Hydroponic plants make very special demands on substrate and fertilizer. Anyone who pots their hydroponic plants properly and adheres to the watering and fertilizing rules will be rewarded with easy-care, lush plants.
Hydroponics basically means nothing more than “pulled in water”. In contrast to the usual cultivation of indoor plants in potting soil, hydroponics rely on a soil-free root environment. The balls or stones only serve the plants as a holding space for the roots and a transport route for the water. This has several advantages: Hydroponic plants do not have to be repotted as often. Instead of replacing the entire earth, it is sufficient to renew the upper substrate layer from time to time. The water level indicator enables precise irrigation.
For allergy sufferers, the hydroponic substrate is the perfect alternative to potting soil, as the clay granulate does not mold and does not spread germs in the room. The pollution and pest pollution is significantly lower with hydroponic plants. Weeds cannot establish themselves in the clay granulate. Finally, hydroponic can be reused in the garden practically endlessly without any loss.
The right substrate for hydroponics
For plants to grow well without soil in the pot, a good hydroponic substrate is required. This should be particularly structurally stable so that it supports the transport of oxygen, nutrients, and water to the plant roots over many years without collapsing or condensing. The hydroponic substrate must not rot or rot. Hydroponic substrates, which are usually composed of a mineral mixture, must not give off any aggressive substances to the plants or change their chemical composition in connection with water or fertilizer. The size of the individual pieces of the substrate should be adapted to the root structure of the plants. The total weight of the substrate should be high enough that even large plants find sufficient support and do not tip over.
Many plants can do without soil in the right nutrient solution. The substrate is used for stability and drainage
Types of hydroponic substrates
The best known and cheapest substrate for hydroponics is expanded clay. These small clay balls are burned over high heat, which causes them to puff up like popcorn. In this way, many pores are created inside, which makes the clay balls light and easy to grip. Caution: It is a mistake to say that expanded clay stores water! The small red spheres are permeable to water and do not store the liquid. Due to its pores, expanded clay has a good capillary effect, which means that the plant roots can virtually suck water and fertilizer through. This is what makes expanded clay so valuable as drainage.
The ceramics, which is also made of fired clay, is made porous in a special process so that the angular particles absorb water like a sponge. This substrate stores water and releases it back to the plant roots as needed. Therefore, the pouring and care instructions for both clay granules differ from each other. Seramis is therefore NOT a hydroponic substrate in the strict sense, but an independent planting system.
In addition to the classic clay granules, lava fragments and expanded slate have also established themselves, particularly for the hydroponics of large and outdoor plants. Tip: If you want to hydroponic your plants right from the start, you can already pull cuttings without soil. Since the plants and their roots are still very small when they are grown, you should use very fine granules such as broken expanded clay, perlite, or vermiculite.
Due to its fine grain size, vermiculite is suitable for hydroponic cultivation – here roses
Fertilize hydroponic plants
The professional hydroponic gardener does not speak of “water” when caring for the plants in the granulate, but rather of “nutrient solution”. The simple reason for this is that, in contrast to potting soil, the clay or rock granulate hardly contain any nutrients available to plants. Regular fertilization of hydroponic plants is therefore essential. Only high-quality liquid fertilizers are suitable for fertilizing hydroponic plants, which are added every time the planter is refilled. When buying, make sure that the fertilizer is suitable for hydroponics and that it is tailored to the needs of your plant.
Good hydroponic fertilizer is completely water-soluble and free of substances that are deposited in the substrate (for example certain salts). Danger! Do not use organic fertilizers to fertilize your hydroponics! The organic substances contained in it cannot be converted into the granulate. They are deposited and lead to the fungal growth of the granulate and unpleasant smells.
Ion exchange fertilizers or salt fertilizer systems that are also suitable for hydroponics are reserved for professionals and are usually too complex for home use.
Tip: Rinse the hydroponic plants and the substrate in the plant pot vigorously at least once a year to remove waste and deposits of the nutrient solution. This will prevent the hydroponics from becoming too saline.