How to Grow Mint (Without Letting It Take Over)

Mint is the herb that grows almost in spite of you. It shrugs off shade, bounces back from brutal haircuts, and survives winters that kill fussier herbs outright. The only real skill in growing mint is containing it — because the same vigour that makes it beginner-proof also makes it one of the most invasive plants you can put in a border. Here is how to get endless fragrant leaves for tea, mojitos and cooking, without declaring war on your own garden.

Why mint must live in a container

Mint spreads by underground runners (stolons) that travel horizontally just below the surface, rooting and throwing up new shoots as they go. In open soil a single plant can carpet a square metre in one growing season and shrug off your attempts to dig it out — every fragment of runner left behind regrows. The fix is simple: keep it in a pot. If you want mint "in" a bed, sink a large container or bottomless bucket into the soil and leave 5 cm of rim proud of the surface so runners cannot arch over the top. Check once a year that nothing has escaped through the drainage holes.

Warning: never plant mint directly into a border or vegetable bed, however small the plant looks now. Gardeners spend years removing an established patch, and rotavating makes it worse — every chopped runner becomes a new plant.

Choosing a variety

There are hundreds of mints, and they are not interchangeable in the kitchen. The most useful are:

• Spearmint (Mentha spicata) — the classic all-rounder for cooking, salads and mojitos.
• Peppermint (Mentha × piperita) — higher menthol; the one for tea and desserts.
• Moroccan mint — a clean-tasting spearmint type, the traditional choice for sweet mint tea.
• Apple mint — soft, fuzzy leaves with a fruity edge; great in cold drinks.
• Chocolate mint — a peppermint type with an after-dinner-mint aroma.

Buy young plants or take cuttings rather than sowing seed. Peppermint is a sterile hybrid, so genuine peppermint cannot be grown from seed at all, and seed-raised spearmint is wildly variable in flavour. A single bought plant will give you all the cuttings you will ever need.

Planting

Plant mint in spring once hard frosts have passed, or in early autumn in mild areas. Choose a pot at least 25–30 cm wide, fill it with rich, moisture-retentive compost, and set one plant per pot — it will fill it within weeks. Mint is happy in full sun or part shade; in hot climates a spot with morning sun and afternoon shade keeps the leaves lush rather than scorched.

Watering and feeding

Forget everything you know about Mediterranean herbs. Rosemary and thyme like life hard and dry; mint likes it damp. Water whenever the top couple of centimetres of compost feel dry — in a summer heatwave that can mean daily for pots — and never let the root ball bake bone dry, which turns the leaves small, tough and dull-flavoured. A balanced liquid feed once a month through the growing season keeps potted mint productive; more than that produces lots of soft growth with less scent.

Harvesting for maximum flavour

The more you pick, the better mint gets. Pinch out shoot tips regularly from spring onwards — this keeps plants bushy instead of tall and floppy. Two or three times a season, be ruthless: shear the entire plant back to about 5 cm. Within a fortnight it responds with a flush of tender new leaves, which carry far more aromatic oil than old ones. Flavour peaks just before flowering, and leaves picked in the morning, after the dew dries but before the heat, are the most fragrant of all.

Tip: got more mint than you can use? Chop the leaves, pack them into ice-cube trays, top up with water and freeze — instant flavour cubes for drinks and sauces all winter. You can also root a supermarket bunch: stems stood in a glass of water grow roots within a week or two, ready to pot up.

Growing mint indoors

Mint grows well on a bright windowsill year-round, which is the easiest way to keep fresh leaves coming through winter. Give it the brightest window you have (or a small grow light in the darkest months), keep the compost lightly moist, and turn the pot every few days so it does not lean into the glass. Indoor mint grows softer and lankier than outdoor plants — just keep pinching.

Winter and keeping plants vigorous

Outdoors, mint dies back to the ground in autumn and looks convincingly dead all winter. It is not: the roots are very hardy, and fresh shoots reappear in spring. Cut the dead stems down, and in colder regions shove pots against a house wall. After two or three years, container mint gets congested, woody in the centre and less flavoursome. The fix is division: knock the plant out of its pot in early spring, slice the root ball into quarters, and repot the youngest, outer sections in fresh compost. You will lose nothing — each piece becomes a full plant by summer.

Common problems

• Mint rust — dusty orange pustules on the undersides of leaves. Cut affected stems to the ground and bin them (never compost); badly infected plants are best replaced with a clean cutting in fresh compost.
• Powdery mildew — a white film on leaves in crowded, dry-rooted plants. Water more consistently and thin stems for airflow.
• Aphids and spider mites — mostly on indoor or greenhouse mint. A hard rinse under the tap sorts most infestations; repeat weekly.
• Bare, woody centre — the pot is congested. Divide and repot as above.

Not sure whether you are looking at rust, mildew or something else? Photograph the worst leaf in PlantMe and the app's disease diagnosis will name the problem and give you a treatment plan in seconds.