A windowsill is the smallest, most generous patch in the house

If you live in a mews cottage or a compact townhouse, you'll know the feeling: you long to grow something, but outdoor space is a courtyard, a shared passage, or a couple of pots by the door. The good news is that the cottage-garden principle of small and often translates perfectly to a sunny windowsill. A deep sash sill catching light from a south or west-facing window is enough to keep you in cut-and-come-again salad leaves every week of the year. No greenhouse, no raised beds, no allotment queue. Just a few shallow trays, a bag of compost, and five minutes of attention every few days.

Choose leaves that earn their sill space

Not every salad crop suits a shallow tray. You want leaves that germinate quickly, tolerate close spacing, and regrow after cutting. Loose-leaf lettuces are the backbone: 'Salad Bowl', 'Lollo Rossa' and 'Green Oakleaf' all work well. Add peppery rocket, mizuna, mustard greens and pak choi for bite. Spinach and chard are good in cooler months, though they need slightly deeper compost.

• Cut-and-come-again lettuce: the most reliable windowsill crop.
• Rocket and mizuna: fast, sharp, and happy in a 5cm tray.
• Pea shoots and cress: ready in a fortnight, brilliant for winter.
• Claytonia and corn salad: hardy, mild, and productive in low light.

Avoid hearting lettuces, which need more room and time than a sill can give. In autumn, choose winter-hardy varieties rather than summer types that will sulk.

Shallow trays, honest compost, good drainage

Depth matters more than width. A tray 5–7cm deep is ideal: deep enough for roots, shallow enough to dry out and re-sow quickly. Reuse mushroom trays, seed trays, or clean food containers — just punch drainage holes in the base. Fill with sieved multipurpose compost mixed with a little vermiculite or horticultural grit, or use a seed-and-cutting compost. Don't press it down hard; aim for a light, crumbly tilth.

Sow thinly across the surface, then cover with a fine dusting of compost — about the depth of the seed itself. Water gently with a small can or mister, and stand the tray in a saucer. Sit the saucer on a folded tea towel if the sill is cold; it stops the chill travelling up through the roots.

Sow little and often — the fortnightly pinch

The biggest mistake on a windowsill is sowing a whole tray at once. You'll get a glut, then nothing. Instead, sow a small pinch every fortnight, or every ten days in summer. A single 30cm by 20cm tray will give two or three generous cuttings, so three trays on rotation is plenty for two people.

• Sow one tray, then another a fortnight later, then a third.
• Label each tray in pencil with variety and date.
• Thin seedlings to 2–3cm apart once they have two true leaves; eat the thinnings.
• In winter, stretch the interval to three weeks, as growth slows.

This rhythm suits mews living beautifully. There's no rush, no big dig, just a quiet fortnightly ritual with a cup of tea.

Water, light, and the British winter

Compost should stay moist like a wrung-out flannel, never sodden. Water from below by filling the saucer, and empty any that hasn't been taken up within an hour. In summer, check daily; in winter, every few days is enough. Mould and damping off come from cold, wet compost and still air, so open a window briefly when you can.

Light is the limiting factor from November to February. A south-facing sill is gold; east or west will do, but north will struggle. Turn trays a quarter-turn each day so stems grow straight rather than leaning into the glass. If light is short, grow pea shoots, cress and claytonia, which manage better than lettuce. Avoid placing trays directly above a radiator — dry heat is worse than shade. A sheet of white card behind the tray bounces light back onto the leaves.

Harvest the outer leaves and they'll keep coming

This is the heart of it. Once leaves are 8–10cm tall, don't pull the whole plant. Take the outer leaves first, using sharp scissors or your thumb and forefinger, leaving the crown and younger centre untouched. For lettuce, twist off individual outer leaves close to the base. For rocket, mizuna and mustard, snip across the whole tray about 2cm above the compost — most will re-sprout two or three times.

Harvest little and often, just before you eat. A handful of leaves straight from the sill into a bowl, dressed with a little oil and vinegar, is one of the small, ridiculous pleasures of cottage gardening. Feed with a weak liquid seaweed tonic after each cut to keep regrowth strong. When a tray finally gives up — usually after three or four cuttings — tip the compost onto the garden, and sow the next pinch. That's the whole art of it: small, frequent, and always something coming on.