12qt Shoebox Refill Kit | Mushroom Substrate and Grain

12qt Shoebox Refill Kit – Clean, Simple, and Ready to Run 2 lb Sterile Grain + 5 lb Substrate — Built for 12qt Shoebox Tubs Fast Refill. Zero Guesswork. The 12qt Shoebox Refill Kit gives you everything needed to reload your shoebox grow without starting from scratch. Designed for clean handling, reliable colonization, and simple workflow. What’s Included 2 lb Sterile Grain Bag – Choose Corn or Milo (4T Unicorn bag with filter) 5 lb Premium Substrate – Hydrated to field capacity FREE Self-Healing Injection Port Why Growers Choose This Kit Lab-Sterilized Grain – Sterilized 2.5 hours in SH Scientific autoclaves at 15–17 PSI Balanced Ratio – Sized specifically for 12qt shoebox tubs Premium Substrate – Clean, consistent hydration and structure Streamlined Workflow – Ideal for quick turnaround grows How It Works Inoculate the sterile grain bag. Allow full colonization at 70–75°F. Mix colonized g