Hydroponic growing means growing in water, without the use of soil. Seeds are germinated in special substrates such as rockwool cubes that are placed into special holders that allow the roots to hangfreely into a nutrient solution. This solution is constantly recyclulated around the system ensuring plants have all they need at all times. The farmer monitors what the plants take up, and makes sure there is the perfect supply of everything the plants need.

It is a closed system, so all the solution that is in the system stays in the system. No water or nutrients are leaking out into the environment, making it an environmentally friendly and sustainable method of growing all kinds of vegetables.

As there is no soil, specially formulated hydroponic nutrient has to be used. This is a mineral nutrient solution, containing all the minerals the plants need to grow such as nitrogen, phosphorus, sulphur, potassium, calcium and magnesium. It also contains the necessary trace elements boron, copper, zinc, molybdenum, iron and manganese. Organic fertiliser can not be used in hydroponics as plants can not take up the organic molecules. Organic fertilisers work in soil, as in soil there are bacteria and fungi that chemically break down the organics into the minerals the plants can take up.

Nevertheless, organic hydroponic is definitely possible (note the two meanings of "organic": when it comes to fertilisers it has the meaning of "organic" as in "chemistry", when it comes to "organic growing" it has the meaning of sustainability, not using chemical pesticides, low food miles, etc). It depends on your definition of "organic", and what you consider the important parts of it. Hydroponics does tick all the boxes for sustainability and low environmental impact, the only reason many organic certification companies nowadays will not certify hydroponic growing as organic is the lack of use of soil.