Salad leaves are the most generous crop you can grow in a small space. They are shallow-rooted, fast, and — crucially — you don't have to wait for them to heart up before eating them. A windowsill tray 15cm deep and 30cm wide will keep one person in leaves through the spring and summer, and two or three 20cm pots on a doorstep or balcony will supply a family. The secret is to grow for leaves rather than whole lettuces, harvesting young and often.

Match your leaves to your light

Before you sow anything, watch your growing spot for a few days. Salad leaves want roughly four to six hours of decent light a day; a south or west-facing windowsill is ideal, while an east-facing one will give you slightly slower, softer growth. A north-facing sill isn't hopeless — rocket, spinach, mizuna and chard will all manage — but expect thinner, leggier plants and be prepared to sow more often.

If you're growing outdoors on a balcony, a yard or a shared courtyard, you'll have more light but also more weather. A spot that gets some shelter from wind is worth more than one that's perfectly sunny, because salad leaves dry out fast and bolt quickly once stressed.

The best varieties for cut-and-come-again picking

Loose-leaf types are made for this job. They regrow from the base after cutting, unlike hearting lettuces, which give you one harvest and then sulk.

• Rocket — wild rocket is slower to bolt and more perennial than the salad type, though both are peppery and quick. Sow it as soon as the weather warms.
• Loose-leaf lettuce — look for 'Salad Bowl', 'Lollo Rossa' and 'Red Salad Bowl', which give you frilly, colourful leaves for months from one sowing.
• Spinach — 'Medania' and similar varieties are excellent for baby leaves, and perpetual spinach (a leaf beet, really) will crop right through winter with a little protection.
• Extras worth a row — mizuna, mustard 'Red Giant', pak choi and rainbow chard all mix beautifully into a cut-and-come-again blend.

Trays, pots and compost that actually work

Depth matters more than width. Aim for at least 12cm of compost for rocket and spinach, and 10cm for lettuce — deeper containers hold moisture and buffer against a hot afternoon. Anything with drainage holes will do: old seed trays, reused mushroom punnets, a lined wooden crate, terracotta pots, or a proper self-watering windowsill planter if you'd rather water less often.

Use a peat-free multipurpose compost with a handful of horticultural grit or perlite mixed through for drainage. Garden soil alone is heavy, compacts in trays and can carry pests and weed seeds, so keep it out of your windowsill pots.

Sowing little and often

The single habit that separates a good supply from a glut is succession sowing. Fill your tray to about 2cm below the rim, firm the compost gently, water it, then scatter seed thinly — roughly 2–3cm apart — and cover with just 5mm of compost. Lettuce needs light to germinate, so barely cover it. Water with a fine rose or a mister to avoid washing seeds into clumps.

Germination takes about seven to fourteen days at 15–18°C. Lettuce germinates poorly in high heat, so in July and August sow in a cooler spot or in light shade, and bring trays indoors if your windowsill bakes. After that, sow a small tray every fortnight from March to September, or start in February and keep going into November on a bright indoor sill.

Watering, feeding and keeping leaves tender

Small containers dry out fast, so check daily in summer — often twice. Irregular watering is what makes leaves bitter and sends plants bolting, so keep the compost consistently moist but never sodden, and water the compost rather than the leaves to reduce mildew. Bottom watering from a saucer works well and keeps foliage dry.

After each cut, give the tray a diluted liquid feed — a general purpose or seaweed feed at half strength is plenty. This is what powers the second, third and fourth regrowth rather than a tired, yellowing flush.

Pests are manageable. Slugs and snails will find outdoor pots, so raise containers onto feet or a gravel layer. Indoors, check the undersides of leaves for aphids and whitefly and squash them early, and give trays some airflow to discourage damping off and downy mildew. If flea beetle riddles your rocket outdoors, a fine insect mesh over a hoop of cane solves it quickly.

Harvesting for months, not weeks

Cut with scissors about 2–3cm above the compost surface, taking the whole tray in one sweep or picking outer leaves from larger plants. Most blends will give you three or four good cuts before they fade. Once a tray slows down, tip the compost into your houseplant mix or a garden bed and sow the next one — a rolling cycle of small trays is far more productive than one big, overcrowded one.

In winter, hardy lettuces such as 'Winter Density', lamb's lettuce and perpetual spinach will crop under fleece in a cold frame or on a sheltered balcony, and a bright kitchen windowsill will keep rocket and spinach going with a little patience. Sow a tray today and you'll be cutting your first leaves within a month.