Grodan Stone wool A-OK Starter Plugs 36/40 6/15 Starter Cubes, 1.5" x 1.5", 30 sheets of 98

Grodan Stonewool (rockwool) is made from molten rock spun into cotton candy-like fibers and then compressed into cubes, blocks, or panels. Where other rockwool manufacturers cut all sizes from one batch of wool, Grodan is unique in that they produce different types of fiber. The purpose is to meet the plant's needs in its different stages. Grodan has a tremendous capacity to absorb nutrient solution while retaining plenty of oxygen for rapid growth. Grodan comes in gradual sizes. Seedlings started in cubes are easily transferred to blocks and then to panels, if desired. Seedlings or cuttings started in Grodan cubes can also be transplanted into more traditional pots and substrates.

Grodan A-OK plugs are designed for the propagation of seeds and cuttings before "blocking on" to larger growing blocks. The V-shaped design of the plug prevents roots from tangling between the plugs in the A-OK sheet. A-OK plugs come in a sheet that fits a standard 10x20 tray.

Technical Data

• Size: 1.5 in x 1.5 in starter cubes | 30 sheets of 98 cubes per case
• Model 36/40 — fits standard 40-cell propagation trays
• Grodan rockwool formula optimized for seed germination and root initiation
• Prevents overwatering thanks to the air and water balance in each cube
• Transplants directly into Grodan growing blocks without disturbing roots

How to Use

• Soak starter plugs in pH-adjusted water (5.5–6.0) for 30 minutes before planting
• Place one seed per cube in the pre-cut hole and cover lightly
• Cover with a humidity dome and maintain 75–80°F for best germination results
• Water the tray from below to keep the cubes moist — avoid direct watering over the seeds
• Transplant the entire plug to the next size Grodan block when roots emerge from the sides