Pasteurizing Substrate for Edible Garden Beds

I’m a bit behind in updating the blog, it’s been a busy couple of weeks…

We’ve done two home inoculation projects this spring, a small project a few weeks ago and a larger project yesterday, in addition to the 100 log inoculation in Brown County, Indiana – and of course attending the Brown County Morel Festival

Project #1

A few days before Easter the kids were over and I decided to test out an artificial grow log system. I had a little Stropharia spawn, a few cups of Shiitake spawn and a half a bag of Oyster spawn that was left over from the Brown County, Indiana inoculation project on Tom Westgard’s small scale farming operation. With my 17 year old daughter and 8 year old son we put up the two largest stockpots with water and began to bring them up to temperature. Once they hit around 170° f we added wood chips to one, and burlap sacks to another.

We brought the stew of wood chips up to temperature, kept between 160 and 180 for about an hour, drained and let cool. The burlap sacks were hung on the neighbors fence to cool and the chips were spread in a clean plastic tote to cool. Once cool we spread out one burlap bag and sprinkled two cups of wood chips and four of mixed ground and unground, fresh roasted coffee for the Oyster, and only wood chips for the Stropharia and the Shiitake. We then inoculated and rolled them tightly as we could and slid them into 4 inch HDPE drain tile and covered the ends and holes with Tyvek. I checked them yesterday and all show signs of mycelium running to the ends in the center.

Pasteurization is very different than sterilization: With pasteurization you’re attempting to bring down the level of contaminants, while leaving alive beneficial bacteria. Sterilization kills everything, and is quite useful, especially when you’re producing fresh spawn from spores or live culture plates, but unless you’ve got a clean room with laminar flow hood you’re only going to produce black mold. It’s important to remember that if you’re pasteurizing, don’t let your substrate come to a boil — without the beneficial bacteria and molds you’ll open yourself up to serious contamination. 

Project #2

I also had a bag of Pluerotus pulmonarius left from the Brown County project. With all living things you’ve got to use it — have it make mushrooms —  or give it more food by inoculating more substrate with it. Yesterday I ran three of the largest stock pots pasteurizing chips and burlap on the stove top. I made a complete mess of the kitchen with bags and wood chips everywhere, but when I was done cleanup took just 20 minutes. I drained the wood chips into another pot, and let the burlap to drip into that pot before I hung them back up on the fence in an attempt to conserve as much hot water as I could.

I laid the chips out on a clean plastic tarp to cool. I soaked some whole roasted coffee beans in the sugar syrup, it was actually 3 tablespoons of sugar to 1/2 gallon of water and 2 cups of whole beans. I added this nutrient rich whole bean directly into the wood chips.  If you can manage it the best time to inoculate the wood chips is when they just cool to about 80 degrees, the optimal incubation temperature for the spawn. If your chips are cooled to a lower temperature  inoculate and package. Wasting coffee on growing mushrooms might sound crazy but a local coffee roaster not only gives me their coffee sacks but also all of the fresh roasted ground and beans that they use in testing. It’s not for human consumption, but Oyster mushrooms love the energy packed into it.

Temperature for Pasteurization holding between 160° and 180° f.

Temperature for Pasteurization holding between 160° and 180° f.

Remember during the inoculation process you want to be sure to minimize the amount of time the pasteurized substrate is exposed to open air. You’ve just killed off most of the competitor fungi, allowing them to jump onto your chips through the open air doesn’t help anyone.

Cooling to ~80° f. for inoculation

Cooling to ~80° f. for inoculation

This time I spread about a large handful of spawn into each 26″ c 48″ bag and folded it over, and added about another cup of spawn and tightly rolled the sack. I laid the rolled bags in the bottom of a plastic tote, after adding a small amount of spawn to the bottom, and sprinkled a little spawn between layers. For the chips, once cooled, I moved the chips to a tote, and added spawn. I wound up running three pots of chips and three of burlap bags. When I was done with the bags I spread a little inoculated wood chips into the crevices and open spaces in the tote. 

Pasteurized and inoculated burlap bags to be used as base for Mushroom Gardens

Pasteurized and inoculated burlap bags to be used as base for Mushroom Gardens

This project is set to produce enough wood chips and burlap bags to put in two mushroom garden beds. The myceliated burlap will create a barrier between the ground and the raw wood chips that will be mixed with the myceliated wood chips. 

I’ll check the spawn in about a week, taking a quick peak to be sure that the mycelium in running and I’m not fermenting the chips. 

Throughout the spring, summer and fall we’ll be putting in edible mushroom gardens, Oyster Mushroom, Elm Oyster, King Stropharia, and Nameko are all great wood loving bases for garden beds. Some pair extremely well with particular plantings, bringing nutrients to the root ball in exchange for sugars from the plant essentially extending the size of the root ball and acting like a natural fertilizer.

If you’d like a consultation on your garden needs just give us a call!

UPDATE: Just checked the chips and burlap totes, all seem to be running pretty well.




2 thoughts on “Pasteurizing Substrate for Edible Garden Beds

    • Hey Bruce,

      I’ll keep everyone updated on how the spawn is running, and I’ll be sure to post pictures of the experimental artificial logs as they run.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s