Why Containers Suit the British Patio

Not every smallholder has a walled kitchen garden or a deep, friable bed of loam waiting to be planted. Many of us have a flagged patio, a gravel yard behind the shed, or a few square feet of paving outside the back door. That is no reason to go without fresh herbs. In fact, containers often outperform open ground for the Mediterranean stalwarts — rosemary, thyme and mint — because you control the drainage, the soil mix and the shelter. On a wet British summer, a pot that drains freely is worth more than a border that sits waterlogged for a fortnight.

The trick is to treat each pot as its own small growing environment. Get the depth, the compost and the watering right, and you will be cropping herbs from March through to the first hard frost, with a good deal more in between.

Choosing the Right Pots and Compost

Depth matters more than width for herbs. Rosemary and thyme send down a taproot and resent being cramped, so aim for pots at least 30cm deep, and 35–40cm for a mature rosemary. Mint is shallower-rooted but spreads aggressively, so a wide pot of 25–30cm works well.

Drainage is non-negotiable. Every container needs crocks or a good layer of broken polystyrene in the base, and plenty of holes. Terracotta is traditional and breathes nicely, though it dries out faster in a hot spell. Glazed ceramic or frost-proof plastic holds moisture better and survives a hard winter without cracking. Whichever you choose, raise the pot on feet or bricks so water never sits underneath.

For compost, a soil-based mix such as John Innes No. 2 gives herbs the weight and structure they like, with a handful of horticultural grit or sharp sand worked through for extra drainage. Peat-free multipurpose works too, but add grit and a little garden soil to stop it drying to dust in July. Rosemary, thyme and sage also appreciate a sprinkle of lime — a tablespoon of garden lime per pot keeps them sweet.

Planting Rosemary, Mint and Thyme

Rosemary is the shrub of the trio and needs the most room. Buy a young plant rather than growing from seed, which is slow and erratic. Plant it so the rootball sits level with the compost surface, firm gently, and water in. Give it the sunniest spot on the patio, against a south-facing wall if you can. It will shrug off frost if the pot is free-draining, though in a cold snap it is worth wrapping the pot in bubble wrap or hessian to protect the roots.

Thyme likes similar conditions but is smaller and more forgiving. Common thyme, lemon thyme and creeping thyme all do well in a shallow, gritty mix. Plant several varieties together in one wide bowl for a lovely display and a mixed harvest. Thyme resents wet feet above all else, so err on the side of a leaner compost and water sparingly.

Mint is the opposite character entirely. It loves moisture and will romp away, so keep it in its own pot — never share with anything else, or it will smother its neighbours. A rich, moisture-retentive compost suits it fine. Plant mint slightly deeper than it was in its nursery pot, water generously, and stand the pot in a saucer during dry spells. Even so, lift and divide it every couple of years, or the roots will mat into a solid plug.

If you are planting in spring, wait until the last hard frost has passed in your area — mid-May for most of the UK, later in the north. Keep new plants sheltered for a week or two before moving them into full sun.

Watering, Feeding and Patio Position

Container herbs dry out faster than border plants, especially in terracotta and on a windy patio. Check daily in summer by pushing a finger into the top inch of compost. Rosemary and thyme want the compost to dry out between waterings; mint prefers to stay consistently moist. Early morning is the best time to water, so foliage dries before evening and avoids mildew.

Feeding should be light. Overfed herbs grow soft, sappy and tasteless — exactly what you do not want. A weak liquid feed of seaweed or comfrey every three or four weeks from May to August is plenty for mint, and half that for rosemary and thyme. A top dressing of compost in spring is often all the Mediterranean herbs need.

Position is everything. Give rosemary and thyme full sun — six hours or more. Mint tolerates a little shade, especially in the afternoon, and actually prefers it in hot spells. Turn pots a quarter turn each week so they grow evenly rather than leaning towards the light.

Picking for Tenderness and Flavour

Regular picking is the secret to tender, flavoursome leaves. Left alone, rosemary turns woody and thyme goes leggy and tough. Snip little and often — a few sprigs each week — and the plant responds by pushing out fresh, soft growth.

• Pinch the tips of rosemary and thyme rather than cutting back into old wood, which rarely regrows.
• Harvest mint from the top, taking whole stems just above a leaf pair to encourage bushy growth.
• Never strip more than a third of a plant at once, and give it a fortnight to recover.
• Pick in the morning after dew has dried, when essential oils are at their peak.
• Stop heavy harvesting of rosemary and thyme by early September so new growth hardens before winter.

Use the cuttings straight away — a scatter of thyme over roast chicken, rosemary pushed into lamb, mint torn into new potatoes or a jug of Pimm's. Anything spare can be tied in bunches and hung in a cool, airy shed to dry, or frozen in ice cube trays with a little water.

Overwintering and Common Troubles

British winters are the main threat to container herbs, not because of the cold itself but because of wet roots and repeated freeze-thaw. Move pots against a sheltered wall, stand them on feet to keep drainage clear, and cut back on watering drastically. Do not feed at all between November and March. A layer of grit or bark on the surface helps stop the compost becoming sodden.

Watch for aphids on soft mint growth — a sharp spray of water usually deals with them. Rosemary beetle, with its metallic green and purple stripes, can strip foliage; pick the beetles off by hand in the evening. Root rot, grey mould and vine weevil are all made worse by poor drainage, which is why the gritty compost and the raised pots matter so much.

Look after them and a modest patio will keep you in fresh herbs right through the year — a small, generous harvest that earns its place beside every kitchen door.