Mint is a prolific grower that must be tended to prevent it from encroaching on neighboring plantings. In most turf wars between mint and other plants, mint wins.
Recognizing this, many gardeners plant mint in containers.
The goal for any container crop is full, healthy plantings and high yields. In the case of mint you'll want your plants to be as bushy as possible so that you will be able to harvest all the fresh leaves you want for cooking, medicinal uses, aromatherapy and whatever other purpose your imagination and research suggests.
Pinch and Clip to a Fuller Pot
Fertilize your mint once in the spring with a commercial liquid fertilizer, such as fish emulsion. Dilute the fertilizer to half the strength recommended on the package. Mint that is over-fertilized tastes bitter. Do not fertilize again unless plants appear leggy in mid-summer.
Place the container in a sunny location. Mint does best in full sun.
Pinch regularly looking for pairs of tender new leaves at the tip of each stem. As the plant grows larger, you won't get them all. Don't worry, just continue to pinch back on a regular schedule. This will encourage lateral growth, including extra branching and leaf production along each pinched-back stem.
Harvest your mint often. Try to harvest sprigs about 3 to 4 inches long from all over the plant in order to help the plant maintain a pleasant symmetrical shape. This will also encourage vigorous lateral growth. Let the center of the plant grow a little taller than the edges for a nice domed effect. This will have the added benefit of allowing sunlight to reach more of the leaves.
Harvest more aggressively, removing up to two-thirds of the plant's mass, as fall approaches and the growing season comes to an end, Your mint will come back even stronger in the spring.
Water your plant often during the growing season. In winter, water occasionally.
Protect your mint from the winter cold. Mint is a perennial plant that will come back in the spring stronger than ever if you give it a modest amount of protection during the winter. Several methods will do. After you have harvested for the last time, mulch the mint with dried leaves or straw and cover with a plastic garbage bag. Secure the bag with packing tape, hemp, or twine. Alternatively, move the pot to an enclosed space, such as a garage where it will receive moderate light and allow it to remain uncovered. Finally, move the container indoors.