Mushroom Cultivation: Straw Bucket Tech

There are so many different ways to grow oyster mushrooms it’s almost but not quite unbelievable, so do yourself a favor and please don’t for an instant think that this is the only way, or necessarily the best way, to go about the process. Oyster mushrooms (Basidiomycete fungi of the genus Pleurotus) are an incredibly adaptable and resilient bunch that can perform well under a comparatively wide range of growing conditions that would be completely inappropriate for other varieties of edible and medicinal mushrooms.

This makes the many different species and varieties of oyster mushrooms an excellent choice for those of you that are new to the world of growing mushrooms. I go into the reasoning behind this in my previous article on oyster mushrooms which also goes into depth about how you can literally grow the darn things in soaked cardboard. Today we’ll be looking at straw and how this can/could be used as a substrate for fruiting your oyster mushrooms.

Straw is a cheap and widely available material (especially if you live out or near the country) that is excellent for growing oyster mushrooms. There are many, many success stories out there to authenticate this claim. Straw can be heat treated (pasteurized) or fermented, left to drain and cool, then mixed with oyster mushroom spawn and stuffed into perforated plastic bags or plastic bins, buckets or trays with holes drilled into the sides.

If you can think of it, chances are someone has tried to grow oyster mushrooms in/out of it. Just because we exist in this grand age of the internet, check out this photo of oyster mushrooms growing out of the side of a house (which is definitely not a good thing for your house) and these ones growing in a pair of old shoes. I highly encourage you to explore your options using the materials that you have on hand. You probably have something lying around that would be at least decent at the task of housing and fruiting oyster mushrooms.

Now that you are aware of the options that are out there (or that you can create your own options) let’s talk about how you can grow oyster mushrooms out of a plastic pail or bucket. This procedure is very simple and can easily be adapted to suit any large, stiff plastic bin or tray. It’s best if the container has a tight fitting lid to seal in moisture and seal out light, debris and ‘baddies’. If this is unavailable then you will have to find something to seal it.

STEP 1: PREPARING YOUR STRAW

The straw must be ‘cleansed’ of all of the diverse microbial life that it is currently hosting even in it’s current dry state. Make sure to be using straw that is brightly colored, fresh and dry. Your straw should definitely not be soaking wet, stored outside or have a moldy, rotten smell. Any sort of straw will work; wheat, barley, rye, oats and even many species of wild grasses, which I talk about about in my previous article. There are two main methods on how to prepare your straw.

DSC_1754

Pasteurizing the chopped and cut straw on the stove. It helps to have a weight on the top of the straw to keep it submerged in the water.

Heat Treating, also known as pasteurizing, is one way to go about it and seems to be the most popular of the two options likely because it tends to produce better results. Simply place your straw into a pot of water (filtered or well water is best) and heat the water until the temperature is around 180°F. Turn down the heat and keep the water hovering around this temperature for at least an hour, two hours doesn’t hurt. This heating is enough to kill not all but most of the micro-organisms on the straw.

One does not want to completely sterilize the straw, as sterilizing wipes out the small amounts of micro-organisms that remain after pasteurization. You want to have a few microbes left because these will help prevent ambient spores and organisms in the air from colonizing the substrate and competing with your mycelium. ‘Baddies’ face a bit of resistance from the resident microbes which helps tip the scale in your favor. It’s also more than likely that the microbes actually directly benefit the mycelium by helping it to acclimatize to small levels of competitors in it’s environment, just like getting a vaccine.

Fermenting is the least energy intensive option but as I mentioned it is not as successful as heat treating your substrate but can still be very effective. It’s also a slower process. Begin by submerging (with a weight) your straw underwater (again in non-chlorinated filtered or well water) and leave it like that for 2-3 days. This will kill off most of the aerobic micro-organisms on the straw. Then, remove the straw from the water and allow it to drain. When the straw was submerged, it likely became partially colonized by anaerobic micro-organisms. Most of these are killed when you remove the straw from the water.

What you are left with is straw that now has significantly lower populations of both aerobic (oxygen-loving) and anaerobic (oxygen-hating) microbes. This procedure is probably best performed outside in the shade and somewhere sheltered from bad weather in an old bathtub, some dairy sinks that you may happen to have lying around or even a kiddie pool. Be creative and baffle your neighbors simultaneously.

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Freshly pasteurized straw cooling and drying on a metal tray. Laying the straw down in thin layers will help it to cool and drain faster than if you have to pile it up a bit. I would consider this metal tray satisfactory but less than ideal. A wire screen is probably best.

Time of course is key for both fermentation and heat treating, and your straw should be used immediately after it has drained for a few minutes and/or cooled to at least 100°F. Read on for some instructions on how to go about assembling your spawn and straw and what sort of maintenance it is going to need once you have finished assembly.

STEP 2: ASSEMBLING YOUR MUSHROOM BUCKET

After your straw has cooled down sufficiently and drained a little bit it’s time to begin placing it into your bucket/pail. My bucket has a 3 gallon capacity and I drilled my holes 6 inches apart halfway down along the sides using a 5/8” drill bit. This gave me 6 holes in total. These are necessary for air circulation and respiration within the growing environment and to allow a place for the mushrooms, once they begin developing, to fruit from.

Using clean tongs or very clean hands begin packing a 1-2 inch layer of straw into the bottom of the bucket. Next, scatter a 1-2 inch layer of oyster mushroom grain or sawdust spawn that you have purchased on top of the straw or gently tear and lay down some pieces of cardboard from your own glorious home made cardboard spawn. For the purchased spawn, it is best if you gently break the block up into fine pieces, as this is more effective than mixing large chunks of spawn into the straw.

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My bucket half-way full of straw and cardboard spawn. I would recommend for next time to tear the cardboard into smaller pieces than what you see here but being careful not to smoosh and damage the mycelium too much. Minimal but careful handling is best.

Continue this layering of 1-2 inches of straw and 1-2 inches of spawn until you either reach the top of your container or run out of materials. It is a good idea for your container to be most if not entirely full, as too much ambient air space in the container could lead to contamination. Contamination in a nutshell is when your intended mycelium has been compromised by the adventitious growth of other micro-organisms such as other fungi, molds and different bacterium.

Step 3: TAKING CARE OF YOUR BUCKET

Once you have reached this point you can close up your container/bucket nice and tight and bring it to it’s home for the next few weeks or months, depending on how quickly and thoroughly the spawn takes off into the straw and colonizes it. The best case scenario is 2-3 weeks. If you do not see any action after this period then it’s possible that you weren’t successful.

These methods that I am describing most mushroom growing hobbyists would probably disagree with, but for someone that is trying to grow mushrooms for cheap using materials that they probably already have these methods should work reasonably well. You might fail a couple times, but you get better at it and the whole process evolves along with your critiquing. These methods are almost universally accessible, which is a powerful factor for empowering individuals and communities to take control of their own food security.

Your container/bucket will also need a micro-habitat that is between 15-23°C and generally humid. Chances are the room that you are in right now is within that temperature range (if you are like me and only have a computer at home, not one that fits in your pocket) and so that is usually less of a concern. Humidity posses a greater challenge, but some wonderfully cheap DIY ‘growing chambers’ can be made from a wooden, plastic or metal frame with translucent plastic stretched over it. Cold frames are also excellent put to use in this fashion, such as this model which is small enough to put in the corner of a room.

It would help if there were a few holes in the plastic spaced every 6-8 inches apart, as growing mushrooms love lots of oxygen and to not like to have CO2 build up around them. The holes don’t even need to be that big, maybe a 1/2 inch or so. If your growing chamber has a lid that can be propped open then you don’t need to worry about holes. It’s also important that the plastic be transparent, as the growing mushrooms need indirect light in order to form properly.

The inside environment will need to be misted periodically as well, with clean non-chlorinated water. Warm containers of water could also be periodically placed and swapped out inside the ‘growing chamber’, providing consistent supply of moisture laden air around your mushrooms that will condense on the plastic inside. Having a layer or two of plastic underneath this ‘growing chamber’ will help for your floor to not get ruined by being constantly wet.

Ideally there should be beads of condensation on the inside of your little micro-climate at all times, but since we all like to do other things than take care of our growing mushrooms this isn’t realistic. However, depending on how often you neglect to check on the levels of humidity in your ‘growing chamber’ you may experience decreased yields or outright failure. So try not to forget about your mushrooms if you can help it. They won’t like you for it and will give you nothing in return.

For those of you that would like to invest a little bit more capital into this project, there are mini humidifiers that you can purchase that are intended for small spaces as well as small devices with digital displays which tell you exactly what the humidity level is inside of your mushroom enclosure as well as the temperature. All of these items are pretty inexpensive, and so if you think that mushroom growing may well turn out to be a bit of a long term hobby for you, then picking up these items might not be a bad idea.

Hopefully by this point, after waiting the 2-3 week incubation time and giving your mushrooms lots of fresh air and humidity, the substrate that you can see through the holes in the container have become covered in thick, healthy mycelium and may even be starting to produce clusters of baby mushrooms. This is known as pinning and signals the beginning of the fruiting stage. We’ll be looking at what to do when this happens in episode 3 of this program, which I hope to conclude sometime during the late spring or summer of 2017. Stay tuned and thanks for following along!

Updated 02.17.17

 

 

One comment

  1. very helpful as my project is going on.however the size of mushrooms am seeing is not the one i wanted.i wanted a bigger one which i got some last yrs. am learning also on use of cardboards.otherwise thank you

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