How to Prevent Mint From Spreading

Many gardeners avoid growing mint due to its unfortunate habit of quickly outgrowing its space and invading the entire garden. Mint is a hardy, perennial herb that spreads by sending out vigorous rhizomes (underground stems). In order to keep mint under control, you need to prevent the rhizomes from spreading outside the mint’s allotted area. The easiest way to achieve this goal is to sink a container into your herb garden and grow the mint inside it. I use this technique in my garden and am able to grow five different types of mint! Here's how to do it.

Instructions

Difficulty: Moderately Easy

Things You’ll Need:

• 5-gallon plastic nursery container
• Potting soil

1. You will need one 5-gallon plastic nursery pot (the kind shrubs are sold in) for each variety of mint you’d like to grow. Most nurseries will happily give you these pots for free. I prefer the black plastic pots because they blend into the garden better than the green or reddish ones.
2. Mints’ roots can escape out the drainage holes in the bottom of the pot, so it’s best to cover the holes up with window screening. The screen allows water to drain out of the pot but prevents the rhizomes from growing through the drainage holes. For each pot, cut out two rounds of screen that are twice the diameter of your container. Place the two layers of window screen in the bottom of the pot, pressing the extra screen up the sides of the pot.
3. Choose a spot in your garden that gets at least five hours of sun a day. Dig a hole that is slightly wider than the nursery pot and about 2 inches shallower than the depth of the pot. Place the pot in the hole. You will want about a 2-inch lip of pot sticking up over the soil. This way, when the mint tries to grow over the edge of the pot you can easily snip off the stems before they have a chance to root in adjacent soil.
4. Fill the container with potting soil, making sure that the soil line inside the container is even with the soil line outside the container. Plant your mint in the center of the container and water it in well. Keep the soil inside the container evenly moist.
5. During the growing season, keep an eye on the mint and cut off any stems that attempt to escape the pot. You can place mulch around the pot to disguise it if you like.
6. Every two years, pull the container out of the garden and divide the mint to prevent it from becoming root-bound inside the pot. Replant a division in the pot by following Steps 1 to 4. Give extras away or dispose of them in a hot compost pile.