Grodan Rockwool Products

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GRODAN Delta Benefits

1. Effortless startup of propagation

GRODAN Delta is the perfect block for propagating young plants under a wide range of propagating conditions. The block is easy to saturate and water is distributed uniformly throughout the block, so reliable and vigorous plant growth is guaranteed.

2. Uniform WC and EC distribution

Based on the Delta Technology, the structure of the block and water distribution throughout the substrate have been improved. Newly transplanted plants will benefit thanks to the ready availability of water and the balanced nutrient solution (EC), encouraging the roots to penetrate deeply into the blocks.

3. Easy WC management

The water content levels can be easily managed between 55% and 80%. This applies equally to low and high water content levels. If the moisture content level threatens to drop too low, it can be simply be restored to the desired level, for instance 80%. Thanks to the variations in the small and large pores, the roots are always guaranteed a sufficient supply of air and water.

4. Excellent root growth throughout the block

The Delta Technology ensures uniform distribution of water and nutrients throughout the block. Newly transplanted plants will benefit thanks to the ready availability of water and EC, encouraging the roots to penetrate deeply into the slabs

5. Greater firmness for better handling

As mechanisation has been increasingly introduced into the propagation process over the years, the blocks must be able to withstand handling better during propagation. The stable firmness of GRODAN Delta becomes particularly important when the blocks are placed, spaced and picked up several times during propagation. An added advantage is greater protection for the roots during transport from the propagator to the grower


Perfect for effortless propagation

GRODAN Delta forms the foundation for uniform and perfectly controllable propagation of plants – an absolute condition for vigorous and healthy plant growth. Each block has an identical density, flexibility and sturdiness, guaranteeing even distribution of the WC, EC and pH. The result is a uniform and high-quality plant.
GRODAN Delta is the best block for essential properties such as firmness and saturation. These qualities make GRODAN Delta ideally suited for propagators who want to secure the success of their processes.

Product Specifications

  • Suitable for flower and vegetable propagation
  • Control range 55 – 80%

GRODAN Delta application

GRODAN Delta is a widely used block for propagating tomatoes, sweet peppers and cucumbers worldwide. The easy water and EC distribution, handling and saturation offer propagators a reliable start to production.


GRODAN plugs are known for their homogeneity and reliability. They are the ideal basis for automated processing, uniform germination and a high success rate with pricking out. The shape and firmness of the plugs are of a quality that makes processing significantly easier, whether that processing is mechanical or manual. Every plug has a uniform density, firmness and fibrous structure. This means that distribution of water, nutrients and pH-value is also uniform, which has a beneficial effect on germination results.

The fibrous structure, predominantly vertical, gives the plugs the desired resilience. One practical advantage when pricking out is that the plug retains its shape, makes good contact with the block and guarantees fast root growth. A good balance between small and large pores in the stone wool ensures an ideal air to water ratio in the plugs. The fibrous structure creates a balanced distribution of feedwater throughout the entire plug. In short, the homogeneity, flexibility, shape and firmness of GRODAN plugs create the foundation for the optimum germination process and a uniform sowing result.