The garden yard

Plants need water, air, food, light and warmth just as animals do, and it is wonderful to study the shifts and contrivances to which they resort to get these, and also to protect themselves against too much of any of them. If the plant were not able to change itself to suit the conditions, it would often die where now it fights successfully.

Nothing affects the plant like the water supply; the size of every part of the plant is increased by plenty of water. It not only helps the growth of flowers and fruits, but it even changes the character of the plant. In a moist air, cactus will put out leaf-like organs, gorse will grow leaves instead of thorns; while where the water supply is very scanty, the potato will put forth no leaves, but will become like a cactus.

Yet plants do not grow in soil that is too wet, because they need air, and too much water suffocates the roots. By proper irrigation—which means giving just the right supply of water—both the quantity and quality of the crop can be improved.

While plants need light, all varieties do not need the same amount of it. You will find that those which need much light can turn towards it, and this of itself will show you where such plants should be sown. Plants have various ways to resist the supply of light when they are getting too much. They droop their heads or close their leaves, which prevents evaporation.

Different plants need different food and the same soil conditions will not suit all. Some require rich soil if they are to flourish, while some do better in poor soil. On the whole, plants, like people, are better for under-feeding than for over-feeding. In general, starving a plant makes it flower and fruit more quickly, but less abundantly; while over-feeding helps to make much stem and leaf instead of fruit, and also produces monstrosities. Too much nitrogen, especially, makes too much stem and leaf, though nitrogen is one of the most important plant foods. (Bailey says too much nitrogen can be corrected to a certain extent, by potassium put in the soil.⁠[3])

We are sure of only three plant foods—potash, phosphoric acid, and nitrogen. Then there are lime, stable manure, green manure, clover and cowpeas to doctor the soil with, when it is suffering from chemical ills. This gives some idea of the vast unexplored regions of agriculture which afford you and every other worker in the soil an opportunity to make some great discovery for the benefit of the world. No other calling offers such limitless opportunities.

Lime is especially valuable for plant food and also to make other kinds of plant food available. Crops often fail in soil where there is plenty of plant food, because it is not in the form that the plants can use. Lime hastens the decay of vegetable matter, sweetens sour soil, and greatly improves the texture of clay soils. Besides this it counteracts magnesium in the soil and destroys its bad effects. But lime may not be applied carelessly, because, although some plants cannot live without it, some require a very small quantity. (It is, therefore, wise to send a sample of the soil, to write what we want to grow, to the nearest Government experiment station, who will probably suggest what could be done with it, to make it productive.)

The right degree of warmth is another plant necessity. The best temperature for plants generally is 86° of the ordinary thermometer (30° Centigrade). This, however, depends upon the plant. The “best temperature” varies with the species and variety. Usually, if the soil is hotter than that, growth stops, and if the greater heat is kept up, the plant dies. When the temperature is lowered, growth ceases before freezing point is reached. Some few plants may be frozen without injury if they are allowed to thaw slowly, but most of them are easily killed by the frost. Too great heat or too much cold acts the same as lack of water; the heat causes too great evaporation, the cold prevents the roots taking in the water.

Shingles stuck in the ground on the sunny side will serve to protect young plants from sun and rain, while cool soil may be had by using the shady places, or by sheltering the ground with flat sheds the roof boards of which have open spaces between them as wide as the boards. This is done in some southern tobacco fields.

It is the law of nature that living cells must have a constant supply of oxygen, that is why a tar wash sometimes kills plants by cutting off the air supply. In the same way, too wet soil or too hard a crust smothers the roots and the plants die. The surface soil should be kept loose and sufficiently dry, so that the air can circulate. If this be prevented, the soil becomes hard and sour and unfit to feed plants.

It is of the greatest importance to keep the soil open and loose by proper tillage, so as to make plants healthy and vigorous.

Though plants need air they should be protected from draughts and sudden blasts of air, whether hot or cold. For this reason, the intelligent gardener will consider the effect of wind upon his crops and where necessary will plant windbreaks. If you look about you, you cannot fail to see the ill effects of strong winds in the odd shapes of forest trees; and in badly arranged gardens you will find the same effects in the fruit trees and small fruit bushes and in the stunted crops. Plants shape themselves to their surroundings, and the way they shape themselves is determined by inherited qualities; so it may be said that the success of the plant depends upon its surroundings and upon the seed it came from.