Straw Pasteurization

This page presents a few video clips from the straw pasteurization chapter in our Let’s Grow Mushrooms 2 DVD set. Straw is an excellent and cheap substrate that performs well with a wide variety of mushroom species. While straw is perhaps best known for growing large and tasty Oyster mushrooms (P ostreatus), other species such as P cubensis also thrive on straw.

It’s important to use straw and not hay. Hay often contains the tops of the plant with the seeds still attached, which will easily contaminate with green molds if used. Straw is also prone to green molds, thus we pasteurize before inoculating with our mushroom spawn. Even with proper pasteurization, as shown in this chapter, straw will naturally begin to contaminate with molds within two weeks or so if not fully colonized. Therefore, it’s important to only use aggressive, fast colonizing species/strains with straw, and to provide the correct conditions for colonization to ensure the project is fully colonized within the 2-week time frame you have available.

   here's a few clips from the straw pasteurization video.

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Straw must first be chopped and hydrated. This chapter begins after we’ve chopped the straw into 1cm to 7cm pieces or roughly 1” to 3” lengths. If you’re doing a large quantity of straw, invest in a chopper. If you’re growing at home, you can place the broken up (from the bale) straw into a clean trashcan or other container, and then go at it with your weed eater. Other growers might lay it on the driveway or yard and use the lawnmower. Any method you devise to get the straw chopped up will be fine, just don’t waste your time trying to grow mushrooms on the long pieces you’ll find when you break up the bale.

We hydrate the chopped straw in a container of warm, soapy water. The warm water and soap are optional, but I’ve found the warm water hydrates the straw a tad faster, and the soap helps to kill off organisms in the straw. I use whatever brand of antibacterial dish soap I happen to find beside the kitchen sink that day, and add about the amount I’d use if washing a load of dirty dishes that size. Push the straw into the soapy water and agitate it with your hands to work up a nice foamy lather. Allow it to sit for two to four hours.

After the soak, pasteurize as shown in the video for an hour, then remove the straw and allow it to drain until cool. Once cool, it’s ready to spawn.

Enjoy the clip
Marc R Keith