Anethum graveolens Direct seed in full sun in spring as soon as soil can be worked. Sow seed .6 cm deep, 10 seeds per 30 cm of row and cover lightly with soil. Thin to 10 cm. for strong, full plants. Sow every 3 weeks for a steady supply of fresh dill weed. Seed heads can be harvested when seeds begin to dry and turn light brown.