Hydroponics is a technology for growing plants in nutrient solutions (water containing fertilizers) with or without the use of an artificial medium (sand, gravel, vermiculite, rockwool, perlite, peatmoss. coir, or sawdust) to provide mechanical support.
Liquidhydroponic systems have no other supporting medium for the plant roots: aggregate systems have a solid medium of support. Hydroponic systems are further categorized as open (i.e. once the nutrient solution is delivered to the plant roots, it is not reused) or closed (i.e. surplus solution is recovered, replenished, and recycled). Hydroponic growing (as opposed to soil growing) allows you to control the nutrient levels for your plants directly. Because of the higher control over nutrients, hydroponically grown plants generally have a much higher yield than similar plants grown in soil.
A plant gets its food source by turning Co2, light and water (or hydrogen) into carbohydrates through a process called photosynthesis. With hydroponics growing, plants are grown without soil so they must get their nutrients from the nutrient solutions added to water. The absence of soil in growing means that hydroponics systems must have some way of supporting the plants while still allowing the bare root system maximum exposure to the nutrient solution. Often a ?growing medium? is used for support and to aid in moisture and nutrient retention in hydroponics growing. Because they lack media to store water and nutrients, water culture systems need a continuous flow of nutrients to prevent drying out the plant roots.