What is the substrate material used in the GIY kits? Our GIY kits consist of hemp and mycelium. The hemp consists of hemp waste particles of 5 to 15mm inoculated with mycelium. By Eileen Morée|2021-02-24T12:01:42+00:00February 24th, 2021|Grow It Yourself kit| Share This Story, Choose Your Platform! FacebookTwitterRedditLinkedInTumblrPinterestVkEmail About the Author: Eileen Morée