Bara Clay

Bara Clay



Bara Clay is a high performance clay with excellent natural properties. It has been used by substrate manufacturers and growers for
years all over the world. Bara Clay is chosen for its strength during extreme conditions. Our plateau clay has a unique mixture of
minerals. Since the clay originates from meltwater lakes from the ice-age, it has never been exposed to chlorides. This rare mineralogical
composition makes it unique and powerful.

RHP certified
Bara Clay has been RHP certified since 1998. Bara Clay is heated to 80 degrees C. It is safe, dry and easy to handle, easy to distribute in the peat. The clay content (particles <2μm) of of Bara Clay granulate is very high. The Bara Clay in the granulate has a unique composition and a high level of 3-layer clay minerals such as Illite and Smectite, that gives a high buffering capacity. Because of the heating, the clay is very dry when delivered. This fact together with the high content of clay minerals simply give you value for the money.

During the last ice age there has been a unique creation of a wonderful clay in the southern parts of Sweden. This clay is remarkable since it is formed on hills and not in valleys like most other clays. Hence the name – Plateau Clay.

Due to its high extraction place the clay has never been in contact with groundwater. Throughout the millenia of rain, lime, chloride and sodium sulphides have been washed out and only remaining the stable (favorable) minerals. The Bara Clay is clean with extremely low levels of heavy metals and therefore very suitable for professional horticulture. Bara Clay naturally contains the correct mineral composition with recordable trace and micro elements, which plants (roots) favour. Bara Clay is 100 % natural with no added minerals.


(Water Uptake Characteristic)

A substrate with high Water Uptake Capacity is important for the grower. A substrate should absorb water quickly and evenly, in order to optimize the irrigation time. A substrate with a strongly hydrophobic peat surface often have problems with long irrigation times and uneven distribution of moisture in the substrate.

The high content of Illit and Smectite minerals in Bara Clay cover the peat surface and make the substrate strongly hydrophilous. This meaning that substrates mixed with Bara Clay absorbs water quickly and evenly. A substrate with Bara Clay makes a big difference in the Water Uptake Characteristic (WOK), see the diagram.

(Cation Exchange Capacity)

A high Cation Exchange Capacity in the substrate benefits the grower by keeping nutrients in the substrate for a longer period of time and nutrients do not wash out. In outdoor production, as much as one third of the nutrients can be washed out of the pots. Having a substrate with high Cation Exchange Capabilities makes the substrate highly flexible on distributing the nutrients.

Three layer clay with Clay minerals of Smectite and Illite as in Bara Clay have high Cation Exchange Capacity in substrates, see the diagram.

(Anion Exchange Capacity)

A substrate with high Anion Exchange Capacity in the substrate is as important as a high CEC. A substrate with high AEC has a high P-buffering capacity that makes a difference in the uptake of Phosphorus. Growers have found that this supports and increases the plants root system and plant tissue. The easily mobile Phosphorus is often washed out from the substrate, which is detrimental for both the plants and the environment.

The unique Bara Clay has the right mineral composition for a high buffering. With Bara Clay in the substrate the P-buffering capacity can have up to an 60-70 % increase, see the diagram.


Using Bara Clay in the potting soil is an effective method to buffer fertilizers. By adding Bara Clay to substrate it is possible to avoid leaking of fertilizers, and also gaining flexibility in the fertilizer management.The percentage indicates the buffering of major elements in solution with Bara Clay.

  • In addition to the buffering of cations (+), there is a clear buffering of anions (-).
  • Because of the buffering the EC will be flattened 30-40 %.
  • At higher doses of fertilizer or the accidental release of (coated) fertilizers it will prevent too high EC in the root environment.
  • The buffered ions on the clay complex remains avaliable for the plant and do not rinse out.


It is known that a high CEC is important. What the CEC value doesn’t tell is what ions and to what proportions the various Cat-ions and An-ions are fixated into the clay complex. The CEC of Bara Clay is mainly formed by Ca2+, Mg2+, K+ in the right proportion. Professional growers know that ions such as K+, Ca2+, Mg2+, NH4+, NO3, SO42- and PO43- are necessary for the plants. It is of importance that specifically these ions are the ones that are taken up by the clay in the substrate and given back to the plant root when it calls for it. It is therefore important to be sure that the clay mineral is mainly occupied by the Ca2+, Mg2+, K+ in the right proportions and not by others, for example Na+-ions.

Bara Clay contains a high content of clay minerals (particles lutum <2μm), combined with a high and good balance between Cat- and An-ions. This is the important value for a high quality useful horticulture clay.

Results of pH measuring during growing period

The test was done in a nursery crop and potting outside at the end of April. A slow release fertilizer, mixed into the substrate, was used. the pH was measured directly after potting, after 8 weeks, 16 weeks and after 8 months (after wintering).

To compare the same substrate three strategies was used:

  • Substrate without clay.
  • Substrate with 40 kg/m3 standard Bara Clay.
  • Substrate with 40 kg/m3 Bara pH stable clay.

The results showed that Bara pH stable Clay is able to stabilize the pH when pH is dropping during the
growth period.


In recent years we have seen more problems with the pH during cultivation. The pH doesn’t remain stable enough. One reason is the use of potting soil with ”lighter” peat and other materials like coir and bark. This reduces the possible amount of lime that can be mixed in to the substrate while “lighter” peat and also coir and bark naturally have a higher pH at start. Less liming means
a smaller buffer against acidification.

Bara Clay has a natural pH buffering capacity that stabilizes the pH level over the growing period. In situations with problems to keep a stable pH, we recommend Bara pH stabilization Clay in the substrate, in order to create a larger buffer and stable pH during cultivation.


Bara Clay is used to bind the peat together in substrates to form stable plugs or press pots. This enables the substrate manufacturer to use younger peat. The clay that is used for this purpose is often a mix of fractions, which we recommend based on our tests.


For most plants Silicon is a sensitive nutrient. Some cultures are more sensitive than others. If Silicon is available in the substrate, roots can absorb as much Silicon as needed. Silicon ensures the plant to become both strong and healthy.

Field trials has shown that plants absorb larger quantities of Silicon in the tissue when grown in substrate with Bara Clay. Bara Clay is a natural and clean clay which is rich in Silicon.



For precise dosage recommendations, type of culture, pot size, peat fraction, irrigation and fertilizer management has to be considered.

Product info


Density: 880 kg/m3
Moisture: 2-5 %
Content: Clay powder (<200 um)
Big Bag (1000 kg)


Density: 1150 kg/m3
Moisture: 2-5 %
Content: Clay granulate (0-1 mm)
Big Bag (1000 kg), Loose material


Density: 1150 kg/m3
Moisture: 2-5 %
Content: Clay granulate (0-2,8 mm)
Big Bag (1000 kg), Loose material


Density: 1150 kg/m3
Moisture: 2-5 %
Content: Clay granulate (2-6 mm)
Big Bag (1000 kg), Loose material


Density: 1150 kg/m3
Moisture: 2-5 %
Content: Clay granulate (1-6 mm)
Big Bag (1000 kg)

Mer info