Grodan IMPROVED Gro-Blocks 4″X4″X2.5″

Grodan Stonewool (Rockwool) Growing Blocks

What is Grodan?

Grodan Stonewool is a premium hydroponic growing medium made by melting natural rock and spinning it into fine fibers, similar to cotton candy, before forming it into cubes, blocks, and slabs. Unlike many rockwool products, Grodan designs different fiber structures for different plant growth stages, helping maintain the ideal balance of moisture and oxygen around the roots.

Why Growers Love Grodan

  • Excellent water-holding capacity.
  • Maintains high oxygen levels around roots.
  • Encourages rapid root development.
  • Clean, sterile growing medium.
  • Consistent results from crop to crop.
  • Ideal for hydroponic and drip irrigation systems.
  • Easy transplanting from cube to block to slab.
  • Suitable for vegetables, herbs, ornamentals, tropicals, and cannabis.

What Do You Do With It?

Starting Seeds

  • Soak cubes in properly pH-adjusted water.
  • Place seeds in the pre-made hole.
  • Keep warm and moist.
  • Roots develop quickly thanks to the ideal air-to-water ratio.

Rooting Cuttings & Clones

  • Insert fresh cuttings into Grodan cubes.
  • Place under humidity domes or clone lighting.
  • Maintain humidity and proper temperatures.
  • Watch for rapid root development.

Growing Larger Plants

  • Place small cubes into larger Grodan blocks.
  • Blocks can sit directly on Grodan slabs for expanded root volume.
  • Feed using hydroponic nutrients through drip irrigation or hand watering.

Grodan Delta Blocks

Grodan Delta Blocks feature:

  • Uniform structure for consistent growth.
  • Grooved bottoms for improved drainage.
  • Various sizes for different crops.
  • Compatibility with AO plugs and starter cubes.
  • Suitable for direct seeding and transplanting.

Grodan Hugo Blocks

The largest Grodan growing block available.

Benefits:

  • Supports larger plants.
  • Provides substantial root volume.
  • Often eliminates the need for a slab underneath.
  • Popular for high-value crops and large fruiting plants.

Great For

  • Cannabis
  • Tomatoes
  • Peppers
  • Cucumbers
  • Lettuce
  • Herbs
  • Houseplants
  • Tropical plants
  • Cloning
  • Seed starting
  • Commercial greenhouse production

Description

Grodan Stonewool (rockwool) is made from molten rock spun into cotton candy-like fibers and then compressed into cubes, blocks, or slabs. Where other rockwool brand manufacturers cut all sizes from one batch of wool, Grodan is unique by making different types of fibers. The purpose is to support the requirement of the plant in the different plant stages. Grodan has a tremendous capacity for absorbing nutrient solution while retaining plenty of oxygen for rapid plant growth. Grodan comes in graduated sizes. Seedlings started in cubes are easily transferred to blocks and then onto slabs, if desired. Seedlings or cuttings started in the Grodan cubes can also be transplanted into more traditional planters and growing mediums. Grodan Blocks -Grodan Delta blocks are the most uniform blocks available on the market. They feature improved grooves at the base to promote better drainage. They are available in a large assortment of sizes and configurations to suit all types of plants. These growing blocks are used for direct sowing or “blocking on” of Macro and Multiblock raised plants. AO 36/40 plugs fit well into the hole sizes provided by the blocks. The blocks can then be placed on top of a slab to provide for a larger growing volume. Hugo is the largest of the growing blocks. It provides enough growing volume to support a larger plant, so it does not need to be placed on top of a slab.

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