The Best Mint Varieties to Grow (and How to Keep Mint in Check)

Mint is the easiest herb you can grow in a cool, wet climate and the only one that needs a fence. One plant in moist soil will give you leaves from April to October for ten years or more, and the same plant left loose in a bed will take the bed. This guide covers the three mints we grow at the nursery and what each one is for, why real peppermint cannot be grown from seed, the containment methods that actually hold, and the cutting routine that keeps a plant young. It is written from Co. Wicklow, and mint behaves the same way in every garden from Cornwall to Denmark.

Short on time? A peppermint plant in a 10 litre pot by the back door is the whole answer for tea. Keep it watered and cut it hard twice a summer.

Why Mint Runs, and Why That Is Useful

Mint spreads by rhizomes: underground stems that creep sideways just below the surface, rooting at every joint and sending up a new shoot every few centimetres. In the damp meadows and stream banks where the genus (Mentha) evolved, that is how a plant survives being grazed, flooded and trampled. In a garden it means a single plant becomes a square metre in two seasons and a bed in five, and that every piece of rhizome left behind when you dig it out grows again.

The same habit is useful once it is contained. Mint makes a dense, weed-proof ground cover in a strip it cannot leave, it tolerates light shade and wet soil, and its flowers in August are covered in bees and hoverflies at a time when little else in the herb bed is flowering. In a food forest it can carpet a contained strip under fruit trees; our post on what to plant under a fruit tree covers that ground layer.

Peppermint Is a Hybrid, Which Is Why You Buy a Plant

Peppermint (Mentha x piperita) is a natural cross between water mint and spearmint, and like most hybrids it is sterile. It sets almost no viable seed, so every peppermint plant in the world is a division or a cutting of another peppermint plant. Seed sold as peppermint is spearmint or a mixed-up mint that smells vaguely minty and tastes of very little. The only way to get real peppermint, with the menthol hit that makes a proper tea, is to buy a plant or take a cutting from one.

That is also why mint varieties vary so much from one garden centre to the next. A plant labelled "mint" could be spearmint, apple mint, a feeble seedling or peppermint. At Earthling Plants we propagate ours by division from known stock, so a chocolate mint is a chocolate mint.

The Mints We Grow and What Each One Is For

Peppermint (Mentha x piperita) is the mint for tea. It has dark, slightly purple-tinged stems, a sharp menthol scent, and leaves that make a tea strong enough to taste of something without sugar. It is also the one to use in dark chocolate desserts. Peppermint is hardy to well below minus 15 °C and dies back to the ground each winter.

Chocolate mint is a cultivar of peppermint with darker leaves, bronze stems and a scent that most people place as After Eights within a second. The flavour is sweeter and rounder than straight peppermint, which makes it the one for children, for ice cream, and for a tea that needs no honey. Chocolate mint grows and runs exactly like peppermint.

Water mint (Mentha aquatica) is the native mint of Irish and British ditches, pond margins and wet meadows, and one parent of peppermint. It has rounder, hairier leaves, lilac flower heads that bees work hard in late summer, and a stronger, almost medicinal scent. It will grow in standing water, which makes water mint the plant for the boggy corner, the pond edge or a bucket with no drainage holes, and it makes a sharp, clean tea.

Spearmint (Mentha spicata) is the mint sauce and mojito mint, milder and sweeter, with bright green pointed leaves. We do not list it at the moment, but it grows the same way as the three above and is worth a separate pot if you cook lamb.

Mint Quick Facts

• Latin name: Mentha (peppermint Mentha x piperita, water mint Mentha aquatica)

• Type: hardy herbaceous perennial, dies back in winter

• Hardiness: to minus 15 °C and below; untroubled by any Irish or British winter

• Position: sun or part shade; peppermint tastes stronger in sun

• Soil: moist, any type; water mint takes waterlogged ground

• Spread: indefinite by rhizome; contain it

• Height: 40 to 80 cm

• Planting: any time from March to October

• Harvest: April to October, best just before flowering

• Lifespan: indefinite if divided every two or three years

Step 1: Decide How to Contain It

Do this before the plant arrives. The best method for most gardens is a pot of 10 litres or more, standing on a hard surface where runners that escape over the rim cannot root. The second best is a pot sunk into the bed with its rim 2 to 3 cm above the soil, which hides the pot and stops the runners crossing. A bottomless bucket or a 40 cm length of large drainpipe sunk into the ground does the same job and gives more root room.

The method that does not work is "I'll keep an eye on it". Mint in open ground with nothing round it needs lifting every spring, every rhizome removed, and one piece replanted, and most people stop doing that in year three. If you want mint as ground cover, give it a strip bounded by a path on one side and a wall or a buried barrier on the other.

Step 2: Plant It

Mint can be planted in any month from March to October. In a pot, use a loam-based compost, fill it to 3 cm below the rim, and plant one mint per pot; two varieties in one pot will tangle together within a season, and one always wins. In the ground, dig in a bucket of compost and set the plant at the depth it was growing. Water it in and keep it moist for the first month.

Mint is one of the few herbs that is happy in part shade and in heavy, damp soil, so it can take the spot the Mediterranean herbs would die in. Give peppermint some sun if you can; the leaves make more oil, and the tea is better for it.

Step 3: Keep It Productive

Mint gets better the more you cut it. Snip shoots from the top from April onwards, and when the plant reaches 30 cm or starts to look leggy, cut the whole thing back to 5 cm. It regrows within a fortnight, fresher and bushier. Do that at least twice a summer and again after it flowers in August, and you will have soft young leaves until the first frosts.

Water pots daily in a dry spell, because mint wilts fast and recovers slowly. Feed lightly, with a liquid seaweed feed once a month or a mulch of compost in spring; too much feed makes soft growth with little flavour. Every two or three years, in March, tip the pot out, cut the root mass into quarters, discard the woody centre and replant one outer quarter in fresh compost. This is the single most important job for mint in a pot, and the reason old mint goes bald in the middle.

Step 4: Harvest and Use

Pick in the morning, before flowering, when the oil content is highest; once a mint flowers the leaves turn coarser and the flavour drops. For tea, a sprig of six or eight peppermint leaves in a mug of water just off the boil, steeped for five minutes, is the whole recipe. Chocolate mint does the same without the sharpness.

Mint dries well: hang bunches in a warm, airy room for a week, then strip the leaves into a jar. It freezes well chopped into ice cube trays with a little water. Fresh, it goes into mint sauce for lamb, tabbouleh, new potatoes, peas, and anything with cucumber or yoghurt.

Troubleshooting Mint

Orange pustules under the leaves. Mint rust. Cut the plant to the ground, bin the cuttings (not the compost heap), and the regrowth is usually clean. Badly affected plants are replaced by division from a clean one.

Bald in the middle, growing at the edges. The plant has outgrown its pot. Divide it in spring and replant an outer piece.

Weak flavour. Too much shade, too much feed, or the plant has flowered. Move it into more sun, stop feeding, and cut it back hard.

Mint everywhere. It was never contained. Lift the whole patch, sieve the soil for rhizome pieces, and replant one piece in a sunk pot.

Wilting in a pot. Thirst. Mint in a pot needs water every day in summer.

FAQ: Growing Mint

Does mint come back every year? Yes. Mint is a hardy herbaceous perennial: the top growth dies back in November and the rhizomes send up new shoots in March or April. A plant divided every two or three years lives indefinitely. No winter protection is needed in Ireland or Britain.

How do I stop mint from spreading? Grow it in a pot, either free-standing on a hard surface or sunk into the bed with the rim 2 to 3 cm above the soil. A bottomless bucket sunk 40 cm into the ground also works. In open ground the only control is lifting and replanting a single piece every spring.

Can I grow mint from seed? Spearmint and a few others, yes, though seedlings vary. Peppermint, no: it is a sterile hybrid that sets no true seed, so anything sold as peppermint seed is something else. Buy a peppermint plant or take a cutting from one.

Which mint is best for tea? Peppermint, for its menthol strength, with chocolate mint a close second for a sweeter cup. Water mint makes a sharper, more aromatic tea. Spearmint is milder and better suited to Moroccan-style sweet tea.

Why is my mint dying in the middle? The plant is root-bound. Mint grows outwards and the centre of an old clump goes woody and bare. Tip the pot out in March, cut away the dead centre, and replant a vigorous outer section in fresh compost.

Which Mint to Start With

Earthling Plants grows peppermint, chocolate mint and water mint at our nursery in Co. Wicklow, propagated by division from known plants, and ships them across Ireland, the UK and the EU. For tea, start with the peppermint. For a wet corner, the water mint. For a plant that children will pick and eat on the way past, the chocolate mint. Each one in its own pot, and the garden stays yours. Mint belongs with the other plant-once crops in our perennial vegetables guide, and its August flowers earn it a place among the pollinator plants too.

Related reading: Perennial vegetables for Irish gardens · The best pollinator plants · Companion planting: what actually works