Mint

Mint grows wild across Europe, Asia and Africa in damp ground, along ditches and stream banks, spreading by underground runners that travel a surprising distance in a season. Everything useful and everything troublesome about it comes from that. It is almost impossible to kill, it wants more water than any other common herb, and if you put it in a border it will be there for years after you change your mind. Grown in a pot and cut hard, it is one of the most productive things on a kitchen windowsill.

Where to plant it

In a container, always, unless you genuinely want a bed of mint and nothing else. The runners spread just below the surface and root as they go, and a single plant covers several square metres in two or three seasons. Pulling it out leaves fragments behind, and every fragment is a new plant.

If you want it in the ground, sink a bottomless bucket or a large pot into the bed with its rim standing two or three centimetres proud, and plant into that. The rim stops the runners going over the top, which they will otherwise do.

Light

Part shade to full sun. In a cool temperate garden full sun is fine. In a hot climate, afternoon shade gives noticeably larger, more tender leaves, and a plant in baking sun goes small leaved and tough.

Water

Keep the compost damp at all times through the growing season, which in warm weather means watering every two or three days. This is the one plant in this journal where standing the pot in a saucer of water through high summer is good advice rather than bad. In winter, with the plant dormant or slow, water about every ten days and never let it sit cold and sodden.

A mint that dries out completely sheds its lower leaves immediately and takes weeks to look right again.

Sowing and planting

Sow in late spring, April to June in the northern hemisphere and September to November in the southern, once the soil is warm. Seed raised spearmint is variable and slow, and most gardeners never bother.

Division is quicker and gives you a known plant. In spring, tip a pot out or lift a clump, pull off a few rooted runners, and pot them individually. A cut stem stood in a glass of water roots at the node within about a week, which is the easiest propagation of any herb here.

Harvesting and keeping it going

Cut whole stems rather than picking individual leaves, taking them from the outside of the clump, from May to October in the north and October to March in the south. The plant branches from every cut, so regular harvesting keeps it dense.

Cut the flowering stems out as soon as they show. Once mint flowers, the leaves turn tough and the flavour coarsens. When the whole plant starts to look tired and woody in the middle, usually by midsummer, cut it right down to about five centimetres. It regrows completely within three weeks and the new growth is the best of the year.

Divide and repot every spring. A pot of mint exhausts itself within a year, and the difference between a first year plant and a third year one is obvious in the leaf.

Ailments

Mint rust, which shows as bright orange pustules on the leaf undersides, is the one serious disease. Cut the plant to the ground, bin the material rather than composting it, and do not propagate from an affected plant. Powdery mildew follows dry roots and crowded air. Long pale stems and small tough leaves mean the plant is flowering or the pot is exhausted, and both are answered by cutting it back. The ledger below has the rest.