The presence of enough moisture to keep the seed thoroughly soaked.

The presence of fresh air.

The presence of more or less heat.

This teaches us that when we plant seeds in the window box or in the garden or on the farm we must so prepare the soil and so plant the seeds that they will be able to obtain sufficient moisture, heat, and air for sprouting.  The moisture must be film water, for if it is free water or capillary water filling the soil pores, there can be no ventilation and, therefore, no sprouting.

SEED TESTING

In a previous experiment (page 73) the seeds planted in the wet clay did not sprout (see Fig. 38).  In answer to the question, “Why is this?” some will say the seeds were bad.  It often happens on the farm that the seeds do not sprout well and the farmer accuses the seedsman of selling him poor seed, but does not think that he himself may be the cause of the failure by not putting the seeds under the proper conditions for sprouting.  How can we tell whether or not our seeds will sprout if properly planted?  We can test them by putting a number of seeds from each package under proper conditions of moisture, heat and air, as follows: 

For large seeds take two plates (see Fig. 39) and a piece of cloth as wide as the bottom of the plate and twice as long.  Count out fifty or one hundred seeds from a package, wet the cloth and wring it out.  Place one end of the cloth on the plate, place the seeds on the cloth and fold the other end of the cloth over them.  On a slip of paper mark the number of seeds and date, and place on the edge of the plate.  Now cover the whole with another plate, or with a pane of glass to keep from drying.  Set the plate of seeds in a warm room and examine occasionally for several days.  If the cloth tends to dry, moisten it from time to time.  As the seeds sprout take them out and keep a record of them.  Or leave them in the plate and after four or five days count those that have sprouted.  This will give the proportion of good seeds in the packages.

For small seeds fold the cloth first and place the seeds on top of it.

Another good tester for small seeds is made by running about an inch of freshly mixed plaster of Paris into a small dish or pan and moulding flat cavities in the surface by setting bottles into it.  The dish or pan and bottles should be slightly greased to prevent the plaster sticking to them.  When the cast has hardened it should be turned out of the mould and set in a large dish or pan.  One hundred small seeds are then counted out and put into one of the cavities, others are put into the other cavities.  Water is then poured into the pan till it rises half way up the side of the plaster cast or porous saucer.  The whole thing is then covered to keep in the moisture (Fig. 40).

Another method is to get boxes of finely pulverized sand or soil and carefully plant in it fifty or one hundred seeds of each kind to be tested.  Then by counting those that come up, the proportion of good seeds can easily be found.