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As early as the 17th century, researchers found that plants need a handful of nutrients to survive and don't need to grow in soil. To date, the minimalist culture of indoor plants in special balls has proven successful. A special fertilizer is of great importance, because the chemical properties of the soil differ greatly from the natural state in the earth. In contrast to cultivation in soil, hydroponics has numerous positive effects.

Hydroponics for indoor plants

The term hydroponics means something like water cultivation. With this type of cultivation, the plants do not grow in conventional potting soil, but in a special substrate that stores water. Expanded clay is the most common variant in which a wide variety of plants are grown. The balls provide a stable base for the roots to hold on to. Vital nutrients are supplied to the plants via the irrigation water.


Hydroponic houseplants require less repotting, while making repotting easier and cleaner. The roots are better supplied with air and can be more easily checked for possible damage. Many plants grow better in the special substrate, increasing their longevity. In addition, no pests that prefer to settle in the soil of indoor plants can settle here. House dust allergy sufferers benefit from better room air because the substrate does not provide a breeding ground for allergens. There are also advantages in terms of care:

  • Casting units are reduced
  • calcareous water is neutralized by ion exchangers
  • Fertilization required less often
  • all plants get the same fertilizer
  • no risk of over-fertilization
  • Substrate can be reused after boiling

Suitable plants

Almost all plants are suitable for hydroponics. Since this form of cultivation is geared towards longevity, green plants are more suitable than short-lived flowering plants. In hospitals, banks or office buildings, palms, ferns and foliage plants are preferably grown hydroponically because of the numerous advantages. If you are interested in this form of cultivation, you should take cuttings from the desired plants and grow them in expanded clay. These types are particularly suitable:

  • birch fig
  • dragon tree
  • elephant foot
  • Aralia

Many indoor plants are offered commercially for this form of cultivation, because they are bred in the appropriate environment. If your ornamental plants are still young and have developed a strong root system, you can also get them used to wet culture. Switching from soil to expanded clay is problematic for older indoor plants. These have already developed a highly branched root system, which is difficult to free from soil. Root damage cannot be ruled out and offers entry points for pathogens.

tip: Cacti and orchids are ideal for cultivation in expanded clay. However, they need sufficiently long drying periods after the water level indicator has dropped to its minimum.

The right vessel

There are special planters that are equipped with a water level indicator. This way you know exactly when to water your plants again. A pot with a special fertilizer shaft, into which a long-term fertilizer is filled, is practical. Plants only get the nutrients they need to grow. You will find a wide range on the market, so you can choose the pots according to your taste. Planters for hydroponics are made of ceramic, metal, plastic, wood or glass. You don't necessarily have to buy pre-made hydroponic pots if you already have the necessary supplies:

  • sufficiently large cachepot
  • special plant liner that does not have to reach the bottom of the pot
  • Plug-in water level indicator for the plant insert
  • suitable substrate such as expanded clay

notice: Make sure that the plant liner is absolutely waterproof. Then you can also put them in clay pots or untreated wooden vessels.

Suitable substrates

In hydroponics, the plants are placed in an inorganic substrate that is free of lime. Different materials can be used. They differ in grain size and have different levels of water storage capacity. You can use broken bricks or coconut fiber as well as vermiculite or diahydro. If you use a non-swellable substrate, the water supply must be provided by an external pump system. The fabrics have different advantages:

  • Perlite: volcanic rock that retains moisture and binds nutrients
  • Basalt: volcanic rock that provides a stable footing
  • Expanded clay: baked clay balls with light weight and high swelling capacity
  • Rockwool: artificially produced substrate made of mineral fibers that is not susceptible to pathogens
  • Sand: suitable for plants with low water requirements due to its low water storage capacity
  • Gravel: cheap and aesthetic, but heavy and unable to store water

Instructions for repotting

Before the plant can be transplanted into the appropriate substrate, the root system must be completely free of old soil residue. Even the smallest particles offer fungal spores an optimal breeding ground. Shower the root ball with lukewarm water until completely clean. If you have already used the hydroponic substrate, you should clean it and sterilize it in the oven. Cover the bottom of the plant liner with balls of expanded clay, styrofoam or perlite and insert the plant. When filling up afterwards, great caution is required so that the roots are not damaged. Gently tap the jar on a surface so that the beads are evenly distributed and compacted. A refill may be necessary. The plant must then be prepared for hydroponics:

  • Pour lukewarm water until the water level indicator levels off in the middle
  • Avoid relocation in the coming months
  • once plants have established new roots, they can be tended like all hydroponic plants


Irrigation is similar for all hydroponics. Water until the water level indicator is at its optimum. It doesn't matter if you don't water to the maximum level. If the indicator does not react immediately, a light tap will help. This loosens any accumulated powder. The plants consume the water at different intervals until the level drops to its minimum. To prevent root rot, you should take a three to six day break from watering and only then top up the water again. These care measures also ensure optimal growth:

  • Clean substrate once a year
  • if there is a putrid smell, completely replace and clean the substrate
  • Use special fertilizer
  • Cut off brown leaves and shoots and remove from the substrate

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