Requisites for proper plant growth are warmth, ventilation, root room, the absence of harmful alkalies or animals that destroy the beneficial bacteria in the soil, water and plant food.
By far the most important requisite for growth is water. More plants and crops fail because of the lack of a proper amount of it than from any other cause.
Plenty of fresh air is needed by the plants, as they derive a portion of their food from it.
They adapt themselves largely to conditions as to root-room, a plant thriving in a pot, but spreading to much greater root space when grown in the open with plenty of room. The more restricted the root space, the more food and water it will require.
The fourth requisite for growth does not concern us as there are no alkali lands in the counties near the Twin Cities, and the harmful minute animals that destroy the beneficial bacteria in the soil are as a rule found only in greenhouses.
The best fertilizer for the garden is the thorough use of the hose.
Each year stable manures become harder to obtain, but the fertility of the garden can be maintained by the use of commercial fertilizers, which are more concentrated foods and are much easier to work with.
The perfect plant food consists of nitrogen, phosphorus and potash. We can obtain these in separate form and use as we need them.
Nitrogen comes in the form of a salt, called nitrate of soda, and in dried blood. The nitrate of soda is very soluble in water and is taken up at once by the plant. It can be scattered upon the ground near but not touching the plant, as in the latter case it would burn it. It can also be dissolved in water—a tablespoonful to a pail—and the ground, but not the plant, watered. Dried blood is slower in action and requires warmth, so should not be used early in the season. Nitrogen promotes quick and luxuriant growth of leaves and stems and is good to use when a green growth of any kind is wished.
In bone meal we find the phosphorus necessary to aid in the development of fine and many flowers, to expand root growth and to hasten maturity. It works slowly, so can be applied to the ground about a plant early in the season, and will be available in the ground the following year if enough is used. Equal parts of nitrate and bone meal can be used at the rate of one to two pounds to every one hundred square feet.