Growing and containing mint: plenty of aroma, clear boundaries

Mint is the herb where beginners and old hands make the same mistake: they simply plant it in the bed. A year later the mint is among the strawberries, in the lawn and next door. Yet it is one of the most rewarding kitchen herbs there is, you just have to set it clear limits from the start. Do that, and you have fresh mint all summer for tea, salads and cool drinks.

Why mint has to be contained

The reason for its urge to spread lies underground. Mint forms rhizomes, horizontal underground runners that creep in all directions and send up new shoots everywhere. In loose, moist soil it gains half a metre and more per year and crowds out its neighbours. Above ground it self-seeds as well, if you let it flower.

1. A pot as the simplest barrier

   Easiest of all, plant mint in a container from about 30 cm across. Stand it on a hard surface or a saucer so the roots do not escape through the drainage hole.

2. Root barrier in the bed

   If you want it in the bed, sink an old bucket or a bottomless mortar tub at least 30 cm deep and leave the rim two to three centimetres proud. Plant the mint inside it.

3. Check the rim

   Look once or twice a year whether runners have climbed over the rim, and cut them off. That is all the care the boundary needs.

4. Keep the flowers in check

   Cut off most flower heads before they set seed, then the mint cannot self-sow either.

Spot and soil: part shade and moist

Unlike thyme and sage, mint comes from damp banks and meadows. It loves a part-shaded spot with humus-rich, evenly moist soil. It only takes full, blazing sun if the soil never dries out completely. In light shade under shrubs or on the north side it is often happiest.

The soil may well be rich. A handful of compost in spring and regular watering in dry weeks keep the leaves large and aromatic. In a pot it dries out faster, so reach for the watering can more often there.

Harvesting and cutting

You harvest mint, like most leaf herbs, best as a whole shoot tip, not as a single leaf. Cut above a pair of leaves, then the shoot branches and the plant grows bushier. Most aromatic are the leaves just before flowering, when the content of essential oils peaks.

If the mint turns unsightly in high summer after flowering, cut the whole stand back a hand's width above the ground. It then re-sprouts fresh and tender and gives you a second harvest for late summer.

Flowers and insects

If you let part of the mint flower, in high summer it becomes one of the best insect magnets in the garden. Bees, bumblebees, hoverflies and many butterflies love the pale violet flower spikes. For leaf quality the flowering is a downside, but a flowering strip at the edge of your root barrier costs you little and helps the insects a lot.

Varieties: from peppermint to chocolate mint

A note on keeping varieties true: if several mints stand close together, their aromas mingle over time and seedlings cross. If you want to keep the pure taste of a particular variety, hold it in separate pots.

Propagating: child's play

If mint has one talent, it is propagating. A piece of runner with a few roots, separated in spring and replanted, almost always takes. Cuttings are even easier: a shoot without flowers roots even in a glass of water on the windowsill within one to two weeks. From one bought plant you effortlessly raise more supply and gifts.

In the kitchen and as tea

Fresh mint is unbeatable in summer: in the water jug with lemon, in tabbouleh, over peas or strawberries, in homemade mint tea. For tea, pour hot water over a handful of fresh shoot tips and let them steep for a few minutes. To dry, tie the shoots and hang them upside down in the shade; dried mint keeps its aroma well for the winter pot.

Enter setting the root barrier and the summer cut back in your garden journal. Then the mint stays what it should be: a generous gift that does not overrun you.

Common questions about mint

How do I stop mint spreading through the bed?

Plant it in a pot or a root barrier: a bottomless bucket or tub sunk at least 30 cm deep with the rim a few centimetres proud. Check the rim once or twice a year for escaped runners and cut the flowers before they set seed.

What spot does mint like?

Part shade to sun with humus-rich, evenly moist soil. Unlike Mediterranean herbs it does not want it dry and lean. In full sun only with enough water.

Why does my mint taste bland?

Often because it is in full flower or suffering from drought. Harvest the shoot tips before flowering, keep the soil moist and cut aged stands back completely once. Several varieties close together can also dilute the aroma.

Is mint hardy?

Yes, the common garden mints are fully hardy. They die back completely in winter and re-sprout reliably in spring. Stand pots sheltered by the house wall so the root ball does not freeze right through.

Can I propagate mint easily?

Very easily. In spring separate a piece of runner with roots and replant it, or stand a flowerless shoot in a glass of water. After one to two weeks it forms roots and can be planted out.