Description
Consistent Rooting from a Cube That Holds Its Shape
Grodan rockwool blocks are a high-performance, reliable grow media made to deliver strong growth through the propagation phase. Available with a 2.5cm small hole or a 3.6cm large hole, they suit fine seed and small cuttings through to thicker stems. The cube is solid and holds its shape, so it does not slump when saturated. They offer excellent saturation and re-saturation, a positive effect on EC refreshment and distribution, and an excellent air-to-water ratio for rich root growth.
Key Benefits
- Two hole sizes - 2.5cm for seed and fine cuttings, 3.6cm for thicker stems.
- Excellent air-to-water ratio - roots get oxygen as well as moisture.
- Saturation and re-saturation - takes water back up evenly rather than channelling.
- Better EC distribution - fewer hot spots and less salt build-up in the cube.
- Holds its shape - solid, durable and resistant through handling and transplant.
- Strictest quality standards - batch consistency you can plan around.
Slow, Patchy Rooting and Transplant Shock
Cuttings that root at different rates wreck a schedule, and the culprit is usually a substrate that holds too much water or dries unevenly. Waterlogged cubes starve roots of oxygen, giving weak roots and slow growth; dry pockets cause poor nutrient uptake and stalled strike rates. A balanced air-to-water ratio and even re-saturation mean roots develop into a firm plug, so transplant shock is minimal.
How to Use
- Pre-soak: soak the blocks in water adjusted to around pH 5.5 before use.
- Drain: let excess water drain off - never squeeze the blocks, as that ruins the structure.
- Insert: set a seed, or a fresh cutting dipped in rooting gel, into the hole and firm gently.
- Environment: keep the tray in a propagator at around 21-25C, opening the vents gradually.
- Watering: keep the block moist but never saturated - overwatering is the top cause of failed cuttings.
- Transplant: move on once roots show at the sides or base, into a larger block, slab or pot.
Technical Specifications
- Type: stone wool (rockwool) propagation block
- Range: Grodan Delta
- Block size: 7.5 x 7.5 x 6.5 cm
- Stage: propagation - seeds and cuttings
- Structure: solid, holds its shape when saturated
- Water handling: even saturation and re-saturation
- EC: even EC refreshment and distribution
- Air-to-water ratio: balanced for rich root growth
- Soak pH: about 5.5
| By size | 2.5cm (Small Hole) / Single | 2.5cm (Small Hole) / Strip of 8 | 2.5cm (Small Hole) / Box of 384 |
|---|---|---|---|
| Hole | small | ||
| Supplied as | 1 block | strip of 8 | box of 384 |
| By size | 3.6cm (Large Hole) / Single | 3.6cm (Large Hole) / Strip of 8 | 3.6cm (Large Hole) / Box of 384 |
|---|---|---|---|
| Hole | large | ||
| Supplied as | 1 block | strip of 8 | box of 384 |
Questions & answers
Which hole size should I choose?
The 2.5cm small hole suits seed and fine cuttings, and the 3.6cm large hole suits thicker stems.
Do I need to soak them first?
Yes. Pre-soak them in water adjusted to around pH 5.5, then let the excess drain off. Never squeeze them, as that ruins the structure.
How wet should I keep them?
Moist but never saturated. Overwatering is the most common cause of failed cuttings.
When do I transplant?
Once roots show at the sides or base, move them into a larger block, slab or pot.
How are they sold?
Singly, in strips of 8 or in boxes of 384, in either hole size.
