I’ve been posting this on reddit, so forgive me if you’ve already read about it…
I have long had an interest in trying to grow my own mushrooms, but recently started doing a lot of reading to learn the process. I had intended to start out growing a couple types of oysters on cut straw, but while I was collecting supplies and waited for spawn to arrive I ran across an article talking about cutting up clean cardboard, boiling it to sterilize, and seeding it with chopped mushroom stems. I figured this would be a great way to practice and see how much contamination I would get.
Besides the oysters, I wanted to also try cremini/button mushrooms. One of the local grocery stores has them in a bulk bin which appears to not be processed, and it allowed me to pick out some that looked like they came straight from the ground with obvious signs on mycelium still on the base. Great! So I set everything up, drilled some air holes in a small food container, added the cardboard and stems, and put it away in the closet. And then a couple days later I read that creminis actually want a rich mixture of manure and/or grain to grow on. Well crap…
The point was still to watch for contamination though, so I let it continue. A week passed without contamination and I was happy that it appeared I had cleaned things pretty well (and we’re talking a very hasty setup on my kitchen countertop in open air). On Sunday, I spotted some white fuzz. Oh boy, this could be it, the experiment is almost over. But then I checked on Monday… and it’s not just fuzz, I have actual STRANDS growing across the cardboard. Could it be?!?
Well, today it’s still looking pretty promising, and I’m seeing more coming out from various points in the cardboard. It’s hard to get a good look at everything because of the humidity, but today is day 12 since I set up the container and there are no greens, blues, or reds anywhere. I am hopeful, although frankly amazed at what seems to be happening.
In the meantime my oyster spawn arrived but it was less than expected so I have picked up some quart jars and am waiting to receive some rye grain. I have blue and pink oyster spawn which I will split between two jars each to expand before trying to move it to grow bags with straw. It will take a little longer than planned but I’ll get there. And I’m waiting for my container to be fully colonized with the unexpected spawn (or to see a definite sign that it is NOT mycelium) and then I’ll get that transferred to a grain jar as well.
However it goes, I’m having fun!
RE: the rye grain… yeah I agree that was way expensive! I’m not doing anything in bulk though and don’t really have the space to go crazy with all this, but at the moment I haven’t even been to the local stores to see what’s available. The popcorn should be real easy to come by, though. One thing I did see, though, was adding gypsum to the water while cooking, which is supposed to help prevent the grains from sticking to each other. It looks like they’re suggesting about one tablespoon of gypsum per 5 full quart jars of dry grain. I wonder if this would help with the popcorn too?
So a couple questions here about the popcorn… If you cook it in the pressure cooker, is that done inside the mason jars or just directly in the pressure cooker with some water? I have one of the big ones for canning, so it seems like cooking directly would be more efficient just in a regular pot, and I’m guessing since you are trying to cook them at this stage you’re talking about doing it this way.
And for either method, do you add enough water to completely cover the amount of kernels you put in the pot, or do you only put a little bit of water in the bottom? And while the kernels are drying afterwards, do you do anything to protect them from picking up any contaminants?
So this morning’s viewing of my cremini spawn… whatever is growing in there is definitely expanding. I’m seeing long white strands on all four sides of the container now. I think I’ll try to hit Walmart today to find a tub I can use to make a still-air box so I have at least a little control over contamination when I transfer my various spawn to the jars. Hoping to get some jars going this weekend.
I do add some gypsum some times, and sometimes I don’t add it. I think the main benefit is nutritional in that it adds some calcium. It can help dry out the surface of the grains a bit if you add it after cooking the grain, but it only helps to a degree - if your grains are over-hydrated or too wet, gypsum will not be enough to stop them from becoming a hardened block.
As for pressure cooking the grain - this is done with the grains directly in water with more than enough water to cover them. I use the pressure cooker in this step just because it is faster and more efficient. The rate at which grains absorb water is proportional to the temperature, and the liquid water gets hotter in the pressure cooker due to the increase in boiling point at the higher pressure. This rate depends on the pressure achieved by your pressure cooker (usually 12 PSI or 15 PSI), and a bit in the altitude. That’s why the best is to test the hydration with your setup instead of relying on a set recipe.
There is no need to protect the kernels while they dry. The sterilization step comes after, once the grain jars are prepared. In theory you can get unlucky and an heat-resistant endospore could land into the drying grain, so you might want to be a bit clean. I personally I just let it dry by the sink. Get them out as soon as possible while they are hot because this helps the water on the surface evaporate quicker. You can even use a towel to dry them but I find that rubbing grains with a towel is a bit awkward.
That’s great! Exciting :D Good luck!
Random trivia: it’s actually not the liquid water that matters, it’s the water vapor due to the pressure-temperature relationship of water in the gas phase (since gasses are significantly more compressible than liquids). It’s also important to note that water vapor does not behave like an ideal gas above ~1.5PSI, and it has a different temperature-pressure curve than gasses like N2, O2, and CO2, which is why you need to purge air at the beginning of the canning process in order to achieve a high enough temperature.
…and yeah, it’s crazy how altitude and atmospheric pressure matters, the weight of the air around us is literally pushing down on the rocker weight, affecting the relative internal pressure.
Thermodynamics is pretty awesome! XD
OK I guess I’m a bit confused then… if I cook the kernels in a regular pot for an hour, then let them dry for several hours, what is the sterilization? I thought from your previous description that the cooking step also sterilized them, and then once they were sufficiently cooled and dried I scooped them into a clean jar with some spawn and sealed up the jar?
I used to have a small pressure cooker that fit on the burner, but my ex took that with her. The canner I have will easily do 15+psi and hold it for hours, but this thing is huge… I think it holds something like 18 quart jars?
Ooh wow, yeah that’s a big pressure canner! I work with a smaller pressure cooker - the kind used for preparing meals (a 6L and a 10L, 12 PSI). You probably don’t want to use such a big canner for cooking the grains. I would just boil them them in a regular pot instead.
Usually the procedure is separated into the ‘hydrating’ step and then the ‘sterilization’ step, because this way you can ensure that the grain is hydrated to the right amount, that it is evenly hydrated, and that the surface is dry. It is possible to mix the dry grains and the right amount of water inside of the jar and then just let the grains hydrate while you pressure cook them. Some people online say that they use this method, but I did not get great results when I tried it.
For the sterilization you really should use that pressure canner. Placing the jars inside the canner and running it at 15 PSI for 90 minutes (after venting for 10 - 15 min) is enough to sterilize grain.
But what you have is indeed a big canner… If you don’t want to use it, you can try to simply sterilize by boiling both the grain and the jar. In that case I would not worry about drying the grain at all - the grain would go straight into the jar while both are still hot. Then you have a reasonable chance of not having contaminants. With this procedure you might have grains that are too wet and heat-resistant endospores of bacteria that can survive boiling, so you may get bacterial contamination. But is not a certainty - many times it works fine. Do what’s simplest, and if your contamination rate is above the level that you find acceptable then you can take steps to improve your process.
Yeah apparently I WAY overestimated the size of the canner. It actually holds 20 pint jars, or 7 quart jars. Haha oh well. The popcorn expended more than expected so I ended up making four quarts and still tossed some out, but the squirrels will be happy. So I have another half hour under pressure and then I can shut it down for the night (and my back is killing me!)
Well you learn through experience!! I find it useful to write observations like this in my electronic notes. In the short term it might feel like you will remember how much the popcorn expanded forever, but you might not use popcorn again for a year or two and then choose to try it out again - and then it can be helpful to look back at your popcorn notes and remember what you experienced!
Good luck transferring the mycelium to the grains!
I actually do have a text file open for my various mushroom notes and had written up a section for preparing both grains. I didn’t expect to remember all the steps my first time through, and wanted to note the differences. I ended up with about 1 pound of dry popcorn filled each jar about 2/3 of the way, and I don’t know how much the mycelium will further expand it, but it will be a good formula to work from in the future.
Oh and the gypsum appeared to work nicely. After cooking the grains and laying them out on a pan to dry, I stirred them a few times and nothing was clumping together, so that’s promising. I don’t think I’ll have a chance to transfer the spawn tonight but I’ll get arm holes cut in the still-air box and do the transfer tomorrow.
OK I’ll play around and see what I can make work. Considering I seem to be having good success with the cremini spawn (which was literally just bringing the cardboard and water to a boil and then laying out on the countertop to cool down for about 30 minutes) I’m hopeful that I can pull this off too. I live near Denver Colorado so we’re quite high with a pretty dry climate usually, but we’ve been getting a LOT of rain this Spring so I figure the risk of mold spore is a lot higher that normal.
Anyway thanks for all the advice! Hopefully will be posting pics of some nice grain spawn in a few weeks!
Good luck! I look forward to your healthy grain spawn pics!
You may be seeing pics faster that I expected! It’s been two days since I transferred my original spawn samples to the grain jar, I checked them today and the mycelium is already starting to spread to the grain. I was really expecting to need at least a week or more before I saw any definitive growth, so apparently they are happy.
I do have one jar of popcorn I am concerned about though. That one has little white dots all over the kernels throughout the jar, while all the other jars the kernels are still nice and clean. I’ll be watching that one closely to see what happens, although I’m not sure what would have caused contamination in that particular jar. It wasn’t even the last jar I loaded up. Maybe I’m getting worried over nothing, but I’m sure I’ll probably know in a few more days.
Considering this nice growth, I think I’m going to go ahead and transfer my cremini spawn to its grain jars this weekend. I’m getting nervous that the longer I wait, the greater the chance of getting some contam through the air holes.
Great!!
Hmm, that is suspicious. Did you inoculate using a liquid culture? If you spread the liquid culture throughout the grains, it could look like that… But if your inoculant is more localized (spawn, agar, or tissue) and the whit spots appeared all over the grain, you might not be so lucky 😰
Inoculation was done via grain spawn. I had received 10 grams of spawn from ebay. The spawn itself seemed fine, this was for pink oysters which I split between one jar of popcorn and one jar of rye. The jar of rye is still clean and the spawn is growing in both jars. The white spots actually reminds me of something I see occasionally on fresh sweet corn (which I believe is another type of fungus?), but it just seems weird that it is only appearing in this one jar.
I checked again this morning, the white spots are still there but haven’t gotten any worse, and the oyster spawn is growing. Maybe the oyster spawn will out-compete whatever the white spots are? I know contamination isn’t supposed to get through the fiber stuffing in the jar lid but I went ahead and moved that jar away from the others to reduce the risk of spread… just in case.
A cheap and easy method for expanding spawn is Lipa’s Tek. Renegade Mushrooms goes over the method in this youtube video: https://www.youtube.com/watch?v=HD_k-dAyE5Y
Basically a 40 pound bag of Hardwood Fuel Pellets (make sure they’re hardwood) can go for around 6-7USD. If you’re in a pinch, want a specific species of tree, or want certified organic, you can find hardwood pellets for smoking meats that go for somewhere around 0.50USD/lb in 20-40lb bags.
The reason this method works is that fuel pellets have less sugars and starches, and they are already partially pasteurized in the pellet press. So, as long as your pellets are stored well, a two-hour pasteurization at 200F is more than enough to get rid of most of the competing organisms. This is especially true of Pleurotus sp. (the Oysters), and from what I’ve heard, Hericium sp. (Lion’s Mane, etc), but I’m currently waiting on some Pholiota adiposa (Chestnut) to fruit that seemed to do well in pasteurized HWFP.
Give it a try, it’s a lot cheaper in terms of dollar cost, energy use, and time than wet-sterilizing in a small Pressure Cooker–but it’s best for expanding from spawn into more spawn or for bulking. You won’t get the same sized flushes as with something like grain or Master’s Mix, but you can easily whip up a lot more substrate–so it all comes out in the wash. I just retired 6 spent bags of P. ostreatus and they all seemed to do pretty well, and fruited more than once.
Nice, I’ll have to check out the video after work, but I’ve heard of using the hardwood pellets and there’s plenty of places around here that sell supplies for smokers. Once I get something going for my current spawn, lion’s mane is the next thing I want to try out. I just got my oyster starts transferred to grain jars yesterday so I’m making slow but steady progress.
Although now I think maybe I’m confusing the terminology? For mushrooms, does “expanding” refer to the process of growing out the spawn so you have a suitable quantity on hand, or is that the final stage of growing the spawn in fruiting containers? I’m currently at the stage of taking a very small amount and growing it out so I have enough on hand to get fruiting bags of straw started.
When I use the word “expanding”, I am referring to “increasing in volume”. So you could just “expand your spawn” (making more spawn), or “expand to bulk” (inoculating your fruiting blocks). Oh, and definitely try to find actual fuel pellets if you can, they’re usually much cheaper per pound than food-grade BBQ smoking pellets. I have found the basic fuel pellets at stores like Tractor Supply Hardware, but you have to ask an employee to check the stock in the back (since they’re out of season).
If you do end-up buying hardwood smoking pellets, be wary that some smoking pellets can contain additives like molasses, which means too much sugar for basic pasteurization with Lipa’s Tek–so always check the ingredients with smoker pellets.
Ah cool, thanks for noting the differences. We have Murdoch’s farm supply just a few blocks from my house, so that makes it easy to check. And cool, so “expanding” pretty much refers to ANY of the processes of increasing your mycelium. I mean it’s logical, but terminology for many things is usually extremely specific and rarely logical. I always figured that was the reason PCMCIA adapters for computers never caught on – nobody knows WTF it’s supposed to mean! :)
Looks like I’ll be prepping my grain jars tomorrow. The rye showed up in the mail yesterday and I picked up some popcorn kernels today. I have both rinsed and soaking in water tonight, the goal is to make three jars of each to I can try all three types of spawn in both types of grain. I also picked up a storage bin that I think is about the right size to make a still-air box. So the plan tomorrow afternoon is to get both grains cooked, loaded into jars, and sterilized in the canner, then let them cool overnight and I’ll get my spawn added to the jars Monday after work.
Oh, and the oyster spawn I got off ebay, they have both taken off like crazy sitting in the closet, so should be ready to go for the jars. The cremini spawn is still growing, but very slowly. I think that stuff is going to be a lot happier once it gets put in the grain jars, but at this rate it’ll probably be another week or two. Still, I’m excited that things are starting to progress!