Mint in the Garden
Mint is a rapid growing perennial herb with many varieties that grow up to 3 feet tall and are quite invasive. Mint grows best in full sun to partial shade, should be planted early in the growing season and is generally hardy to -20° F. Mint prefers moist soil conditions, but excess water will promote root and leaf diseases. Harvest leaves and stems throughout the season, or cut back within an inch of the ground about three times a season, just before the plant blooms.
Use care when selecting mint varieties. The taste and smell varies greatly between varieties. For cold areas of Utah, peppermint, spearmint, and woolly mints are very hardy. All varieties are well suited to areas of Utah with more mild winters. Culinary varieties include those listed above and those with mint-like flavors including red raripila mint, ginger mint (redmint), horsemint, and pineapple mint. Mints widely used in teas and medicinal preparations include watermint, corn or field mint, and pennyroyal.
How to Grow
Mint prefers rich, moist and slightly acidic soils and grows best in full sun or partial shade. Most soils in Utah are suited to mint provided they are amended with compost. If growing a variegated variety (pineapple mint), full sun may scorch the leaves.
Before planting, determine fertilizer needs with a soil test and then follow the fertilization recommendations given. If fertilizer are needed, work the fertilizer into the top 6 inches of soil. If you fertilize with compost, apply no more than 1 inch of well-composted organic matter per 100 square feet of garden area.
Mint can be grown from seed or transplants. Since mints readily hybridize between different types, plants grown from seed often fail to be true to type. For specific cultivars or varieties, buy established plants from reputable sources, take cuttings from known plants, or divide an established plant. Divide and replant established plants in the spring before growth starts or early in the fall.
Planting and Spacing
Sow seeds ¼ inch deep and then thin seedlings once they emerge. Transplants should be planted with roots just beneath the soil surface. Row spacing should be at least 2 feet apart to allow for growth.
Water regularly during the growing season, supplying up to 1 to 2 inches per week, depending on temperatures, exposure and soil conditions. Avoid overwatering as it leads to disease.
One early spring application of a slow release, complete fertilizer incorporated into the soil will supply adequate nutrients for mint. Use one teaspoon of a 16-16-16 fertilizer per plant as growth resumes in the spring. Over watering and fertilizing promotes rust and diminishes mint oil production.
Mint is best planted in containers or where roots are confined. Mint spreads quickly in open garden areas and will out-compete most garden plants. Once established it is very hard to eradicate.
Pests and Disease
Most diseases can be minimized or eliminated by appropriate watering and ensuring proper sunlight to plants. Consider drip irrigation as an excellent method to provide regular water and keep foliage dry. As the mint grows and multiplies, thinning or dividing may be essential to maintain healthy plants.
|Aphids||Green or black soft-bodied insects that feed on leaves. Foliage curls, yellows or becomes stunted.||Use insecticidal soaps, registered insecticides or spray plant with a forceful jet of water to dislodge the insects.|
|Flea Beetle||Small, shiny black beetles that chew tiny holes in leaves.||Control with registered insecticides or cover plants in spring with row covers.|
|Cutworm||Larvae feed at or below ground and sever stems of seedlings or plants.||Protect individual plants with a collar or trap, use registered insecticides.|
|Anthracnose||Small water soaked spots on leaves and stems.||Rotate planting areas, remove diseased plants, and prune healthy plants to the ground in fall.|
|Mint Rust||Small whitish, slightly raised spots that turn reddish orange or brown on underside of leaves.||Avoid wet leaves overnight. Use drip irrigation or apply overhead water before mid-day.|
|Verticillium Wilt||Leaf yellowing starting at the margin and they eventually curl up and die.||Rotate planting areas, remove infected plants, and do not over fertilize plants.|
Harvesting and Storage
Fresh leaves may be harvest throughout the growing season once plants are 3-4 inches tall. Use a sharp knife or scissors to remove leaves and stems. The youngest leaves and stems are the most flavorful. Cut the stems to within 1 inch of the soil, picking late in the morning on dry and sunny days. Fresh mint may be stored for a week in water in the refrigerator.
Harvest fully grown stems and leaves and hang the cuttings upside down in a hot shady location until brittle, or spread on a screen in the shade to dry. Store dried mint in an airtight container for up to 1 year.
Individual leaves do not freeze well. To maintain taste when thawed, freeze chopped mint leaves with water in an ice cube tray.
One or two plants will supply sufficient fresh cuttings for daily use. Several additional plants will provide for drying and storing. Each plant can be harvested two to three times per season.
Mint is high in fiber, iron, vitamins A and B6, folate, calcium, magnesium and manganese. A serving of dried mint will be significantly higher in nutritional values than fresh mint.
Frequently Asked Questions
Q. How can I stop the mint from taking over my garden? Prior planning is important before planting mint. Consider separate beds or grow mint in buried containers to contain the spreading rhizomes. Containers should extend 3-4 inches above and 10-15 inches below the soil surface to ensure containment.
Q. Should I allow the mint to bloom and how should I prune? If allowed to bloom, the oil content in the leaves decreases and is less flavorful. Pinch the blossoms back as they show or simply cut back the plants to within 1 inch of the soil two to three times a year. It is very difficult to over-prune a mint plant. Before winter, cut each plant back to the ground to discourage pests and diseases.
Arkin, Frieda. The Essential Kitchen Gardener. New York:Holt, 1990.
Ball, Jeff. Rodale’s Garden Problem Solver. New York:Rodale, 1988.
Bown, Deni. Encyclopedia of Herbs and Their Uses. New York: Houghton Mifflin, 1995.
Stuart, Malcolm.The Encyclopedia of Herbs and Herbalism. New York: Crescent Books, 1981.
Published May 2020
Utah State University Extension
Peer-reviewed fact sheet
Kristie Buckland and Dan Drost Vegetable Specialist