All plants need nutrients to supply them with the elements needed for 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.
Though nitrogen makes up about 79% of the air we breathe, plants require it as a supplement as it promotes leaf growth. The N2 molecule in air is very stable and plants don’t break it apart to use single nitrogen atoms. Phosphorus helps to promote root growth. Potassium aids in disease resistance owing to its role in enzyme formation.
Other elements help plant with performing some of their other functions. For example, Calcium help delivery of ions to various parts of the plant and makes up part of the cell walls. Chlorine makes up chlorophyll, which plants use in photosynthesis. Iron is essential to the hemoglobin molecule, which is formed by plants as well as animals, where it helps transport oxygen needed for cellular respiration.
Pre-made solutions are the easiest to work with to supply all the needed elements. As with any compound, dosage is important. 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. Any solution should be fed at room temperature, which should also be the temperature of any water used in hydroponic gardens.
Dry plants should not be fed nutrients. Nitrogen burning is possible. That’s rarely a problem with hydroponics , but one ‘branch’ known as aeroponics, where the plants are grown in air, can suffer that problem.
Setting the tap water you plan to use with your plants to sit overnight will help evaporate excess chlorine, as chlorine evaporates more quickly than water does at room temperature. Mineralized water is preferable to distilled since it will contain calcium and other 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. A testing kit will help, as it will allow you to precisely measure pH levels.
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. Releasing compounds into the water medium doesn’t move them away from the plant. This simply means the hydroponic gardener needs to be a bit more careful to maintain a healthy crop.
