fill out the mint patch rapidly, while slowing down the invasive nature of the mint. This isn’t a long term solution, because the black plastic will eventually decay, allowing the rhizomes through. It might sound like a lot of effort for something that is only going to work for a year or two, but really it isn’t. If the roots are permanently contained, within a couple of years the plants can become root-bound and the growth will become stunted. The plants can even die. This happens in pots, too. This means that every couple of years (more often with pots), the mint should be dug up, separated and replanted. That is the perfect time to replace the black plastic. It is also a great time to make sure that there are no persistent weeds and grass growing in the mint patch.

By using the black plastic, the mint can be prevented from spreading and being invasive. By maintaining the patch and doing the separating and replanting every couple of years, the patch remains vibrant, healthy and wonderfully scented. It does require a little effort, however the aroma and the taste of the mint makes it all worthwhile. After the work, you even have a great excuse to make yourself a steaming cup of mint tea. If the weather is too hot, there is no problem, either. Instead of tea, how about an ice cold glass of mint julep? In fact, you can even add a few leaves to a tall glass of iced tea.



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Posted in food and plants and tagged , , , , , , , , by with 18 comments.


  • Fifi Leigh says:

    i want to grow my own mint. how do i grow mint in a pot…

  • rextrulove says:

    @fifileigh, I can write something for more detail, but you first need a pot that is about 12 inches in diameter and about that deep. Then you need to decide if you want to plant from seeds, cuttings or seedlings. The biggest mistake people make with growing mint in pots is to use a pot that is too small. There needs to be room for the roots and rhizomes.

    • Fifi Leigh says:

      i bought some mint leaves from grocery store. should i put one in the dirt, sticking out and water it…

      • rextrulove says:

        @fifileigh, you could try that, but it probably won’t be successful. What you need is a stem that is about six inches long, that has several leaves on it. Take off the leaves from the bottom half of the stem and put it in a clear glass or jar of water, then put it in a sunny place. It should start to root in a week or so.

        Alternately, you could just buy a mint seedling at a gardening store. Usually they aren’t all that expensive and once it is growing well, you can make as many starts as you want. I do this with basil and sage, too. The advantage of starting with a seedling is that you can get exactly the kind of mint you want without having to rely on what a grocery store produce section has available.

  • wolfgirl569 says:

    That is a great way to put it in the ground, I plan on just growing it in stacked tires or planting a large pot in the ground. Read an easy way to do that. You put an empty pot in then use one that will just set inside that one so you can pull it out easy to work with the plants.

    • rextrulove says:

      @wolfgirl569, you could do it that way and if the inner pot was enough smaller, you could put sphagnum moss between the pots. It covers the inner pot and is so light, drying out easily, that any rhizomes would stop there.

  • Mark Graham says:

    I grew spearmint and peppermint and they always grew like weeds. Love them.

    • rextrulove says:

      @marky2016, I still grow them. Currently, we have peppermint, spearmint, chocolate mint, cat mint and I plan on planting pineapple mint. I have mint growing in several locations. I also have oregano, sage and thyme growing in several locations. 🙂 My thyme is in bloom and the sage is getting ready to bloom.

  • Andria Perry says:

    I have spearmint and its gone wild by the front steps and I love the smell, I will let it thrive for a while, right now anyways.

  • Nana says:

    I have mint growing also started three years ago

    • rextrulove says:

      @nana, a couple days ago, I took a cutting of peppermint, spearmint and cat mint so I can propagate it. I’m not done planting mint around here. 🙂 Our little plant store has orange mint…I’ve never heard of it and I’m thinking of growing some.

  • Fifi Leigh says:

    if i can find one. my townhome association used to have lots of mint in the area because i used to walking around and see it all over the place. but i dont see it anymore. maybe they destroyed it.

  • That makes sense. Thanks so much! It’s unreal how the roots spread and new plants pop up feet away.

    • rextrulove says:

      Indeed it is, @kimdalessandro. Around here, we have a lot of bindweed (wild morning glory) and crabgrass that is the same way. It isn’t all that hard to contain it, but people often don’t even think about it when they plant it. It is only when it is coming up all over the place that they realize that they should have taken steps to contain it. LOL

  • Fifi Leigh says:

    maybe i will check a plant store in the future, but with my luck, i will probably end up killing it anyway. i am not good with any plant.

    • rextrulove says:

      @fifileigh, I wrote an article today about how to grow mint in pots. In that article, I included how to start mint from seed, so you could try it that way. You’d only need a packet of seeds. Once it is growing well, it is really difficult to kill, unless you water it so much that the roots are standing in water, or don’t water it at all. 🙂 Those are two extremes that most people won’t do.

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