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How to Inoculate a Grain Spawn Bag (Liquid Culture or Spore Syringe)
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Objective: Introduce mycelium into a sterilised grain bag safely to start mushroom cultivation.
Materials Needed
- Sterilised grain spawn bag (with filter patch)
- Liquid culture (LC) or spore syringe
- Alcohol wipes or 70% isopropyl alcohol
- Gloves
- Face mask (optional but recommended)
- Lighter, Alcohol lamp or Induction coil (for flame/heat sterilisation, if needed),
- Syringe needle (if not pre-attached)
Step 1: Prepare Your Workspace
- Work in a clean area to reduce contamination (e.g., still air box or near a HEPA-filtered space such as a laminar flow hood).
- Wash hands thoroughly and wear gloves.
- Spray gloves & Wipe down the workspace with 70% isopropyl alcohol.
Tip: Unless using a laminar flow hood it is best practice to minimise airflow and avoid drafts, which can carry contaminants.
Step 2: Prepare the Bag
- Shake the grain bag gently to distribute grains evenly. (you do not have to do this but some prefer using this method)
- Inspect the bag for any cracks or leaks. Do not use if compromised.
- Wipe down the grain bag with 70% isopropyl alcohol.
- Wipe the injection port with the 70% isopropyl alcohol patch.
Step 3: Prepare the Syringe
- For Spore Syringe: Shake well to suspend spores evenly.
- For Liquid Culture: Shake gently to mix the mycelium without creating bubbles.
- Remove needle from packet unscrew stopper and insert needle onto syringe.
(If reusing a needle flame needle until it glows red and let cool for a few seconds).
Step 4: Inoculation
- Insert the syringe needle through the bag’s injection port.
- Inject 3 mL of Culture (5ml for Spores) (adjust depending on bag size).
- Remove the needle carefully and wipe any drips with an alcohol wipe.
Tip: Unless you are inoculating multiple bags then place the alcohol wipe over the base of the needle squeeze gently holding the wipe slowly removing the needle keeping the wipe intact to the tip of the needle, move the needle to the next bag injection port and slide the needle into the next injection port following back through from step 4.1
Step 5: Seal and Incubate
- Reseal the injection port (if necessary, with tape or self-sealing patch) Mycoforge bags have a self healing port!
- Roll the bag on to each side for 10 seconds to lightly to disperse the liquid with grains.
- Place the bag in a clean, dark, warm location appropriate for the mushroom species (typically 18°C -23°C).
Step 6: Observation and Maintenance
- Check daily for signs of colonisation (white mycelium growth).
- Remove any contaminated bags immediately.
- Fully colonised bags are ready for fruiting or expansion.
Contamination Risk Notes
Spore Syringes contain more airborne contaminants, has a slower colonisation time & gives more time for mould/contaminants to develop.
Liquid Culture Mycelium is already established, outcompeting contaminants has faster colonisation which reduces the contamination window.
Useful info: Use liquid culture for higher success rates if you want faster colonisation and lower contamination risk. Spore syringes are easier to store long-term and start new strains but carry higher contamination risks.
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