Peppermint is a refreshing and stimulating herb. It is said to aid circulation and can be used to treat various digestive upsets.

Peppermint is a perennial ground cover that grows well in partial shade or in full sun. It is a summer-growing herb with upright, often purplish, square stems growing to one metre in height. It grows well in cool to temperate regions.

PROPAGATION

Peppermint grows well in most soil types, including heavy, moist soils – provided there is enough drainage, according to the South African Department of Agriculture, Forestry and Fisheries’ (DAFF) guidebook on peppermint production. The soil pH should be between 5.5 and 7.0.

Mint is an invasive plant and should rather be contained in a plant bed within a plastic edging to prevent it from spreading. It can also be grown in a container if it’s planted in well-composted soil and fed regularly with foliar food and an organic fertiliser.

Peppermint needs regular pruning to prevent its stems from getting straggly and woody. The herb is a gross feeder, but will perform well if a layer of manure is applied once a year and a dressing of organic fertiliser twice a year.

All commercial mint varieties are sterile hybrids and must be propagated vegetatively. This means that the plant has the ability to reproduce new plants from its stem or roots. Propagation is usually by the underground runners or rootstock from a nursery site. It is, however, possible to buy peppermint seedlings from nurseries.

COMMERCIAL PLANTING

The DAFF handbook advises that young shoots be planted at 40 cm to 90 cm between rows and 15 cm to 45 cm within rows, and lightly covered with soil. At this density, growers will have 55 000 to 75 000 plants per ha and the soil will cover over quickly.

Apply fertiliser before planting if a soil sample indicates levels lower than what is recommended. About 120 kg phosphorus and 500 kg potassium should be available per hectare. Frequent nitrogen applications are required throughout the growing season to maintain soil fertility.

Peppermint needs frequent irrigation to supplement rainfall. Well-established plants should be watered at least three times a week. Peppermint will grow under flood and sprinkler irrigation.

WEEDS AND DISEASES

Weeds compete with peppermint for available nutrients, thereby reducing yields. They should therefore be removed manually or be managed with a suitable herbicide.

Peppermint is vulnerable to cutworms, loopers, mites, weevils, aphids, grasshoppers and soil nematodes. If you have older mint stock, be extra careful of pests such as nematodes.

Peppermint is also susceptible to several diseases such as rust, verticillium wilt, leaf spot diseases and anthracnose.

COMPANION PLANTING

Peppermint is an excellent companion plant, as it attracts bees and other beneficial insects. It repels ants, aphids, cabbage fly and flea beetles.

The herb enhances crops such as cabbage, broccoli and other kales, if planted nearby. Avoid planting peppermint near chamomile and parsley.

• This article was written by Wilma den Hartigh and first appeared in Farming SA.