If you enjoy growing herbs in your garden, you may have discovered that your mint, in particular, has a nasty habit of taking over a significant portion of your yard. Thankfully, there are several ways to plant mint while also keeping it contained.
You can keep your mint plants from spreading by planting them inside different types of containers where they won’t be able to expand. You can also keep your mint plants from spreading by planting them in a designated space or with barriers surrounding them to keep them from spreading.
This article will discuss some tactics you can try to keep your mint from spreading into areas of your garden where you do not want it, as well as why it spreads as much as it does. If you want to contain your mint while still receiving a healthy harvest, then stick around.
1. Container Placed on the Ground
When planting mint, the primary goal is to set it up so that the roots aren’t able to spread out throughout the soil and shoot up in other areas of the garden. One way this can be done is to plant the mint in a container before putting it into the soil.
It’s not common for a plant to be placed in both a container and the ground. Usually, it’s planted in one or the other. However, because mint can develop and move throughout the soil so quickly, it might be necessary for the plant to be more contained.
To plant mint in a container in the ground, do the following:
- Add soil into the pot and place the mint plant into the soil.
- Dig a space in the ground that’s deep enough to hold the pot containing the mint.
- Place the pot into the ground and surround it with the remaining soil.
You’ll want to leave 2-3 inches (5.08-7.62 cm) of the pot sticking up above the earth so that the mint cannot escape the pot and send roots into the ground.
Keep an eye on the mint and trim it back if it spreads over the top of the container. If the mint can escape, it can trail along the ground, set down roots under the earth, and spread in that manner.
If you decide to try this method, it’s best to use a plastic pot that has drainage holes in the sides, so the soil inside the pot does not become too saturated with water. If your pot has drainage holes, you’ll need to give the pot a quarter turn in the ground every week, so the roots aren’t able to run out of the holes and into the ground.
It’s preferable to use plastic instead of clay because it will be easier to turn in the soil. A plastic pot will also not dry out as quickly as clay would when buried in the earth.
2. Container Placed on a Hard Surface
If you want to keep your mint contained but prefer not to put a pot in the ground to hold it in place, another option is to grow the mint in a planter sitting on a hard surface.
You can use any type of pot for this method if it has some drainage holes in the sides or bottom to let out any excess water. Just place the mint in the planter, cover it with soil, and then set the planter on your deck or patio.
You can also get creative with this method and make your garden look stylish at the same time by purchasing large stone slabs to set the mint containers on while they grow. As long as the mint rhizomes cannot touch the ground directly, any hard surface will work.
3. Bottomless Containers
If you want to plant your mint in the ground without using a whole pot, you can grow your mint in bottomless containers. To do this, you will need to find some sort of tube with an opening at both the bottom and top. PVC pipes are an example that can work very well for this method.
When you’re planting the mint:
- Dig a space in the earth large enough and deep enough to contain a section of PVC pipe or another tube.
- Place the PVC pipe tube in the ground and fill it halfway with soil.
- Put the mint seedling in the center of the tube and cover the rest of it with soil, leaving about 1 inch (2.54 cm) of pipe up above the ground.
It’s essential to leave a bit of the tube outside of the soil so the mint is kept away from the ground and does not attempt to spread.
The bottomless aspect of the container means that the roots will still be able to grow deep into the earth, but the underground and above-ground runners remain contained and unable to expand.
Another benefit of using bottomless containers is that it’s much easier for excess water to drain. If mint becomes too saturated with water, it can wilt and even die, so having tubes through which water can pass easily is a benefit.
4. Partially Open Containers
Partially open containers have openings in several spots, much like a strawberry jar, which is designed to allow strawberries out of the side holes. Planting your mint in a strawberry jar can keep it from spreading while giving it some space to grow properly.
The most significant benefit of using a strawberry jar is there are no drainage holes on the bottom. Because of this, the roots won’t be able to flow out of the base and spread throughout the garden. And if you need to replant them elsewhere, you can easily pull the pots out of the ground without causing distress to your mint plants.
There are enough holes in the lower portion of the container that water can still flow through without the soil becoming too soaked.
But the roots won’t be able to escape and overtake the rest of your developing plants.
5. Fabric Bags
You might choose to plant your mint in fabric bags specifically designed for planting in your garden. They are made from a geo-textile fabric that doesn’t have large holes in it for the mint rhizomes to escape from but is porous enough to keep the soil from becoming too waterlogged and for air to flow through.
To plant your mint inside a fabric bag:
- Dig a hole in the ground deep enough for the fabric bag to fit without being too bunched up.
- Place the bag in the soil, keeping the top of it 3 inches (7.62 cm) above the ground.
- Fill the bag with soil and place the mint seedling inside, packing the dirt around it.
If you decide to use this method, keep an eye on the mint plants to ensure the roots aren’t growing up over the edges. If they do, the plants are much more likely to spread throughout the rest of your yard or garden.
6. Dig the Mint and Divide It Up
If you’ve decided that you don’t want to plant your mint in a pot, planter, or another container, there are still a few ways to slow down or halt the spread of its rhizomes.
One such method is to dig up and replant your mint when it starts to develop outside of its designated space in the garden. To do this, keep a watchful eye on your mint as it sprouts out of the ground and continues to develop.
When you notice that the roots are attempting to crawl outside of their plot in your yard, you’ll need to dig up the plants. Pulling up the entire mint plant, including the massive clump of roots that have likely formed, can be a bit of a challenge, so you’ll need to do your best to ensure that you have pulled the entire plant out of the ground.
Once you’ve dug up the mint, separate the massive plant into smaller sections and replant those sections 1 to 2 feet (0.3 to 0.6 m) apart from each other. Keeping them that far apart will make it more challenging for them to become prominent.
An additional benefit to using this method of dividing the mint into smaller sections is that it keeps the plant from growing too scraggly.
If you let mint spread too much, the stems start to become woody, and the leaves can become a tangled mess on the ground. When you dig up and divide up the plant, it becomes much easier to manage, not to mention it will grow healthier, too.
7. Plant the Mint Along Your Garden Borders
You could also plant the mint along the borders of your garden so that it can use the garden’s barriers to stop its spread. Your mint seedlings will do better if you plant them in an area where they can naturally grow without much work from you.
Letting mint develop along the barriers of your garden means that it can still spread along the sides of the area, but it won’t be able to take over the soil where other plants are located.
If you decide to use this method, it’s still crucial to dig up and thin the plants by dividing them into sections. Otherwise, they can become too dense, the stems can grow woody, and the mint can die.
8. Put Barriers Around the Mint
Letting mint plants spread up rather than out is another way to keep them from taking over the rest of your yard. The easiest way to ensure they will grow upward is to put barriers around the plants.
Setting up wire fencing or a wooden trellis can encourage the mint plants to grow along the posts, especially if they don’t have much access to the soil around them. With a barrier in the way preventing the roots from spreading, the mint will have no other choice but to climb up.
If you use this method, you’ll need to prune the mint plants regularly to prevent them from straying outside of the barriers. Using garden shears, remove any stems that are starting to attempt to crawl under or between the fence.
Trimming the excess bits off the plant will keep it where it’s supposed to be rather than allow it to spread out to other garden areas. If you use garden shears for any of the methods on this list, you should sterilize them after pruning your mint plants.
Mint is highly prone to powdery mildew, a type of fungal disease. If you use the shears on another plant after trimming the infected mint, the fungus can potentially spread throughout your garden and destroy your other crops.
9. Keep the Soil Dry
The final step to keep your mint plants from spreading is to keep the soil in which they are developing dry and free from excess moisture.
Typically, herbs, vegetables, and other plants that are grown in a garden can only thrive when they develop in soil that’s moist and nutrient-rich and will struggle if the earth becomes too dry. Mint, on the other hand, is so resilient that it can grow in almost any soil or weather condition.
If you plant your mint seedlings in dry soil, the environment won’t be as inviting as it would be if the soil were moist and full of nutrients, but they will still be able to grow. You’ll be able to benefit from the delicious herbs that the plants produce, but they won’t be able to grow as quickly or as much, helping you keep spreading to a minimum.
Why Does Mint Spread So Much?
Mint plants have extraordinarily sturdy roots, also known as rhizomes. Once the mint has been planted, its rhizomes begin to grow more resilient and turn into large, tough stems under the soil’s surface.
They then form lateral shoots so that runners are growing both above and underground, which, in turn, causes additional mint plants to develop outside of their designated plot of land.
These roots have the potential to form massive clumps, ensuring that the mint plants cannot be easily removed from the ground. And even if you attempt to pull them out completely, tiny bits of the roots will likely remain firmly in the soil, allowing new mint plants to form.
The fact that the roots can become so big also means that they can easily overtake the other plants in your garden and push them out of their growing space. Then, just like when weeds sprout up around everything growing in your garden, the mint will begin to take the nutrients away from your other plants and can end up hurting them.
If you’re growing multiple kinds of mint plants, they can even begin to overtake each other and end up interbreeding, leaving you with hybrid herbs with an unappealing flavor.
Additionally, mint has the ability to grow and thrive in many types of climates and conditions. The plant has the power to survive, whether it’s developing in complete shade or direct sunlight. If left to grow in hot, intense sunlight with little to no shade, the mint has the potential to wilt and go brown.
And if given enough water and room to move, mint will expand drastically regardless of its growing conditions.
How Fast Can Mint Spread?
If mint rhizomes have the opportunity to spread throughout the garden, they will take it. But how quickly are they able to overpower your other plants?
While the speed at which mint can spread depends largely on its variety, most mint plants can grow up to 4 inches (10.16 cm) in a month. If planted in the ground with no barriers surrounding it, one mint seedling could reach about 2 feet (0.6 m) in length within approximately 6 months.
In addition to that singular plant spreading throughout the area it is designated to, more new plants can pop up from the ground as the roots branch out and grow stronger. If not properly restrained, mint has the potential to completely overrun the rest of the plants in your garden.
Spearmint is the species that can grow the fastest because it’s the strongest of the mint plants by far, but the other varieties of mint are also capable of causing quite a bit of damage. While peppermint does not spread as quickly, it is still very invasive and will grow about 2 -3 inches (5.08 to 7.62 cm) per month.
Whether you decide to plant your mint in some sort of container that prevents the roots from escaping or simply watch and prune it to ensure it does not expand outside of its boundaries, keeping your mint from spreading takes some work but is well worth it in the end.