Growing oyster mushrooms on straw
Chop straw into pieces, pasteurise it for 1 to 2 hours in water at 70 to 75 °C, let it drain and cool to below 24 °C and mix in 5 to 10 % spawn. After 2 to 5 weeks of colonisation in the dark, fruiting follows.
University of Florida / IFAS Extension · BS-01Field & Forest Products (VS) · BS-06La Mycosphère (BE) · BS-80Straw is cheap, but unlike with a kit you have to suppress other moulds and bacteria yourself. You do that with hot water: pasteurising, not sterilising.
University of Florida / IFAS Extension · BS-01La Mycosphère (BE) · BS-80Step 1: chopping and soaking
Chop the straw into pieces of 8–13 cm. UF/IFAS then soaks it overnight.
Field & Forest Products (VS) · BS-06University of Florida / IFAS Extension · BS-01Step 2: pasteurising
Submerge the straw in a bag or pillowcase in water at 70–75 °C and hold that for 1 to 2 hours. UF/IFAS gives about 74 °C for 1 to 2 hours, Field & Forest 71–74 °C for 40 to 50 minutes and La Mycosphère 60–80 °C as outer limits. So stay above 60 °C and below 80 °C.
University of Florida / IFAS Extension · BS-01Field & Forest Products (VS) · BS-06La Mycosphère (BE) · BS-80Working safely with hot water
Only use a gas or wood burner outdoors, because of carbon monoxide. Do not move a hot pot: lift the straw out with a net or bag and let the pot cool where it is.
Step 3: draining and inoculating
Let the straw drain and cool to below 24 °C, with about 65 % moisture: when you squeeze hard, at most a few drops come out. Fill the bucket or bag layer by layer with straw and spawn, up to 5–10 % spawn on the wet weight.
Field & Forest Products (VS) · BS-06University of Florida / IFAS Extension · BS-01Step 4: holes and colonisation
Make holes all round every 10–15 cm. Keep everything in the dark; ideal is 24–25 °C and 80–90 % humidity for 2 to 3 weeks. Field & Forest counts 3 to 5 weeks until the first pins. Do not let the temperature in the bucket rise above 32 °C.
Field & Forest Products (VS) · BS-06University of Florida / IFAS Extension · BS-01Step 5: fruiting and harvest
Move the bucket somewhere lighter: 10 to 12 hours of light per day, about 85–90 % humidity around it and fresh air. Harvest the whole cluster as soon as the cap edges start to flatten. After that, 2 to 4 smaller flushes follow.
Field & Forest Products (VS) · BS-06University of Florida / IFAS Extension · BS-01Mushroom Mania (BE) · BS-20If it goes wrong
Green, black or orange mould during colonisation: get rid of the bucket and keep more strictly to temperature and time next time. If it smells sour or the straw is slimy, let it drain better.
University of Florida / IFAS Extension · BS-01Field & Forest Products (VS) · BS-06La Mycosphère (BE) · BS-80Source
- Grow Your Own Oyster Mushrooms at Home (SS662) — University of Florida / IFAS Extension
- Growing Oyster Mushrooms on Straw — Field & Forest Products (VS)
- Grijze oesterzwam – Growkit — Mushroom Mania (BE)
- Pasteurization and Sterilization — La Mycosphère (BE)
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This is general growing information from the sources listed. Always follow the instructions of your kit or supplier. Only eat what demonstrably grows from your own culture of the bought, named species; if in doubt about colour, smell or shape, do not eat it.
This is not medical advice. If you repeatedly get a fever, a cough or shortness of breath while growing indoors, remove the culture and see your doctor.
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