Grodan Grow-Cubes, 5.29 cu ft Loose Box | Stone Wool Cubes for Pots and Hydro

Grodan Grow-Cubes, Stone Wool That Pours Like Potting Mix

These are small loose cubes of stone wool, about 0.4 in square, that pour into a container like a potting mix. As they settle, the cubes stack against each other and leave air pockets all the way through the root zone. That open, non-compacting structure drains fast and keeps a balanced ratio of air to water around the roots. This box holds 5.29 cu ft, or 150 L, loose rather than bagged, and weighs about 20 lb. That fills roughly 69 standard one-gallon nursery pots, which hold about 88 fl oz each. Stone wool is basalt rock melted and spun into fibre, so the cubes are light and much cleaner to handle than peat-based media. They run on their own or mixed with other loose media such as expanded clay pebbles, coco or soil. A brief pre-conditioning soak brings the stone wool to a neutral pH before planting. Rooted plugs and mini blocks transplant straight into the cubes, which close around them without packing down. The cubes fill any container shape.

Loose Rockwool for Hand Watering, Drip or Flood Tables

Because the cubes drain so freely, overwatering is hard to do in a container with good drainage. That makes them forgiving under hand watering, top-feed drip lines and ebb and flow tables alike. The flip side is a fast dry-back, so containers in a hot room need feeding more often than a peat mix would. Watch the top layer on small pots, where the cubes dry out first. Mixed into soil or coco, they open up a heavy blend and add drainage without adding weight. Mixed with clay pebbles, they hold moisture that the pebbles alone would let run straight through. Loose fill means no bags to cut open, and the box can be scooped from as pots are filled. Keep the open box covered between uses so the cubes stay clean. Stone wool does not decompose the way organic media do, so the structure holds through a long crop. Wear gloves and a dust mask when pouring dry cubes, since loose fibre can irritate skin.

Key Features

• 0.4 in Stone Wool Cubes: Loose cubes stack with air pockets throughout the root zone.
• 5.29 cu ft Loose Box: About 150 L of media, enough for roughly 69 one-gallon nursery pots.
• Fast Drainage: An open, non-compacting structure makes overwatering hard in a draining container.
• Mixes With Other Media: Runs alone or blended with clay pebbles, coco or soil.
• Lightweight and Clean: About 20 lb for the full box, and cleaner to handle than peat-based mixes.
• Any Watering Method: Suits hand watering, top-feed drip and ebb and flow tables.

Technical Specifications