"The depth depends upon the size of the seed. Take such small seed as poppy, parsley, even lettuce, and these may be just sprinkled on the surface of the ground. Then tread them in with the foot or place a board over them and walk on the board. In this way the small seed are pressed into the soil quite sufficiently.
"For seeds in general the following might answer for a rule: There are seeds like corn, oats, wheat and the grasses which come up unhampered by their seed leaves. Such seed may be planted deeply—say ten times the thickness of the seed. Other seed like beans, squash, radish, etc., push and carry their seed leaves up through the soil with them. So these, because of this extra work, should be planted nearer the surface. Four or five times the thickness of the seed is a safe rule to follow.
"When the seed becomes entirely or nearly saturated with water then germination begins. Sometimes people soak their corn in tepid water before planting. This hastens germination. But on the other hand if the soil is very wet and cold the soaked seeds may rot in so much moisture. Certain seeds have very thick coverings. Canna, date and nut seeds are examples. Their cases are so hard and absorb moisture so slowly that germination is a long process. To hasten this little holes may be drilled in the case, thus giving the plant germ a chance to get out. Nurserymen crack the nuts in order to help matters along. You can readily see what a really difficult piece of work it is for a tiny embryo or baby plant to break open a thick case.
"If seeds are planted too deeply again, a tremendous piece of work is imposed upon the little plant. To push up through, say one inch of soil, would be quite a task for a lettuce seedling.
"Finally in seed planting, the soil must be safely compacted or pressed about the seed. The object of this is to bring in contact with all parts of the seed soil particles with their films of water. Suppose a radish seed is planted and no soil happens to come in direct contact with the seed. That distance, so slight to us, is a well-nigh impossible one for the rootlets to extend to.
"There is a possibility of course, of too close compacting. This occurs when the soil is very wet. Do not compact at all then. In fact, such soil condition represents a very bad time for planting, anyway. Moisture is necessary for germination, but superabundance of water is fatal. It is simply ideal when after a planting a gentle rain comes—germination.
"I remember once seeing a garden which school children had planted so close to the surface that after a rain most of the seeds were lying all sprouted on the surface of the soil. Take care not to plant in such a manner.
"This talk has been largely for the purpose of bringing to your minds certain necessary points. Let me sum them up: Cheap seed are expensive because they are often full of impurities and lack vital power. Buy good seed and test them. Plant large seed, because the storage of food is greater. Make the soil conditions right in order to give every help to the seed. Plant neither too deep, nor too near the surface. Compact the soil, and so aid germination. The first start of work must be right; otherwise, trouble comes."