Of all mints—more than two dozen species, and 100 cultivars—spearmint is best for general kitchen use: with peas, new potatoes and lamb, in drinks and desserts. Where peppermint would be too ‘hot’ and mentholated, and eau-de-cologne mint (as you’d expect) too perfumy, the mild flavour of spearmint complements without overpowering.
Mints run quickly from the root and are best grown in outlying parts of the garden and under shrubs, where their spread poses no threat.
Large containers, 30 centimetres or more in diameter, also serve to rein in roving roots. To make your own porous, moisture-holding potting mix, use one pail each of sandy soil, crumbly compost, peat moss or coconut coir, and either perlite or vermiculite, thoroughly mixed together in a wheelbarrow, with the addition of a palmful of lime and another of a natural fertilizer.
Planted in spring and faithfully watered, a small spearmint division or starter plant will fill its pot with roots in one season. In late fall, either bury the pot up to its rim in the garden or cover it over with bags of leaves. You could also pry out the mat of roots with a spading fork, lay it in a shallow hole and cover well with soil. Either way, come spring, as new green appears, start over with a lively division of six or eight shoots, potted up in fresh soil.