Sow indoors all year round. If you intend to grow coriander in pots on a windowsill you can sow at any time of year. Sow thinly 0.5cm deep into small pots of compost. Water well and place in warm, light position, away from cold draughts and out of intense, direct sunlight. Keep the compost just moist and be careful not to overwater, the compost should almost dry out before it is watered again. Seedlings should start to appear in approximately 14-21 days but be patient as germination can be slow. If necessary thin out the little seedlings to 2cm apart when they are large enough to handle. If you plan to harvest them as baby leaves, then no thinning is necessary. Once established, a regular liquid feed will help maximise crops.