Coriander seeds are best sown direct, outdoors from May in shallow rows, 20 cm apart, and later thinned to around 7 cm apart. For an early crop, seeds can be sown indoors from March. Also good as an autumn/winter crop sown in September. Germination time is 7-21 days. 
Prepare the area by removing weeds and adding organic matter before planting. Transplant your seedlings into their final growing position in rows 20 cm apart and plants 7 cm apart from May onwards.
Bolting can be a problem in the height of summer. Long day length and hot, dry weather will push coriander to go to seed. Ensure the ground has enough organic matter to retain moisture and keep it well watered. You can also make successive sowings to replace any bolted plants or just let them flower for the bees and enjoy the seeds later in the year.