Chapter 5 - Fertilizers And Plant Foods

When we talk about fertilizers and plant foods, we're really talking about the same thing. Plant foods provide the same nutrients to the soil as do manure and other fertilizers, but in concentrated form.

Like any other living thing your house plants must absorb foods in order to live and grow. The foods they take in come in two forms and from two sources, 1) from the air in the form of gasses which are "breathed" in by the foliage, the most important gas to plants being carbon dioxide. 2) from the earth in the form of soluble minerals which are absorbed with water by the roots. There is not much we can do about the constituents of the air, but we can control to some extent, the chemical and mineral make-up of the soil.

No matter how good the soil is you use in your pots, it is inevitable that sooner or later it is going to need some supplements to do a proper job of feeding your plants. Soil out in the open is replenished year after year with decaying vegetable matter, shifting topsoil, and natural fertilizers; but your potting soil, isolated as it is indoors, has no chance for natural replenishment. This is where fertilizers and plant foods come into the picture.

The function of the fertilizer and the plant food is to put back into the soil those mineral nutrients which have been depleted by constant use. Although all soils are made up of hundreds of ingredients, the ones most necessary for growth are nitrogen, phosphoric acid, and potash. These ingredients are to be found in varying degrees in all organic animal manure and, of course, to a much more important degree in commercial plant foods.

Organic Fertilizers Manure

Manure, especially that of domestic animals, cows, sheep and chickens, is the oldest fertilizing agent known to man and has been used to help plants grow ever since the first farmer cultivated his crops. The problems involved with using manure as a fertilizer on house plants are pretty much the same as those discussed in the previous chapter on potting soil; it is bulky, difficult to store, and has a smell that many people find extremely offensive. Further, it is not particularly efficient in the small doses required by the space limitations in a house plant garden. Due to its unconcentrated form large quantities are needed and must be worked into the soil by hand. Many people recommend that the home gardener use as his feeding agent liquid manure. This is a solution made by steeping a bag of cow manure in water. The mineral nutrients contained in the manure are dissolved in the water, and the result is a strong solution, which can be diluted with water and used to feed the plants. Here again, most people will have the problem of providing space (here, too, a cellar or barn seems to us the only answer) and taking the time needed to make this concoction. We feel that the solution for most people is to be found in commercially prepared plant foods.

Plant Foods

Plant foods which as we have said are commercially prepared additives designed to replenish soil depleted by constant use, are made in tablet and powder form. They are soluble in water and are fed to the plants in liquid form. These plant foods offer the householder many advantages over the use of manure or manure distillations. In the first place, they are odorless, and take up a minimum of space. Then they are scientifically prepared, and come with specific instructions on how and when to use them. Here again, as with soils, we feel there is no advantage in attempting to concoct what will unfortunately always be inferior to a good commercial product which is readily available.

When to Feed Your Plants

Generally the plant you buy already potted, should be able to get along without extra nutrients for at least a month or so. If it fails to prosper, showing signs of distress (lackluster and curling leaves, prematurely falling flowers, etc.) before that time, it is probable that the difficulty lies not in the lack of food, but in the plant itself, or in the environment you have provided. If after a month the plant continues unthrifty, then by all means try feeding it. Remember, when you use a plant food, that the method outlined in the instructions on the package have been developed as the result of long experience. Follow them exactly. It is a natural tendency to feel that if one tablespoon will be beneficial, then two will be twice as effective. Don't let yourself make this mistake. Excessive feedings of plant food may easily burn the roots and kill the plant.

While we must be careful not to overfeed, we must also realize that plant food is a necessity, and should be fed at intervals in the proper amounts to all plants, especially those that must remain pot bound over a long period of time. One way to ascertain whether a plant is in need of feeding is to look at the roots. To do this you hold the plant upside down with one hand covering the earth, and with the plant stem between the second and third fingers. With the other hand you lift the pot. You may have to give it a couple of taps with a mallet to loosen the earth from the inside. Inspect the ball of earth, and if the roots are thick, completely encasing the earth ball, then the plant should have regular feedings. If the ball looks as though it is entirely made up of roots, with little or no earth showing, then it is time to repot. (See the discussion of potting and repotting in Chapter 6.) Another point to remember is that flowering plants usually need more food than foliage plants.

In your supply store you will find commercially packaged foods which are effective for almost every variety of house plant. There are a few plants such as Roses and African Violets whose makeup is such that they need special foods. These too are readily available, and should be used instead of the general purpose foods.

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