Rockwool

Stone wool, or mineral wool, has become a primary medium for propagating seeds and mothering seedlings in hydroponic gardens. Made from natural stone and chalk, it was used originally in building construction as insulation against sound and heat because of its porous structure. That form lets mineral wool do two things, reducing stress for gardeners, especially beginners:

• It keeps water and nutrient levels just right.
• It helps to promote strong young roots by allowing oxygen to reach them.

Mineral wool is manufactured in forms convenient for gardening, and it's easily cut into any shape or size needed.

Hydroponics gardening began years ago with stone-based, highly porous Rockwool as a medium for growing when soil was unsuitable. It’s so effective that it’s still widely used in greenhouses worldwide to grow vegetables hydroponically. Here’s why it works: Rockwool can hold 80% of its volume in water or nutrient solution, with oxygenated air filling the other 20% of its cavities, making roots strong. Although its pores hold water, the stands themselves do not soak it up. Buy Rockwool plugs, blocks or cubes, or buy slabs that are cut easily with shears, a saw or even a bread knife. Rockwool is best suited for hydroponic systems like flood and drain and top feed, drip systems.

ParGro Quick Drain (QD) is stone wool made by Grodan to drain better than original Grodan Rockwool. Choose from slabs and plugs in a range of sizes for use in ebb and flow systems.