Expanded clay or clay granules offer some tangible advantages, especially for indoor plants. To ensure that your plants benefit from these, you will find all the important tips for using the fired clay pellets here - plus tips for buying high-quality material.

Clay granules are an interesting assistant in caring for indoor plants

Table of Contents

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  1. the essentials in brief
  2. What are clay granules?
  3. What can clay granules be used for?
  4. Where can you buy clay granules?
  5. frequently asked Questions

    6. the essentials in brief

    • Clay granules consist of fired clay pellets (€22.65) and can be used very well as a substitute for potting soil.
    • Alternatively, you can also mix the material with potting soil to improve the water storage capacity of the substrate.
    • Clay granules have a very high water storage capacity, which is why you need to water indoor plants cultivated in them less often.
    • However, there are a few things to keep in mind when caring for these plants. Since clay granules do not contain any nutrients, you need to regularly feed these plants with a special fertilizer.

    What are clay granules?

    Clay granules are literally clay granules

    As the name suggests, clay granules are made from clay. This is a particularly fine-grained type of soil that is created by the decomposition of rock spades (again a collective term for various types of rock). Clay is considered a good water reservoir, a property that is further improved and optimized through the clay granulate manufacturing process. To do this, clay is ground, granulated and then fired at extremely high temperatures of around 1200 degrees Celsius.

    During this process, the organic substances contained in the starting material burn, producing carbon dioxide. The gas in turn inflates the granules so that the typical round balls are formed. Clay granules have a porous surface and are therefore able to absorb and store water. For this reason, the material is ideal as the sole or additional substrate for indoor plants, but also for other purposes. In the following sections you will find out what you can use clay granules for and what you should pay attention to.

    Types of clay granules

    There are several types of clay granules, which differ in these properties:

    • grit
    • pH and salinity
    • Suitability for plant species

    Clay granules are available in different grain sizes, i. H. the beads vary in size depending on the product. A grain size of 4/8 is suitable for most indoor plants, as the plant roots find the best grip here - the small balls with diameters between four and eight millimeters fill in gaps well and leave only a few cavities. However, they only let a little air through, which is why you prefer to use a coarser grain size such as 8/16, especially for larger indoor plants.

    There are also differences between the pH value and the salt content of the different products. Most clay granules have a pH of around 7, making them suitable for most plants. On the other hand, if you need a slightly acidic substrate for your plants, Seramis is a good choice. With regard to the salt content, there are differences between the individual products of between two and 920 milligrams per 100 grams of clay granules. If you plan to hydroponically grow your houseplants or cultivate salt-sensitive species, choose a product with less than 250 milligrams of salt per 100 grams of clay granules.

    advantages and disadvantages

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    The most important positive property of clay granulate is its ability to store water and gradually release it back to the plants as needed. Plants cultivated in this material therefore need to be watered much less frequently. This table clearly shows you the advantages and disadvantages of clay granules compared to conventional potting soil.

    benefits disadvantage
    durable, can be used again and again expensive
    good water storage contains no nutrients
    ensures an even water supply regular fertilization essential
    air permeable Moisture content cannot be seen or felt from the outside
    prevents root rot Water level indicator is therefore indispensable
    no fungus gnats and other pests that lay their eggs in soil light weight, fluctuates due to water absorption and release
    clean and suitable for allergy sufferers Larger plants in particular are in danger of tipping over without being weighed down
    does not mold

    digression

    Which is why a water level indicator is indispensable when using clay granulate

    A water level indicator is a kind of thermometer for the flower pot. However, this does not show you the temperature, but the water content of the substrate. Since, unlike potting soil, you can neither see nor feel the water content of clay granules, such a device is indispensable. A glance at the display is sufficient here: if it is at "minimum", it must be watered.

    What can clay granules be used for?

    Clay granules are probably used most frequently in the care of indoor plants, which is why we will present three areas of application in more detail here. But there are also various possible uses in aquariums, terrariums, for green roofs or when constructing ponds.

    hydroponics

    With hydroponics, you only plant and care for your houseplants in clay granules. However, it is not enough to simply replace the potting soil with expanded clay (€19.73). On the one hand, switching to hydroponics requires careful washing out of the root system so that no soil remains, on the other hand, you need special planting systems. These usually consist of an inner and an outer pot. Place the plant in the substrate in the inner pot, while the outer pot contains the water, which must be regularly topped up with the nutrient solution.

    Conversion to hydroponics - Here's how

    The conversion to hydroponics works as follows:

    1. Repot the plant.
    2. Remove the soil. Rinse residues from the root ball completely.
    3. Shorten roots that are too long, even brown (rotten) roots will be cut off.
    4. Pour a layer of expanded clay into the inner pot.
    5. Place the plant on top and fill up the inner pot.
    6. Tap the table lightly with the bottom to fill any gaps.
    7. Place the inner pot in the planter.
    8. Fill with lukewarm water and don't forget the water level indicator.

    Soil balls in clay granules - simplified hydroponics

    Leaving the root ball of the plants intact (and covered in soil) is less of a hassle. Instead, simply place the plant to be repotted with the soiled root ball in a surrounding layer of clay granules. Here the roots are practically embedded in the new additional substrate, but are still in the ground. The water level indicator should not be missing here either.

    Drainage for indoor plants - mix clay granules with soil

    Mixing soil with clay granules saves watering

    Alternatively, mix the clay granules with the potting soil to improve its water-storing properties or to guarantee an optimal supply of moisture. You have various options:

    • For pot drainage, fill a layer of expanded clay on the bottom of the pot.
    • Depending on the size of the pot, this should be between two and ten centimeters thick.
    • Place a shard of pottery over the drain hole beforehand to prevent it from clogging.
    • Mix the potting soil with fine expanded clay beads.
    • For a pot with a diameter of 15 to 20 centimeters you need about a handful.

    A water level indicator is not absolutely necessary in this case, but it can make it much easier for you to determine the right time to water.

    digression

    Crushed clay granules for pond plants

    Instead of lining the garden pond with foil or using a preformed plastic tub, you can also use clay to seal it. Clay blocks made of damp material or broken clay granules (swelling clay) are suitable for this. Depending on the size of the pond, the clay layer on the pond floor should be between 10 and 20 centimeters thick.

    Where can you buy clay granules?

    "Plants need a good substrate to find support and to draw nutrients and water from it."

    You can purchase clay granules either as a branded product (e.g. Floragard, Seramis or Dehner) or as a no-name product (e.g. own brands from DIY and garden centers such as Obi, discounter brands). Common pack sizes range from 2.5 to 50 liters of different contents, depending on what you intend to do. Larger quantities, such as those you need for sealing garden ponds, can be found in special shops.

    frequently asked Questions

    Is there a difference between expanded clay and clay granulate?

    The terms expanded clay and clay granules both refer to fired, reddish-colored clay pellets. So there is no difference in meaning between them, but there can be differences between the individual products and manufacturers - for example with regard to the grain size or the intended use. Incidentally, another name for clay granules is plant clay.

    Can I completely replace the potting soil with clay granules?

    Used correctly - as described in the article - clay granules can actually completely replace potting soil. But then you have to pay attention to a few special features when caring for your houseplants, such as using them alone without a water level indicator does not work or you have to fertilize regularly. With a simple finger test, it is not possible to determine whether the plants need water with clay granules. Since the material is also inorganic, it does not contain any nutrients. These must be supplied continuously.

    Are clay granules toxic?

    No, clay granules are generally not toxic. After all, it is a natural material that was only burned and thus made structurally stable. Chemical additives are not added to most products. You shouldn't eat the material anyway, it's not intended for that and wouldn't do you any good - your body can't digest it. Instead, the beads could remain in the gastrointestinal tract and lead to serious blockages there.

    tips

    Many a resourceful indoor plant gardener has had the idea of using compostable cat litter (e.g. based on bentonite) instead of clay granules. Although this has very similar properties to expanded clay in terms of its water storage capacity, it is not suitable as a plant substrate due to the often very high pH value. The reason is the high lime content of the material, whereas most indoor plants need a slightly acidic to neutral pH value for their well-being.

Category:

Indoor plants