Where the ParGro Quick Drain Block Earns Its Keep on a Flood Table
The Biggie is the tall one in the Pargro range. It is a 6 x 6 x 6 in cube of basalt stone wool with a hole sized for a 1.5 in starter plug. Grodan wraps it in black-and-white foil and runs the fibres vertically, so water moves down and out rather than pooling in the base. Capillary rise on most flood tables stops around 4 in, which is the entire reason a six inch block exists. The top of the cube stays genuinely dry between shots, and roots chase the water down instead of sprawling sideways. The wool itself is inert, so the EC you mix is the EC the roots actually see. The trade is weight and cost per plant. On a short veg those upper inches never really get used, and the Jumbo is the better call.
Fitting a 6 Inch Rockwool Block Into the Rest of the Pargro Range
The Pargro line is built so one substrate carries a crop from plug through to finish. A 6 inch rockwool block sits at the end of that line for growers working on tables. Cuttings root in a plug, move into the block when white roots show at the sides, then finish there or land on a slab. The foil wrap is opaque and sealed along the sides, so algae stays off the shoulders and light never reaches the wool. Case quantities suit a full bench turn, while the single is there for trialling the format before committing a whole room. Pargro is the value line rather than the flagship, so the fibre spec is basic next to the Grodan Delta wool.
Key Features
- Six inch height: Puts the top of the cube above the capillary reach of a standard flood table.
- Pre-drilled hole: Takes a 1.5 in starter plug without cutting or forcing the wool.
- Vertical fibre structure: Moves water down through the block so drainage happens fast and evenly.
- Foil wrap on four sides: Keeps light off the wool, which holds algae and moss off the shoulders.
- Inert basalt stone wool: Adds nothing to the feed and holds nothing back, so EC stays where you set it.
- Case of 64 or single: Room-scale quantity for a full turn, or one block to test the height first.
Technical Specifications
| Specification | Value |
|---|---|
| Brand | Grodan |
| Product Line | Pargro Quick Drain |
| Part Number | 328458 / 328458-S |
| Format | Biggie block with hole |
| Dimensions | 6 x 6 x 6 in |
| Hole | Pre-drilled, sized for a 1.5 in starter plug |
| Material | Basalt stone wool, inert |
| Wrap | Black and white foil, sides sealed |
| Fibre Orientation | Vertical |
| Case Count | 64 blocks |
| Single Format | 1 block |
| Drainage | Balanced drain with moderate water holding capacity |
| Suitable Systems | Flood and drain tables, drip lines, hand watering |
| Nutrient Contribution | None, the substrate is inert |