Mint care for pots, kitchen windows and balconies

Mint wants direct sun for part of the day, soil that never dries out, and regular picking. Given those it grows fast enough to take over a garden bed, which is why it belongs in a container. This page covers light, watering, harvesting, cats and dogs, and what changes in a small pot.

Give it at least three hours of direct sun, on a bright window or a sheltered balcony.
Keep the soil evenly moist and check it with a finger, because a small pot dries fast.
Pick the shoot tips often and pinch out flower buds to keep it bushy.

Which mint you have: spearmint, peppermint or a flavoured one

Most mint sold in a pot is spearmint or peppermint, and the label does not always say which. Crush a leaf and smell it before you decide what to use it for. The University of Florida counts 19 or so species and many crosses in the genus, and the care on this page holds for every one sold as a kitchen herb.

Spearmint. Mentha spicata, the garden mint. Bright green, nearly hairless leaves with toothed edges, and the one most recipes mean by mint.
Peppermint. Mentha × piperita, a hybrid of watermint and spearmint. NC State lists it for teas, syrups, sweets and ice cream.
Flavoured mints. Apple, orange and chocolate mint take the same care. Variegated kinds such as pineapple mint are the exception on sun.

Does mint spread? Why it belongs in a container

Yes. NC State Extension says spearmint spreads aggressively, by underground rhizomes and by stems that root wherever they touch the ground. Utah State University Extension says it out-competes most garden plants in open ground, and recommends containers or a bed where the roots are confined.

A container works because the rhizomes have nowhere to run, and the stems are what escape. For a pot sunk into a bed, the RHS says to leave the rim above the surface so shoots cannot root over the top. On a balcony the same goes for a stem that drapes onto the pot next to it. Pull out any runner that heads over the edge the day you see it.

How much sun mint needs, indoors and outside

Direct sun for part of the day, and more is better. NC State Extension gives peppermint a minimum of three hours of sun a day and lists both mints for full sun or part shade. A south or west window, a kitchen sill that gets the afternoon, or a sheltered balcony all qualify.

Too little light shows in the stem. It stretches, the gaps between leaf pairs grow, and the new leaves come in smaller and paler. A room lit by one north window, or a wall well back from the glass, is not enough, and feeding does not fix it. If that is the only wall you have, low light houseplants covers what grows there instead.

In summer the other end matters. Utah State University Extension notes that full sun can scorch variegated kinds such as pineapple mint, and the RHS suggests moving pots somewhere shadier in hot weather so they need less water. On a south-facing balcony in July, morning sun and afternoon shade is the easier spot.

Watering mint in a pot so it never dries out

Water when the top of the soil starts to feel dry, and never let the pot dry right through. NC State says spearmint does not do well in dry soils, and the RHS warns that containers dry out faster than open ground, so a potted mint needs checking regularly while it is growing.

Light and pot size decide how often that is. The same plant drinks far faster in a sunny window than in part shade, and a small pot full of roots dries faster than a large one. Push a finger in to the first knuckle each time you pass, and water slowly until the whole pot is evenly damp.

Keep it moist without leaving it standing in water. Utah State University Extension says overwatering leads to disease and that rust follows leaves left wet overnight, so water the soil rather than the foliage, and do it in the morning. If you go away, DIY drip irrigation covers ways to keep a pot watered while you are gone.

Soil, feeding and repotting a mint plant

A peat-free compost, one light feed in spring, and a fresh start whenever the roots fill the pot. The RHS says most mints tolerate a range of soils, and Utah State University Extension describes the ideal as rich, moist and slightly acidic.

Compost. The RHS recommends multipurpose or soil-based peat-free compost for mint in a container. Fill to a couple of centimetres below the rim so water does not run straight off.
Feeding. One dose of a balanced fertiliser as growth starts in spring. Utah State University Extension warns that overfeeding promotes rust and lowers the oil that flavours the leaf.
Repotting. The RHS says container mint needs repotting regularly, how often depending on the size of the container. When roots circle the pot and it dries faster than it used to, split it and replant one piece in fresh compost.

How to harvest mint so the plant stays bushy

Pick little and often, from the top. Utah State University Extension says you can start once the plant is 7 to 10 cm tall, and the RHS says the young, soft shoot tips carry the strongest flavour. Cut each stem just above a pair of leaves. NC State notes that regular pinching of the tips gives a bushier, leafier plant.

Flower buds are the signal to cut harder. Once mint blooms, Utah State University Extension says the oil content of the leaves drops and they taste weaker, so pinch the buds out as they appear. If it flowers anyway, the RHS advice is to cut the whole plant down to about 5 cm from the base to bring on fresh leaves.

Use the leaves fresh, or dry them. The University of Florida says mint leaves hold so much moisture that they need a dark, dry place to dry in, or they turn dark and mouldy.

Is mint toxic to cats and dogs?

Yes, on the ASPCA listing. The ASPCA lists mint, Mentha, as toxic to dogs, cats and horses, names the essential oils as the toxic principle, and gives vomiting and diarrhoea after large amounts eaten as the signs.

Hang or stand it where the animal cannot reach it. If a pet has eaten a good amount, call a vet or the ASPCA Animal Poison Control line rather than waiting to see what happens. For a green plant within reach of the cat, the ASPCA lists the spider plant as non-toxic to cats and dogs.

Mint on the wall

A pocket on a wall solves the containment problem the extension services raise, because the rhizomes have no soil beyond the pocket to root into. Hung beside a kitchen window or on a sheltered balcony, it also puts the shoot tips at picking height. Give it the lowest pocket on the board so its stems drape onto nothing, and design your canvas lets you try the layout before you hang anything.

Size is the limit. NC State suggests a pot 30 to 40 cm across for peppermint, and the Medium pocket holds 1.8 litres of substrate, about what a 15 cm pot takes. In that volume the roots fill the pocket sooner and dry it faster, so pick harder, check the soil more often, and divide the plant once the roots pack the pocket. The Small and Mini pockets hold too little soil for a plant this thirsty.

The board hangs by a slot near its top on one wall hook, so the wall side is one hook in one hole, made with a drill or, on a wall that takes one, a nail. The canvas works indoors and outside on a sheltered balcony or terrace, where only the wooden board needs keeping out of the rain. The mounting guide goes through it step by step.

Take a young mint plant out of its pot.
Loosen the root ball with your fingers until it fits the pocket.
Sit it in, fill around it with substrate and press lightly.
Water slowly, in measured amounts, until the substrate is evenly damp.

Mint problems: leggy stems, rust and wilting

Most mint problems come down to light or water, and the stems tell you which. Long bare stems with small pale leaves mean too little sun. A plant that wilts and recovers after watering is running short, and one that yellows from the bottom while the soil is still wet has had too much. The other causes of yellowing, on any plant, are in what yellow leaves are telling you.

Soil kept moist all the time, which this plant needs, also suits fungus gnats, the small black flies that rise from the pot when you water it. Fungus gnats in houseplants covers what reaches the larvae in the soil.

What you see	Why	The fix
Long bare stems, small pale leaves	Too little direct sun	Move it to a sunnier window and cut the stems back to a pair of leaves.
Wilts, then recovers after watering	The pot is drying out, often because roots have filled it	Check it more often, and divide the plant if roots circle the pot.
Yellow lower leaves in wet soil	Overwatering	Let the top of the soil dry before watering again.
Dusty orange, yellow or black spots on the leaves	Mint rust, a fungal disease the RHS calls common on garden mint	Cut out spotted stems, water the soil in the morning and stop feeding.
Weak flavour and flower spikes at the tips	Flowering, which lowers the oil in the leaf	Pinch the buds out, or cut the plant to 5 cm after flowering.
Clusters of small insects on the shoot tips	Aphids	Rinse them off with water or spray insecticidal soap.

How to propagate mint from cuttings or by division

Two methods work. A cutting starts a plant from a bunch of shop-bought stems or a friend’s pot, and division renews a pot the roots have filled. The RHS says mint stems root readily in a jar of water.

Cut a soft shoot tip just below a pair of leaves, in spring or summer.
Strip the leaves from the lower half so none sit in the water.
Stand it in a jar of water on a bright windowsill and top the water up as it drops.
Pot it in peat-free compost once the new roots are a few centimetres long.
To divide, tip the plant out in spring or autumn and cut the root mass into pieces.
Discard the old, dead centre and replant the younger outer pieces in fresh compost.

In a small pot or a pocket, division is the routine every time the roots fill it, because it gives the roots their space back and leaves spare pieces for another pot. The plant care guide lists the other plants for a pocket, with the light and water each one takes.

Can you grow mint indoors all year?

Yes, on a window that gets direct sun. The RHS suggests bringing potted mint indoors in autumn and standing it on a sunny windowsill to keep picking through winter. Growth slows in the short days, so pick less and expect the soil to take longer to dry.

Does mint come back every year?

Yes. It is a perennial, and outdoors the stems die back over winter and new shoots come from the roots in spring. The RHS says the old stems can be cut back any time from late autumn until just before the new shoots appear.

Can you grow mint from seed?

You can, but you rarely get the plant you wanted. Utah State University Extension says mints cross so readily that seedlings often do not come true, and peppermint is itself a hybrid. Buy a plant, or root a cutting from one whose taste you like.

Can mint share a pot with other herbs?

Not for long. Utah State University Extension says mint out-competes most garden plants, and in a shared pot its roots take the space from whatever is planted beside it. Give mint a pot or a pocket of its own and keep the other herbs next to it.

Which mint is better for cooking, spearmint or peppermint?

Spearmint, for most kitchens. The RHS says it has many culinary uses and is the one to grow if you only have room for one mint. NC State lists peppermint for teas, sweets and ice cream, so it makes a good second pot if you drink mint tea.