- Early indoor sowings in pots or trays under glass. Thin to 5-6cm (2-2.5”) apart before gradually hardening off and planting out in April 25cm (10”) apart.Later sowings direct into the growing site 1cm (0.5”) deep. Gradually thin to eventual spacing 25cm (102). The thinnings can be potted for winter use. Always harvest by cutting 2cm (¾”) above the soil to encourage new growth.