Key Components of Mushroom Grain Jar Lids
✅ Injection Port (Self-Healing Port) – A small rubber or silicone port that allows for clean, sterile injections of spore syringes or liquid culture without exposing the jar to contaminants.
✅ Gas Exchange Filter (Polyfill, Tyvek, or Synthetic Filter Disks) – Since mycelium needs oxygen, lids include a breathable filter to allow for gas exchange while preventing contaminants like mold and bacteria from entering. I like to use cloth surgical tape. Two pieces. Cover your lids with foil before you pressure cook.
✅ Tight Seal (Metal or Plastic Lids) – Lids must seal securely to maintain sterility but still allow for proper air exchange through the filter.
Items you will need to make your mushroom jar lids:
DIY or Premade Mushroom Grain Jar Lids
- DIY Modified Lids – Many growers modify standard metal mason jar lids by drilling a hole for an injection port and covering another hole with micropore tape, Tyvek, or polyfill for airflow. This is what I am doing in the video above. These lids work great and are usable over and over. You may need to reapply the silicon bead once in awhile.
- Pre-Made Filtered Lids – These ready-to-use plastic or metal lids come with built-in injection ports and high-efficiency filters to maximize sterility and ease of use. I have honestly never purchased these. They were so simple to make I didn’t bother. I could see buying them if you had hundreds to make.
Why Proper Jar Lids Matter
- Prevents Contamination – The combination of a self-healing injection port and a filter reduces the risk of bacteria or mold entering the jar.
- Allows Mycelium to Breathe – Without proper gas exchange, mycelium can stall or grow weak.
- Supports Faster Colonization – Well-ventilated jars allow for steady mycelium growth without excessive moisture buildup.
Want to buy the lids ready to go?
There are a bunch of different lid manufacturers our there. Here is one I found on Amazon.
As I said previously, I don’t buy ready made lids, but these look pretty legit!
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