Mint! For some, the word brings to mind fresh breath, refreshing drinks, or a place where money is printed. As a plant nerd, to me, mint means square stems. Here's why.
All mint plants are in the Lamiaceae family. Although not exclusive to this family, most mint stems are square rather than round or flat like other plants. Most are also quite aromatic. All mints have opposite leaf arrangement and two part (bilaterally symmetrical) flowers, which are quite lovely.
The mint family contains over 200 types of plants. Included are edible herbs such as mint, rosemary, sage, savory, marjoram, oregano, hyssop, thyme, basil, and lavender. It also includes plants grown for their ornamental features, such as bee balm, coleus, and salvia. Unfortunately, the mint family also contains a few evil cousins that we consider weeds, including Creeping Charlie, henbit, and deadnettle.
As you probably know, some mints are quite aggressive and can quickly take over a yard (or entire neighborhood). Anyone who has Creeping Charlie in their yard knows it creeps across the top of the ground, growing into new plants at each node along the aboveground stem (stolon). Similarly, true mints (Menta sp.) spread by underground stems (rhizomes) that also produce new plants along the way.
I like to grow mints to use in teas and other drinks. This year I purchased a Mojito Mint (Mentha x villosa). To contain their aggressive behavior, I always grow mints in containers placed on a hard surface. This prevents them from spreading in the garden or escaping through the bottom drainage hole. I can either overwinter the pot indoors or discard it and start the following spring anew.
Once invasive mints are established in the yard they are nearly impossible to eradicate. Pulling, mowing, or tilling them only cuts stems into pieces that produce new plants. Better control is often accomplished using herbicides. Tips for better control using herbicides is to spray in the spring or fall when the plant is actively growing, and use an herbicide containing a combination of ingredients (such as 2,4-D, MCPP, and dicamba) that is labeled for that use.
Be sure to cut and dry your edible herbs for use all winter long. Good air circulation is the key to successfully drying herbs. Sometimes drying is easier if the leaves are stripped from the stems and dried on screens or in food dehydrators. When dry, store the herbs in an airtight container and use regularly. Be sure not to use any pesticides on herbs you harvest to eat.
For more information on growing mints and other herbs, go to the the University of Illinois Extension "Herb Gardening" website at https://extension.illinois.edu/herbs, or call the Master Gardener Helpline at (309) 685-3140 Monday through Friday from 9:00 a.m. - 12:00 p.m.