So the problem is by no means as simple as might at first be supposed. Not only must sufficient plant food be added to the soil but it must be in certain forms, and neither too much nor too little may be given if the best results are to be attained.
Now it is a fact established beyond all dispute that not only food, but air and water, as well, must be supplied to the roots of growing plants; and this being the case, the _mechanical_ condition of the soil in which the plant is to grow has a great deal to do with its success or failure. It must be what is termed a porous and friable soil--that is, one so light and open that water will drain through it without making it a compact, muddy mass. One of the things I noticed about my special fertilizer soil, mentioned above, was that it settled, after being watered, into a solid mass from which water would not drain and into which air could not penetrate.
It is next to impossible to find a soil just right for house plants, so, as a general thing the only way to get a good soil is to mix it yourself. For this purpose several ingredients are used. If you live in a village or suburb, where the following may be procured, your problem is not a difficult one. Take about equal parts of rotted sod, rotted horse manure and leaf-mould from the woods and mix thoroughly and together, adding from one-sixth to one-third, in bulk, of coarse sand. If a considerable quantity of soil will be required during the year, it will be well to have some place, such as a bin or large barrel, in which to keep a supply of each ingredient. The sod should be cut three or four inches thick, and stacked in layers with the grassy sides together, giving an occasional soaking, if the weather is dry, to hasten rotting. The manure should be decomposed under cover, and turned frequently at first to prevent burning out; or sod and manure can be rotted together, stacking them in alternate layers and forking over two or three times after rotting has begun. The manure furnishes plant food to the compost, the rotted sod "body," the leaf-mould water-absorbing qualities, and the sand, drainage qualities.
If the soil is wanted at once, and no rotted sod is to be had, use good garden loam, preferably from some spot which was under clover-sod the year before. If it is difficult to obtain well-rotted manure, street sweepings may be used as a substitute, and old chip-dirt from under the wood pile, or the bottom of the woodshed if it has a dirt floor, will do in place of leaf-mould. Peat, or thoroughly dried and sweetened muck are also good substitutes for leaf-mould. Finely screened coal ashes may take the place of sand.