How to grow salad leaves year-round on a UK windowsill

Setting up

A south or south-west facing windowsill works best. East and west-facing sills do fine in summer but produce thin, leggy plants from November to February.

You'll need:

• 4 shallow trays (30 × 20 × 6cm) with drainage holes
• A drip tray for each
• A 5L bag of peat-free seed compost
• Seed packets: mizuna, rocket, mustard 'Red Frills', pea shoots, mixed Italian salad

Cost: around £15 of kit, £8 of seed. That lot lasts 8 months of cutting.

Which varieties work, month by month?

Winter (Nov–Feb). Low light, cool indoor temperatures:

• Mizuna. Feathery, mild, regrows fast
• Mustard 'Red Frills'. Pepper-bite, beautiful colour
• Rocket 'Wild'. Slower, but reliable in low light
• Winter purslane (claytonia). Succulent, surprisingly hardy
• Pea shoots. Sweet, fast (7–10 days to first cut)

Summer (Apr–Oct). Add:

• Mixed loose-leaf lettuce ('Lollo Rossa', 'Salad Bowl')
• Basil (in its own pot. It wants different watering)
• Coriander. Resow often, it bolts fast indoors
• Spinach 'baby'. Three cuts before it flowers

The 10-day sowing rotation

1. 1

   Day 1: sow tray 1

   Fill the tray with compost, level it, press the seed in (don't bury deep, 5mm cover max), water from below, and label.

2. 2

   Day 10: sow tray 2

   Tray 1 is germinating; tray 2 starts the next wave.

3. 3

   Day 20: sow tray 3

   Tray 1 ready to cut; tray 2 growing; tray 3 sown.

4. 4

   Day 30: sow tray 4 + recut tray 1

   Full rotation now in motion. Tray 1 has had its first cut and is regrowing.

5. 5

   Day 40: discard tray 1, sow new tray 1

   After three cuts, tray 1 is spent. Tip it into the compost heap, refill with fresh compost, and sow again.

Once it's up and running, the system more or less runs itself: every 10 days you sow one tray and cut from another. A five-minute Sunday job turns into 4–5 portions of salad a week.

Watering and light

Water from below. Sit the tray in 1cm of water for 10 minutes, then lift it out to drain. Watering from above compacts the surface and dislodges the tiny seedlings.

In December and January, rotate the trays 180° every other day. Without it, the leaves lean towards the glass and the stems lengthen weakly.

What this actually saves you

A bag of supermarket "wild rocket" costs £1.50 for 80g. A windowsill tray of rocket gives you 60g per cut, three cuts before resowing, roughly £3.50 of salad per tray, every 40 days. Run four trays year-round and you're growing the equivalent of around £130 of supermarket salad a year, fresher, with no plastic, in less floor space than a microwave.

The windowsill is the most under-used growing space in British homes. A tray sown today is salad on the plate in three weeks.