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Grodan Gro-Block GR32 Improved Hugo Rockwool Block, 6 x 6 x 6 in (each)

In stock

Quantity discounts available. Please call (707) 588-8844.

Introducing Grodan Gro-Blocks Improved, a product specifically engineered to deliver real results for your crops, developed by plant scientists, researchers, and top growers.

Grodan Gro-Block GR32 Improved Hugo Rockwool Block, 6 x 6 x 6 in (each)

Quantity discounts available. Please call (707) 588-8844.

Also available in a case of 64.

New and improved stone wool substrate with advanced wetting technology from Grodan

Introducing Grodan Gro-Blocks Improved, a product specifically engineered to deliver real results for your crops, developed by plant scientists, researchers, and top growers. The uniform distribution of water and nutrients throughout the block allows for more efficient use of the entire substrate volume. Full saturation of the blocks with no dry spots and improved EC control with less water is achieved in the rootzone due to the uniform, optimized wool resulting in a sustainable water and nutrient use. Improved “re-wettability” able to more easily increase water concentration in the substrate.

Grodan partnered with the Wageningen University and Research Facility and top growers from all over North America to determine the optimal stone wool substrate and irrigation strategies for indoor and greenhouse specialty crops. The result of this scientific rigor is Grodan Gro-Blocks Improved with our Advanced Wetting Agent. These leading edge blocks have the optimal fiber structure and physical properties for crop uniformity, more even Water Content (WC) and Electrical Conductivity (EC) distribution throughout the entire block, and the greatest steering capabilities available.

Water distribution is more uniform throughout the entire block which is the basis for a well-defined root system with higher capacities for water and nutrient uptake to produce robust and vigorous crops. These benefits translate to higher yields, improved quality, less water and nutrient usage, and reduced sensitivity of the crop to diseases.

Key Features

New and improved wetting agent and hydrophilic technology greatly enhances the water characteristics of Grodan Gro-Blocks Improved giving even better water distribution over the height of the block. This results in greater plant development and steerability and more efficient use of water and nutrients.

Optimized wool structure allows for faster rooting-in and nutrient solution replenishment, all while the Gro-Block Improved maintains its structure, firmness, and rigidity throughout the growing process.

Key Benefits

Excellent Control

The improved initial saturation and improved water distribution throughout the height of the blocks results in improved root growth, enhanced water holding capabilities and more stable EC behavior in the root zone. This makes it is easier than ever before to control your crop, with even less inputs, from propagation through to harvest.

Greater Steering Possibilities

Advanced technology used in Grodan Gro-Blocks Improved combined with the uniformity of WC and EC throughout the entire block provide better vegetative and generative steering. WC and EC can be adjusted more rapidly and efficiently. This offers additional assurances, such as in the case that the grower would need to adjust root zone WC or EC.

Roots Making Better Use of Entire Substrate Volume

Both the rooting-in and rooting-through plant processes have improved. Trials have repeatedly shown that the initial rooting-in phase in Grodan Gro-Block Improved occurs several days faster, speeding up the vegetative phase and time to harvest. The more effective rooting-through of the entire substrate volume leads to a visible increase of roots and thus, better water and nutrient uptake. Naturally, this results in enhanced plant health and productivity from start to finish.

Stronger, More Vigorous Plant Development

Due to the better developed root system in Grodan Gro-Blocks Improved, the trial results showed improved plant growth, including larger plant size, greater stem thickness and bigger leaves. Ultimately, this can lead to higher yield, while at the same time the stronger, more vigorous plants show increased resistance to disease.



Saturate Grodan Gro-Blocks in a nutrient solution of roughly 1.5 EC and 5.5 pH with a course spray or submerged in the solution for up to 2 minutes. Do not over saturate the blocks or leave soaking for extended periods of time.

Measure Wet Weight

Measure the weight of the block at saturation. Compare this weight to the weight of the blocks throughout the growing cycle. When the WC of the block is 55% to 65% apply the first irrigation.


Insert the well rooted Grodan Starter Plug into the hole of the saturated Gro-Block.


  • The volume of the irrigation event should be equal to 3% to 6% volume of the stone wool that you are watering. For example a Delta10 (4”x4”x4”) has a total volume of 1 liter, 3% would be 30mL. When stacking blocks on slabs or other blocks add the volumes together to determine the proper irrigation volume.
  • Using a measuring cup record the amount of time it takes the dripper(s) to achieve the 3% to 6% watering volume. That time is your PUMP ON time.
  • The use of pressure compensated drip emitters (0.5 gph to 1 gph) can help ensure that all your plants receive the same volume of irrigation.
  • Regular measuring of flow rates from multiple emitters will help ensure consistent watering across your farm.
  • When using pressure compensated drippers, you need to ensure that your pump can meet the minimum flow rate and pressure requirements. Contact manufacturers before purchasing pumps.
  • Filters, lines, and drippers should be flushed and cleaned properly between crops.
More Information
Manufacturer Part NumberGR32
Distributor Part NumberHGC713087, 713087, RW274999