Wait until late spring or even early summer to avoid fluctuations in temperature which will make your fennel run to seed early. Choose a sunny, sheltered site with fertile, well-drained soil. Sow direct where it is to grow, into shallow drills about 1cm (0.5in) deep.
Thin seedlings to 20cm (8in) apart, keep well watered, and protect against slugs. Earthing up stems as they swell blanches them and adds extra sweetness to the flavour.
Keep the area moist until seedlings emerge, then thin them to allow space for plants to develop strong stems and foliage.