Grodan Big Mama Single Block 8 x 8 x 8 in | Gro-Block Improved Stone Wool, No Hole

What the Grodan Big Mama Single Block Is

Big Mama is the largest block Grodan makes, a 20 by 20 by 20 cm cube of Gro-Block Improved stone wool, about 8 liters of it. The item number is 286660, no hole, packed loose 18 to a carton, and this is one block out of that carton. There is no pre-cut hole in the top, and that is deliberate. A solid top takes any smaller block set on it, a 4 in Gro-Block, a 6 in Hugo or a bare plug. The roots grow down out of the small block into the big one. The wool content is more than twice that of the Hugo. The root zone a Hugo offers through veg carries on at double the volume through flower. Gro-Block Improved is the current fibre recipe. Grodan formulates it with an advanced wetting agent and a revised wool structure. The aim is even water content and EC from top to bottom of the block. It saturates fully with no dry spots, re-wets better after a dry-back, and has the greatest steering range in the line. Stone wool is inert, holding water and air in its fibres and nothing else. Every nutrient the plant sees comes from the solution the grower puts in. That is the whole appeal in a recirculating or drain-to-waste room, and the whole responsibility too. A block this size is a final container. It stands on a slab, a tray or a bench and takes a dripper or a top-feed ring. The plant stays in it until the lights go off for the last time. The dry block weighs about 1.5 lb. Saturated it is several times that, which matters for a bench rated by the square foot. The UPC on the single block is 774783484998.

Saturating and Running Big Mama Rockwool Through a Full Cycle

Big mama rockwool, like any Grodan block, is only as good as its first soak. A cube this deep needs the soak to reach the middle. Grodan's guidance is a nutrient solution at about pH 5.5 and an EC near 1.5. The block is submerged or coarse-sprayed until it is saturated, up to two minutes. Soak it in the solution it will be fed, not in plain water, because inert wool has nothing of its own to give the roots. Lift the block out and let it drain by gravity rather than squeezing it. Squeezing collapses the fibre and the block never holds the same air again. Weigh one block saturated and write the number on the bench, because that weight is how dry-back gets measured from then on. Set a rooted Hugo or small block on top with its roots just showing, and let the roots find their way down. Keep the bench or the top edge of the block clear of standing water. A block sitting in a puddle stays wet at the bottom and the lower roots drown. Grodan's irrigation guidance is 3 to 6 percent of the media volume per shot. The first shot of the day comes when the block has dried back to 55 to 65 percent water content. For an 8 liter block that is a quarter to half a liter a shot, from a pressure compensated dripper. Because the block is tall, top feeding spreads the water better than a single stake pushed in at the side. Check run-off EC against the feed. A gap that widens is salt building in the wool, and the fix is a larger drain fraction on the next shot. Cover the top of the block, or keep it dry between shots, so algae does not take the surface. At the end of the cycle the block comes off the bench whole, roots and all, and the bench is clean for the next one.

Key Features

• 8 x 8 x 8 in, no hole: Solid top takes a 4 in block, a Hugo or a plug set on it.
• More than twice the wool of a Hugo: A root zone that lasts to harvest.
• Gro-Block Improved: Advanced wetting agent and revised wool structure, even WC and EC through the block.
• Inert stone wool: Holds water and air; every nutrient comes from the solution.
• A final container: Stands on a slab, tray or bench with a dripper or top feed.
• Grodan item 286660: Packed loose, 18 to a carton; this is one block.
• Soak guidance: pH about 5.5, EC near 1.5, saturated then drained by gravity.

Technical Specifications