Custom substrates

We mainly use natural raw materials, such as coco and peat for our potting soil mixtures. Both are of natural origin; organic and recyclable. This gives them their environmentally friendly nature. Other raw materials such as perlite, clay, sand and bark can be added to a potting soil mixture.

We work with RHP-certified raw materials. RHP certification guarantees that the substrate meets the right quality requirements for aspects such as water and air content, pH and EC.

Coco peat

Coco peat is made from the husk of the coconut. It is a renewable resource because palm trees continuously produce new coconuts. For the finer substrates, such as Knaap Elite, we use coir, which is a by-product from the fibre-industry. The coarse substrates, such as Knaap Profit and Knaap Maximum, are made by cutting up the husk. Coco peat is naturally airy, absorbs water easily and has good drainage capacity.

Coco peat is a natural product. By transporting the coco peat products in compressed form, we limit the environmental impact of transport. Coco materials can be recycled and reused as a soil improver.


Peat can be roughly divided into two types: white and black peat.
White peat can be cut or milled to produce peat fractions. Black peat is used as garden peat in substrate mixtures. This product comes from the deeper, more decomposed peat layers. Low temperatures during the winter cause the peat to form the pores needed to absorb water and air.

Peat is known for its low EC and pH values. The physical properties are determined by the type of peat and the fraction used. Coarse peat fractions give the potting soil mixture an airy structure, whereas the mixture will retain more water with a higher ratio of garden peat or milled peat.

The Van der Knaap Group has acquired the concessions for a number of peat bogs in Estonia. This enables us to guarantee the availability and quality of our peat materials even better.


Not all potting soil mixtures are suitable for all crops. That is why we consider our customers' wishes and the growing requirements of the crop when composing a potting soil mixture. We do this in consultation with the grower and by using our expertise as a potting soil manufacturer. This process always involves custom solutions.

When composing a mixture we consider aspects including crop, pot size, potting method, (starter) fertiliser, dripper system and growing conditions.

We are happy to help you select the perfect product for your application.
More informationKoen de Koning
+31 (0)174 212224
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