Plants grown in soil draw all of their nutrient needs from the earth, and natural processes such as decay and microbial activity constantly replenish the nutrients they need. In a hydroponic system, you must provide for all of the plant's needs. Nutrition is one of the most vital considerations, and your nutrient solution must meet all of the plant's nutritional requirements to have success with your hydroponic garden.
According to Ruth Sorenson and Diane Relf of the Virginia Cooperative Extension, the nutrient solution is the most important factor when growing hydroponic plants. Hydroponic nutrient solution meets plants' needs beyond what ordinary fertilizer provides. Plants require 13 mineral elements that are ordinarily taken from the soil and support all aspects of the plants' life functions. In a hydroponic system, you must provide those minerals as part of the nutrient solution.
Specially mixed nutrient solutions intended for use in hydroponic systems can be purchased online or from specialty garden stores. The HydroponicsOnline website also notes that hydroponic gardeners can mix their own nutrient solutions. Care needs to be taken, however, so that you're certain that you are providing adequate proportions of the correct nutrients.
Sorenson and Relf remind hydroponic gardeners that hydroponic nutrition requires more than dumping a bag of ordinary plant food into the hydroponic system. The HydroponicsOnline website estimates that proportions should be within 5 percent accuracy, adding that nutrient deficiencies and excesses affect hydroponic gardens worse than regular gardens because the solution is the only source of nutrients and natural processes, such as leaching, do not remove potentially toxic quantities. Plants at different stages of growth and different species of plants also have slightly different nutrient needs.
Because nutrient levels are essential to hydroponics success, the HydroponicsOnline website recommends testing your nutrient solution daily to be sure that it is providing enough nutrition for your plants. An electrical conductivity meter shows how easily an electrical current moves through a solution. The higher the reading, the higher the nutrient level. EC readings can be used to easily establish correct concentrations for plants' varying needs.
As plants use nutrients and water evaporates from the system, salts are left behind that could cause potential problems, such as root burn, with your plants. Sorenson and Relf recommend monitoring and keeping water levels consistent, always adding water only, never new nutrient solution. Nutrient solution should be changed every two weeks and the growing medium flushed to clear it of salts.