Governments have been willing to certify that hydroponically grown tomatoes are safe to eat. They contain the same nutrients as tomatoes grown other ways. The same governments have been less willing to label these tomatoes as organic. One reason for this is the basic test of organically grown fruits and vegetables. The soil must be certified as organic. Because hydroponics uses no soil, it cannot pass this particular test. This may not be the only reason for the lack of certification. Growing plants hydroponically can take a great deal of energy. This may also be part of the problem with labeling.
Hydroponics is the science of growing fruits and vegetables without soil. Plants are grown in beds that contain solid substances for the plant roots. Some growers prefer to use gravel, but plastic and metal stands have also been used. On a regular basis, these plants are flooded with nutrient rich water. The plants get all their nourishment through the water as their roots soak it up. Any leftover water is generally recycled into the system where more nutrients are added for the next soaking.
There is no evidence that plants cannot be given organic nutrients and fertilizers using this method. One point in favor of hydroponics is the ability to regulate nutrients the plants get. If the grower does not add it to the water, then the plant will not receive it. Opponents are quick to point out that no one knows if there are any unknown nutrients plants receive from soil. Research is still being done on this factor.
One stumbling block for labeling hydroponics as organic is the energy used to produce them. Greenhouses depend on sunlight for heating and soil to grow the plants. Hydroponics is a very controlled environment. Instead of using sunlight to keep plants warm, growers prefer to artificially heat their buildings. Sunlight is allowed in, but it is not necessary to warm the plants. Environmentally, hydroponics uses less water than soil based growing, and that factor makes them more sustainable. The heating resources are not necessarily a sustainable factor, and they are helping to keep the organic label off hydroponically grown tomatoes.