Some soils dry out more rapidly than others, and some.

Fig. 30. lath screen seeds must have a more uniform supply of moisture than others.For these reasons shading is often an advantage. In outdoor culture, lath screens (Figure 30) are frequently used. Just half the space is covered by the lath, so that no part of the bed is shaded all the time. A screen of this kind is easy to handle and provides good ventilation. Old carpet, burlap and paper are often used in shading beds. The screen or shade should always be removed before the young plants are injured. In greenhouse and hotbed work the seed boxes are often covered with glass, which conserves the moisture and also raises the temperature when there is sunshine.