Nutrients supply plants with the chemical elements they need for their vital biochemical processes. Nitrogen (N), phosphorus (P) and potassium (K) are the top three generally listed, but there are more than a dozen others. Iron, calcium, magnesium and a host of others are used to help feed hydroponic plants, much like with a soil-based garden.
Nitrogen is used by growing leaves. But despite the fact that the air is about 79% nitrogen, plants need it in the form of a supplement. This is due to the fact that the nitrogen molecules in our air (N2) are too stable for plants to break them down. Phosphorus is essential to root growth. And lastly, potassium helps plants resist disease by stimulating enzyme formations.
The other elements perform a variety of functions. Calcium, for example, is a large component of cell walls and also helps deliver ions to various parts of the plant. Chlorine makes up chlorophyll, which plants use in photosynthesis. And Iron helps make up the hemoglobin molecule, which, like animals, helps to transport oxygen needed for cellular respiration.
If you’re just starting out, there are pre-made solutions available which contain all the essential nutrients and are very easy to work with, provided of course you are careful about dosage. For very young plants, such as small cuttings or those that are just germinating, 1/3 teaspoon of calcium nitrate dissolved in a gallon of water is about right, for example. Flowering plants generally require a slightly higher dose.
Other factors, like temperature and water, are crucial factors when it comes to feeding. Both the solution and water should generally be kept at room temperature with most hydroponic gardens.
Nutrient feeding with dry plants should generally be avoided as nitrogen burning may occur. This usually doesn’t occur with hydroponics , but is possible with something called “aeroponics” where plants are grown in the air.
Allowing any water to stand overnight will help evaporate any excess chlorine from home water sources. Mineralized or distilled water makes things easier as it will already contain some useful elements.
You should monitor pH levels and try to keep it as neutral as possible because as plants absorb the nutrients the water will become more alkaline. This alkaline can be counteracted by adding small amounts of sulfuric acid, or in extreme cases, adding sodium hydroxide. Testing kits are available to accurately measure the pH of your hydroponic water.
Generally speaking, plants grown with hydroponics will be more sensitive with nutrient levels and are not as resilient as plants grown in soil. In a soil garden plants can absorb or shed compounds. With hydroponics, compounds are shed into the water supply, which doesn’t move them away from the plant. The hydroponic gardener will need to exercise more care to keep plants healthy.
