Where to sow
Sow February to July. Early sowings should be done under glass with a temperature between 15 and 20c. Sow seeds thinly on seed compost and cover with a sprinkling of vermiculite or compost. Later sowings can be done directly where they are to grow in rows 30cm apart.
Prick out seedlings sown under glass and grow on until you're ready to plant out, hardening off first. Plant 30cm apart in rows 30cm apart.
Keep picking the leaves and they'll keep growing. Successional sowing every 2-3 weeks will also help ensure a constant crop.