How to Grow Food on a Windowsill

A windowsill is the smallest growing space there is, and one of the most useful. With nothing more than a bright sill, a few pots and some peat-free compost, you can keep yourself in fresh herbs, salad leaves and microgreens all year — no garden, no balcony, not even a back door required. It is also the gentlest possible introduction to growing food, because everything is within arm's reach and there are no slugs to fight.

This guide covers what actually thrives indoors, how to give it enough light, the right pots and compost, and how to water without killing things — the most common indoor mistake by far. If you fancy stepping up to bigger pots later, it all builds neatly towards proper container growing on a patio or balcony.

What you can grow indoors

Not everything will crop on a sill, but more does than you might think. The trick is to choose crops that are small, fast, or grown for their leaves rather than fruit.

• Herbs — basil, parsley, chives, mint and coriander are the windowsill classics. They are picked young and often, so they never need much room.
• Cut-and-come-again salad leaves — loose-leaf lettuce, mixed salad blends and oriental leaves like mizuna and pak choi. You snip the outer leaves and the plant keeps going.
• Rocket — fast, peppery and happy in a shallow trough. One of the most rewarding indoor leaves.
• Microgreens — the seedlings of crops like radish, broccoli, beetroot and cress, harvested at 2–4cm. Ready in a week or two and astonishingly easy.
• Pea shoots — sweet, crunchy tendrils grown from ordinary dried marrowfat peas. The fastest filling crop of all.
• Chillies — a sunny sill genuinely suits chillies, which like warmth and shelter. They need your brightest spot and patience, but a single plant can crop for months.

Avoid trying to grow anything large or fruiting (tomatoes, courgettes, root veg) on an indoor sill — they need far more light and root room than a window gives. Save those for outdoors.

Light — the make-or-break factor

Light is the single thing that decides whether windowsill growing works. Indoors, light levels drop off sharply just a metre from the glass, so the sill itself is the only spot bright enough for most edibles.

A south- or west-facing windowsill is ideal: it catches four or more hours of direct sun, which suits herbs, chillies and salad alike. An east-facing sill gets gentler morning light and works fine for leafy crops, herbs and microgreens. A north-facing sill is too dim for most food plants — you can still grow microgreens and pea shoots there, but anything longer-term will struggle without help.

The classic sign of too little light is leggy, pale growth: thin, stretched stems reaching towards the glass, with widely spaced leaves and a washed-out colour. If you see that, move the plant to a brighter window or thin it out.

If your brightest window still isn't enough — common in a north-facing flat, or through the dark months — a small LED grow light is a tidy fix. Modern clip-on or strip lights are cheap to run, sit discreetly over a sill, and let you grow leafy crops and herbs through the worst of winter. You don't need one to start, but it is the obvious upgrade if your plants keep going leggy.

Pots and compost

The two things every windowsill pot needs are drainage holes and a saucer. Without holes, water pools at the bottom and rots the roots; without a saucer, you flood the sill. Any pot will do — repurposed yoghurt pots, a long trough, terracotta, or proper plant pots — as long as water can escape.

A trough or window box sized to your sill is the most efficient choice for salad and herbs: it gives a continuous strip of growing room and one tidy saucer or drip tray to catch the run-off. For single herbs or a chilli, a pot 12–15cm across is plenty.

Fill them with peat-free multipurpose compost. Peat-free is the standard now in the UK on environmental grounds, and it is perfectly good for indoor growing — just keep an eye on watering, as some peat-free mixes dry at the surface while staying damp below. For microgreens and pea shoots you barely need compost at all: a shallow 2–3cm layer is enough, since you harvest before the roots get going.

Watering indoors

Over-watering is the commonest killer of windowsill plants by a wide margin. Indoors there is no wind and little warmth to dry the compost, so it stays wet far longer than it would outside — and soggy compost suffocates the roots.

The fix is simple: use the finger test. Push a fingertip about 2cm into the compost. If it feels damp, leave it. If the surface is dry and the pot feels light, water it — slowly, until a little drains into the saucer, then tip away any standing water after ten minutes. Never let a pot sit in a full saucer.

One exception to the keep-it-on-the-dry-side rule is basil, which loves warmth and humidity and sulks in dry indoor air. Stand its pot on a saucer of damp gravel, mist it occasionally, and keep it out of cold draughts — it will reward you for it.

Crop-by-crop quick tips

Basil. The trickiest of the popular herbs indoors: it wants your warmest, brightest sill, even moisture and no chill. Pinch out the growing tips regularly to keep it bushy. Our full guide to growing basil walks through it from seed to harvest.

Salad and rocket. Sow a pinch of seed thinly across a trough, keep it lightly moist, and start picking outer leaves once they reach 8–10cm. Sow a fresh batch every few weeks so you never run out — the same cut-and-come-again approach used for growing lettuce outdoors works perfectly on a sill. Rocket is even quicker and tolerates a slightly dimmer window.

Microgreens and pea shoots. The fastest, most beginner-proof crops of the lot. Scatter seed densely over a shallow tray of compost, keep it damp, and snip the seedlings with scissors after one to three weeks. Pea shoots from a bag of ordinary dried peas (soaked overnight first) will often re-sprout for a second cut. These are the ideal first thing to grow with children.

Keeping supermarket herbs alive. Those pots of basil, parsley or coriander from the supermarket are crammed with dozens of seedlings fighting for root room, which is why they collapse within a week. Rescue them by tipping the pot out, gently splitting the root ball into three or four clumps, and re-potting each clump into its own pot of fresh peat-free compost. Given space, light and sensible watering, they carry on for months rather than days.

A year-round windowsill

The real joy of windowsill growing is that it never stops. When the garden is bare and frozen from November to February, a bright indoor sill keeps producing.

Through autumn and winter, sow hardy winter salad leaves — mizuna, winter lettuce, lamb's lettuce and rocket — which grow slowly but steadily on a cool, bright sill and give you fresh leaves when shop salad is dear and tired. Hardy herbs like parsley and chives carry on too, and a pot of mint sees out the winter happily indoors. Microgreens and pea shoots don't care about the season at all: with a grow light, you can crop them every couple of weeks right through the darkest months.

To time fresh sowings and keep something coming all year, our planting calendar gives the right UK sowing windows for each crop. And once a sunny sill has given you the confidence, the natural next step is a few bigger pots by the back door — start with our guide to growing food in containers, or browse the rest of the container growing section for ideas that suit a balcony or patio.