Lettuce seeds can be sown in modules, seed trays or direct into the growing site and thinned to the required spacings as soon as possible. Rows should be about 30cm apart and the seed down 1cm deep. Small lettuces can be spaced at 15-20cm distances, whilst large crispheads will need 30-35cm. Regular watering is essential especially the 7-10 days before maturity. Lettuces mature quickly, butterheads at about 10 weeks and crispheads and cos types at around 14 weeks. They will not stand for more than 5-7 days once mature before running to seed, so successional sowing or the use of the "cut and come again" types is required. Sowings begin in February under glass at 15 degree celsius followed by outdoor sowings under cloches until late autumn sowings for overwinter production using cloches and glasshouse. Germination difficulties may be experienced in July and August as lettuce seed will go into dormancy if sown in very hot weather.