Grow Oyster mushrooms at home – Cold water pasteurisation – Sterilize with Calcium Hydroxide

pinning oyster mushrooms

A procedure for cold water pasteurisation:

It is important to maintain cleanliness when working with mushrooms, including using equipment that has been disinfected with a bleach solution and wearing clean clothes. The room used for inoculation should also be kept clean, and the air should be purified with a solution of 10% bleach mixed with water (100 ml bleach + 900 ml water). By following these precautions, you can ensure that your mushroom related work is as sanitary as possible.

Calcium Hydroxide:

  1. First, use an electrical wood chipper (or similar instrument) to chip the straw bales into small pieces.
  2. In a large tub (56L), mix together 150 g of Calcium Hydroxide and 50 g of Gypsum (wear a mask and do not inhale the dust!).
  3. Fill the tub 3/4 of the way with clean rain water, stirring well to create a milky white liquid (start slowly, mix into a sludge and then add more water).
  4. Stuff as much straw as possible into the tub, making sure it is fully submerged in the milky water. Close the lid and let it stand for 16 hours.
  5. After 16 hours, turn the tub on its side to drain the water for 2-3 hours.
  6. It is important to maintain a clean and sterile environment when working with the straw. Take a shower and wear freshly laundered clothes. Put on latex gloves and wash them down with a water/bleach solution or Isopropol alcohol between completing each bag. Disinfect the surfaces you will be working on and sterilize the air twice with a misting bottle containing a 10% bleach/water solution (be sure to avoid breathing in the mist).
  7. Only use fresh, high-quality spawn for inoculation.
  8. To inoculate the substrate, use the sandwich spawn method by layering straw and spawn seeds.

To avoid cross contamination, be sure to rinse the puncturing tool (pocupine quil) with a bleach solution between each bag. Using this tool, puncture the completed bags with 30-40 holes on average. Once the bags have been punctured, place them in an incubation room with a consistent temperature of 21°C.

After a period of incubation lasting six days, the smaller bags used for testing purposes were completely covered in white mycelium with no visible signs of contamination.

The mycelium seemed to run with extra vigor through this substrate. (This may be a result of the added calcium)


The below pictures were taken 5 days after placing the bags in my grow room.


Tomorrow, on day 11, I will start harvesting the first oyster mushrooms from these bags. (Total – 20 DAYS to harvesting my first flush)



There are some large oyster mushrooms that are ready for harvest on the second flush. Thus far, we harvested 14 kg of usable mushrooms, with more expected to come.