8 HORTICULTURAL MANUAL. 



commercial seeds the dish test, carried on to perfect leaf- 

 development, is often a time- and money-saving process. 



9. Depth of Planting Seeds. As a rule, the depth of 

 planting depends on the size of seeds. But this is not 

 invariable. Some quite large seeds, such as those of the 

 bean, castor-oil bean, and some of the nuts, send out thick, 

 clumsy seed-leaves, and if planted three inches deep, fol- 

 lowed by slight soil-baking, they are unable to force their 

 way upward. This quite numerous class, including the 

 pumpkin and squash, should not be covered more than an 

 inch deep, and in heavy soils still less. On the other hand, 

 such plants as leave the seed-leaves or cotyledons in the 

 soil, such as corn and the pea, will bear deep planting if 

 the soil is not too compact to admit air freely. The close- 

 observing horticultural student will soon notice that some 

 plants, such as bean, pumpkin, and the orchard-fruit 

 seeds, when germinating lift up the seed-leaves bodily into 

 the air, while in others the seed-leaves remain in the soil. 

 If deeply planted, the clumsy leaves may fail to lift the 

 compact covering, while in such as corn and peas the 

 seed-leaves do not emerge, but growth takes place upward 

 from a growing point or plumule (Fig. 1). All fruit-tree 

 seeds should be planted early, and planted no deeper than 

 is necessary to secure the needed moisture. Even where 

 small-fruit seeds are planted on the surface and pressed 

 down firmly with a board early in the spring, they usually 

 start the root downward in time to escape injury by drying. 

 But it is safer to press down such seeds and cover with a 

 board or mulch to lessen evaporation while the roots are 

 starting. When the first upward growth is observed the 

 covering is removed. 



. In planting nuts it is best to follow Nature as closely 

 as possible. Plant shallow not more than an inch deep 

 and press the soil down firmly. In early spring plant- 



