76 THE PLANTING OF SEEDS 



exact depth of planting in any given case: The seed, the soil, 

 the season. 



Size and Structure of Seed. — In general, the seedlings of 

 vegetables having large seeds have greater power to push their 

 way to the surface of the soil than seedlings of vegetables having 

 small seeds. The structure of the seed and seedUng, irrespective 

 of size, also has some influence upon the ability of the seedling 

 to reach the surface. However, in general, large seeds can safely 

 be planted deeper than small seeds. 



The type and condition of the soil also influence the depth of 

 planting. It is necessary to plant seeds deeper in a sandy than in 

 a clayey soil in order to insure sufficient moisture. The converse 

 also is true: It is necessary to plant seeds shallower in a clayey 

 than in a sandy soil, in order that the seedlings may reach the 

 surface. A sandy soil is loose and open and the surface does not 

 bake into a crust following a rain subsequent to planting, as is 

 the case with a clayey soil. If a heavy rain falls soon after the 

 planting of small seeds in a claj^ey soil, unless the seeds are close 

 enough to the surface so that the seedlings can reach the surface 

 before the crust forms, they are likely not to get through until 

 another rain softens the crust. ' If that is too long delayed they 

 may perish in the meantime. In general, the looser and the more 

 friable the soil, whether this condition is due to the presence of 

 sand or of humus, the deeper the seeds may be planted; and the 

 deeper they are planted the surer they are of having plenty of 

 moisture for germination. 



The more thoroughly prepared the seed bed, the shallower it 

 is possible to plant seeds and yet have them supplied with suffi- 

 cient moisture for germination. This is because capillary action 

 is much more perfect in such a seed bed. In a poorly prepared 

 seed bed on clayey ground, the soil is sometimes so lumpy that it 

 is necessary to plant the seed so deep in order to secure moisture 

 that, in the event of subsequent rains and crust formation, the 

 seedlings are unable to penetrate to the surface. The seed bed 

 in clayey soil should be sufficiently well prepared to make shallow 

 planting possible. 



Under greenhouse conditions it is possible to plant seeds very 

 shallow, since the soil of the seed bed can be sifted and the moisture 

 supply is under complete control. Water can be applied whenever 

 necessary and evaporation prevented by covering the seed flat 

 with a newspaper or a pane of glass. It is thus possible to grow 



