the idea of using rocks is to support the plant roots, but not to absorb water...
Hygroton is a brand name...they work very well...I use em...cleaning is a bitch-a-roony, but do-able...{baking in oven for a little while works wonders}...
Hygroton is very smooth and lava rock is generally rough and porous...I've heard it said that the rough rock has more to grab onto...I've never had a problem with Hygroton...I also use rockwool cubes to start seeds and clones, I love it also...I dont grow in rockwool only because it holds water too long, but it does fine for clones and seeds...
ICEToker Reviewed by ICEToker on . Can you use red lava yard-rocks for grow medium ? Iā??ve heard people mention ā??lava rocksā?? as a grow medium, instead of Hydroton. Are they talking about special lava-rocks sold at a grow store, or the red lava-type rocks used for landscaping, that people use in their front yard in place of grass ? The yard kind is probably very cheap compared to Hydroton (they probably sell it by the cubic yard like soil). What I wonder is: 1) does it release minerals into the solution that would raise/lower the pH ? and 2) does the rock being red Rating: 5