With an overhead system of irrigation it is often an advantage to water after sowing. In the management of crops under glass, the beds are nearly always watered thoroughly after sowing. The usual plan is to try to apply enough water to render further watering unnecessary until germination is complete. The watering of flats or beds by subirrigation is regarded as an advantage by some. The beds must, of course, be water-tight. Flats are often set in shallow tanks containing about inch of water, or more if necessary. The water soon rises in the soil by capillary attraction, and there is no danger of washing out the seed. Watering by sprinkling, however, is always satisfactory when done with care and intelligence.