Last year I decided to put in a spearmint plant. Of course I'd heard all the tales about how invasive mints are and what drastic measures are needed to contain them. Serious gardening friend said he planted his mint in the middle of his lawn so that he could use the lawn mower to tame any offshoots or new growths. But still, I was determined. Perennial herbs are so tempting, and there was no way I was going to resist adding a nice mint to the collection.
So I did a little strategizing. The first thought was physical containment. I decided to sink a 5-gallon bucket into the ground, and plant inside that. So I cut off the bottom of the bucket, while my husband dug a fairly deep hole where I indicated. I had him put the dirt into a wheelbarrow, and to this I added a good amount of compost. The bucket was placed in the hole with a couple inches remaining above grade. Then I put in the soil and compost mixture until it completely filled the bucket, and backfilled the rest of the hole around the bucket. I knew the soil inside the bucket would settle down gradually over the season. I put my spearmint seedling in the bucket and watered.
My second thought was also physical containment. I'd been looking at this fragment of large plastic pipe that we'd fished out of a dumpster on a construction site for quite some time. Its diameter was several inches larger than that of the bucket, and laid on the ground it's about 10 inches high. Now mint is known to spread just by expanding its root system, which the sunk bucket should take care of. But it has a second, stealthy means of propagating itself. The plant can just grow a long stem which then casually, oh-so-innocently and when you're not looking because you're distracted by everything else going on in the garden, falls over under its own weight until it touches the ground. That's when this double agent piece of plant tissue grows roots and establishes a beach head. The plastic pipe was installed as a collar around the bucket to prevent exactly that habit. If the mint wanted to try spreading by such methods, the stem would have to grow very tall indeed, lean itself against the collar, and then droop a considerable way before reaching the earth. It never happened in all of last summer.
Interesting thing too about the bucket and collar system. I think it creates a microclimate that is beneficial in both summer and winter. Last summer was a scorcher - very hot and unusually dry for our area. I watered the mint seedling from planting through late spring, but it was mostly ignored after that. It held up fine through that sort of neglect, and I think the shade provided by the collar reduced the soil temperature at the surface inside the bucket, and therefore checked evaporation. The bushy habit of the mint also helped to cool its feet, I'm sure. In winter, the tall collar kept some wind off the plant, and the black color helped snow melt a bit faster and provided a little extra warmth in early spring.
This spring the level of soil in the bucket is at least a couple inches below the mulch I put between the outside of the bucket and the collar to keep weeds down. I see no signs of any offshoots from the spearmint. This is good, since I plan to add peppermint and catnip (another member of the mint family) this year too, though I fear we can count on the cats to help control the latter. I expect that the bucket and collar method will keep the spearmint from taking over the world in this second year which should bring even more exuberant growth. I'll be keeping my eye out for anything that can serve as collars for my additional mints when we go dumpster diving this year. If nothing turns up, we could cut out the sidewalls of some old tires and use just the tire rims.
How about you? Do you have any tricks for keeping the mint family within reasonable bounds? Or have they gotten the better of your garden?
I live on a 2/3 acre homestead in a residential neighborhood. A major goal is to demonstrate how much food a non-expert can produce in my particular climate and hardiness zone, with the soils native to my immediate area. We have gardens of annual and perennial plants, keep laying hens and honey bees, and regularly bite off more than we can chew. Another major goal is to pay off our mortgage as fast as possible. Here I blog about frugality, self-reliance, gardening, cooking and baking, food preservation, practical skills, half-baked experiments, and preparing to thrive in a lower-energy future.