Why a Windowsill Is the Best Small Space You Own

If you have a kitchen window that catches a few hours of sun, you already have room for a herb garden. A sill roughly a metre wide will comfortably hold six or seven small pots, which is enough to keep a household in fresh basil, mint and chives for most of the year. Herbs are forgiving plants, and the ones we use most in British cooking happen to be among the easiest to grow indoors. You do not need a greenhouse, a garden or any particular skill — just bright light, the right pot sizes and a little routine.

There is a real pleasure in pinching a few leaves straight into a pan of tomatoes or a bowl of new potatoes. Cut herbs also cost a small fortune in the supermarkets, and the pots you buy there are often crammed with seedlings that sulk and die within a fortnight. Growing your own sidesteps all of that.

Choosing Herbs That Genuinely Thrive Indoors

Not every herb is happy on a sill. Rosemary and thyme want drier, grittier conditions and often struggle in centrally heated rooms, while coriander bolts quickly in warmth. The reliable trio is basil, mint and chives.

• Basil — needs the brightest spot you have, ideally six hours of direct sun. It hates cold, so keep it above 15°C and away from draughty windows in winter.
• Mint — tough, fast-growing and happy in partial shade. Grow it in its own pot, always, because it spreads aggressively and will swamp anything nearby.
• Chives — the most tolerant of the three. They cope with a north-facing sill, regrow after cutting and will quietly keep going for years if divided occasionally.

If you have a very sunny, south-facing window, add flat-leaf parsley or a compact bush basil. If your sill is shaded, stick with mint and chives and accept that basil will stretch and pale.

Pots, Compost and Drainage

Size matters more than most people expect. Use pots at least 13–15cm across for a single basil plant, and 20cm for mint. Chives are happiest in a pot around 15cm deep, as they build a dense mat of roots. Terracotta looks lovely but dries out fast; glazed ceramic or sturdy plastic holds moisture better on a warm sill.

Every pot needs drainage holes, and every pot needs a saucer underneath. Without holes, compost turns sour and roots rot. Without saucers, you will be wiping the sill every time you water. Stand pots on a layer of small pebbles if you have a habit of overwatering — it lifts the base clear of any water that collects.

Use a peat-free multipurpose compost and mix in about a quarter by volume of perlite or horticultural grit. That extra drainage makes a real difference indoors, where air movement is limited and compost dries unevenly. Fill pots to about 2cm below the rim so you can water properly without it running straight over the edge.

Sowing, Planting and the First Few Weeks

You can raise herbs from seed, but for basil and mint it is far quicker to buy a living pot from a supermarket or garden centre and split it. Tip the plant out, tease the roots apart gently and pot each clump separately. Water well and keep out of direct sun for two or three days while they settle.

For chives, seed is straightforward. Scatter thinly on the surface of damp compost, cover with a bare 5mm of compost and keep at around 18°C. Germination takes roughly two weeks. Thin seedlings to about 3cm apart once they are large enough to handle.

Basil seed sown indoors in spring germinates in five to ten days at 20°C. Sow it in late March for a summer supply, and again in August for a windowsill crop through autumn and winter.

Watering, Feeding and Harvesting Well

Indoor herbs die from overwatering far more often than from drought. Check the compost with your finger before reaching for the can — if it is damp 2cm down, wait. In summer you may water every other day; in winter, once a week is often plenty.

Water at the base of the plant rather than over the leaves, and let the pot drain fully. If you can, water in the morning so any splashes dry before evening.

• Feed with a diluted liquid seaweed or tomato feed every fortnight from March to September. Stop in winter, when growth slows.
• Pinch out basil tips above a pair of leaves to encourage bushy growth, and remove any flower buds as soon as they appear — flowering signals the leaves to turn bitter.
• Cut chives with scissors about 2cm above the compost, and they will regrow within a few weeks.
• Harvest mint regularly, taking the top two or three pairs of leaves. Regular picking keeps plants compact and productive.
• Rotate pots a quarter turn each week so stems grow straight rather than leaning towards the glass.

Keeping Plants Healthy on a Sill

Leggy, pale basil usually means too little light. Move it closer to the glass, and if that is not enough, a small clip-on grow light for a few hours each evening will transform results in winter.

Watch for greenfly and whitefly on soft new growth, and for fine webbing that suggests red spider mite — a common problem in warm, dry rooms. A firm spray with water, or a dilute soap solution, usually brings small infestations under control. Fungus gnats, the little flies that hover over compost, point to consistently wet soil: let the surface dry out between waterings and they will fade away.

With bright light, sensible watering and a fortnightly feed, a modest windowsill will give you fresh herbs right through the year — and there is no seasoning quite as satisfying as one you grew yourself.