Chapter Five: Important aspects of hydroponic growing

Oxygen

Having introduced you to the nutrient solutions used when growing plants hydroponically, we can now return to our simple example of seedlings growing on blotting paper in a saucer of water. This will introduce some new concepts. Normally the new plants would die once the small quantities of nutrients in the water and those dissolved from the blotting paper had been used up. By adding a suitably small quantity of one of the nutrient mixtures available we could prolong the life of these plants.

You can get a variety of plants growing once you dissolve some nutrients into the water you want to grow them in. For example the top of a carrot can be made to produce new green shoots and flower cuttings will often develop new root growth. However eventually all of these plants will die. This time the cause will not be the deficiency of one or more of the nutrient elements, but the lack of an equally important ingredient, oxygen!

The root structure of a plant needs oxygen if it is to remain in a healthy growing condition. The water in the saucer would have had some oxygen in it, enough to allow the plant to grow for a while, however, the water would have become depleted of oxygen quickly turning stagnant. Plants in the soil would also die if the oxygen which permeates through the soil to their root structures, were not available.

Worms are valuable in the garden because while dragging decaying organic matter underground they form small tunnels which allow more oxygen into the soil. That is why plants will grow well in a light, well cultivated soil. Plants will often die if the soil is over watered, making it heavy and cutting off the oxygen supply to the plant’s roots.

All hydroponic systems therefore, have to include some way of introducing oxygen to the plant’s root structure. Keep this in mind, it is very important. A number of different methods for bringing oxygen into hydroponic systems are described later in the book. One simple way is to use a small air pump of the type used in goldfish tanks. The air pump is plugged into a normal power point and the plastic hose running from the pump is placed into your solution of water and nutrient elements. Air is bubbled into your nutrient mixture for the benefit of the plant’s roots in the same way as it is bubbled into an aquarium for the benefit of the goldfish.