How to Grow Your Own Mushrooms With Sawdust Blocks

(Psst: The FTC wants me to remind you that this website contains affiliate links. That means if you make a purchase from a link you click on, I might receive a small commission. This does not increase the price you'll pay for that item nor does it decrease the awesomeness of the item. ~ Daisy)

If you’re looking to bump up your food production during the winter months, why not consider learning how to grow mushrooms with sawdust blocks? This is a fun and easy means of putting some extra food on the table even when nothing is growing outside. Want to learn more? Read on.

Why sawdust?

Mushrooms are commonly cultivated on a supplemented sawdust substrate that’s been made into blocks. Many, many species can be grown in this way, from oysters to lion’s mane to shiitake and more. Our mushroom course gives one recipe along with instructions for making these blocks, and I’ve learned a few finer points along the way. I’ll discuss those points in this article. 

With respect to recipes, there are quite a few out there. The one given in our course is pretty standard: oak pellets + wheat bran + water = supplemented sawdust block. Stamets adds gypsum to his; one teaspoon per 5-pound block. Gypsum is a metabolism enhancer, much analogous to humans drinking caffeine.

Another recipe tweak is using what’s called Master Mix, aka Fast Fruiting Mix. This is 50% oak pellets and 50% soy hulls, available in bulk from stores such as Mushroom Media Online. Having worked with both, I find the fast fruiting mix worthwhile. Remember, mushroom mycelia don’t compete well with contaminating organisms. Therefore, the more quickly the substrate is colonized, the less chance of mold settling in. Using a fast-fruiting recipe and some food-grade gypsum can give your species the edge. Heavy inoculation of your substrate can also help. 

How we make our bags matters.

In addition to having a good recipe, there’s a matter of technique. Plan ahead: do you intend to inoculate using grain spawn or liquid culture? If the latter, then you can try pre-sealing the bags before sterilizing them. Be aware that the bags can burst during this process, however!

My research showed about half of the posters reported bursting, and half were fine. I use 6-micrometer thick bags and pack them tightly in my canner, so I’ve been fine. Fold your bag such that the filter is on the inside of the fold and won’t be submerged in water.

Those jar rings I use to keep my bags from direct contact with the bottom of my canner have been oxidizing and making an ugly mess! I don’t want any of that in contact with my substrate. Thankfully it scrubs well between uses.

Also, be sure to deflate your bag as much as possible while folding.

You’ll re-inflate at the point of inoculation so the mycelia will have the oxygen they need to grow and make mushrooms. 

A standard food sealer such as a Nesco or Food Saver will work well to seal bags, whether it’s done before sterilization or after. Wipe the inside of the bag so it’s clean of those sawdust crumbs that happen. I use a paper towel sprayed with alcohol. Also, dry plastic seals better than wet. I have my sealer set to Extended Seal. While rubber bands can work to close your bag, I find this works better. 

Self-healing ports can be anything from a piece of micropore tape to a fancy reusable rubber gizmo similar to what’s used in a specialized lid. I prefer the simple route myself. Be aware, however, that the humidity inside of your tent will likely dislodge a lesser glue, giving contamination a way in. Done this, been there. Use tape with a good glue and cover your injection site with the same. Silicone will also work, but you’ll have to wait 24-36 hours for it to set before use. If you’re flush with cash and don’t mind the expense, bags with ports are available from several sources.

If you’re planning to inoculate from spawn, you’ll need to leave the bag open during sterilization. One thing you can try if you’re doing everything right but still having a problem is a Tyvek sleeve. These are available on eBay in several sizes and fairly cheaply. They look and feel like thick coated paper. Put them on top of your block inside of the bag before sterilization. The rationale is that anything entering your bag when you open for inoculation will hit the sleeve, therefore not embedding into your substrate. Be sure to remove the sleeve within your still air box before inoculating your bag. And yes, they’re reusable. I rinse mine off and store them once dry with the rest of my small items. 

(How do you survive a winter storm? Will you know what to do? Check out our free QUICKSTART Guide to learn more.)

Inoculation is an art form.

Ah, inoculation! The art of introducing the desired species to substrate that’s also a major point where contamination can be introduced. It can happen even while using a still air box. This is why I wipe all of my surfaces with either alcohol or bleach repeatedly, including between bag inoculations. I also leave my bags in the canner until I’m ready to inoculate. Remember: hot substrate will kill your mycelia. I leave my bags to cool inside the sealed canner overnight. A thermogun is also helpful. 

There are two ways to inoculate: liquid culture and grain spawn. If you followed my instructions and made your own master cultures, you’re in a great position to use liquid culture. This is one way to lower the odds of contamination: just inject via the self-healing port, tape it over, and watch the bag colonize. Be aware that it’s still possible for bags inoculated in this way to become contaminated, however. Too high humidity in your Martha tent or mold endemic to that area can and will do it.

Done this, been there. In fact, for a time, every one of the ten bags I made became contaminated. It happened so fast I thought that spontaneous generation wasn’t so debunked after all! It turned out that both too-high humidity and endemic contamination were at fault. I now bleach out my tent regularly, about once per month, and adjust the humidity to 75%. I have four species fruiting as of this writing, and they’re delicious! I tend to inoculate heavily, using 5-10 ml of culture. The culture won’t last forever anyway, so it might as well be used, especially if you can give your desired organism an edge. 

Inoculating from spawn most definitely needs to be done in a still air box. Video instructions for doing that are contained within the course. Stamets also shows this being done in his book. Basically, just shake the spawn into the bag, then seal the bag.

I find it helpful to use a sanitized butter knife to break up the spawn before shaking, as I find the spawn inside of the jar becomes a tight mass during colonization. Have an alcohol wipe or paper towel soaked with alcohol inside of your box. I wipe my blade between uses, even in the same jar, and wipe the spawn jar lid and upper jar area before closing if I haven’t used all of the spawn. Because still air boxes are small, I inoculate one bag at a time and sanitize everything between bags. 

(Want uninterrupted access to The Organic Prepper? Check out our paid-subscription newsletter.)

So that’s it!

A few practical tips for making and inoculating your own supplemented sawdust blocks. Who says gardening can’t happen during a subzero winter!

Do you grow mushrooms yourself? Have you learned a few things along the way? If you’re not growing mushrooms, what’s stopping you? Do you have questions? Please share your tips or ask in the comments below! 

About Amy Allen

Amy Allen is a professional bookworm and student of Life, the Universe, and Everything. She’s also a Master Gardener with a BS in biology, and has been growing food on her small urban lot since 2010.

Picture of Amy Allen

Amy Allen

Leave a Reply

    • Give me a break.

      There’s tons of information without buying the course. That doesn’t negate the information that is there. There is not a single thing wrong with a shoutout to something more in-depth for those who are interested. Nobody is holding a gun to your head to buy it, Mr. Sour Grapes.

      By the way, I have a course on reading something without making unnecessarily mean comments. Want to buy it?

    • We don’t need that here.
      Bet you could not answer simple questions on what was in the article.

      This was a primer, not a treatise.
      Buy the book and do some research.

      And use spell check.

  • Mushrooms will grow in a lot of substrates. The sterilization is very important, so try not to skimp on that. Ive grown shrooms in toilet paper rolls, once just to see if it worked, I used the parchment ‘sheets’ that bamboo trees drop off. I put some innoculate in there with some sawdust, and shoved two pieces of wadded up TP in the ends to keep it from falling out and sure nuff, got oysters out of it. The mushrooms will consume your substrate though so you may get one or two blooms out of it then you are done. It’s time to hunk it all into the compost bin then. You can also dry these shrooms easily enough too for long term storage if you don’t want / need to eat them all at once either.

    • Yup! I’ve seen oysters grown on toilet paper rolls. They’ll also grow on straw, which lions mane won’t. The buttons, like portobello, prefer finished manure. Like plants, each species has its preferences. That’s one of the things that makes growing them fun!

      And yes, I dehydrate what I can’t use right away. Fresh shrooms simply do not keep long! I’m making some lion’s mane tincture now and had to dehydrate the other half for the water bath step because the alcohol extraction takes 4-6 weeks and there’s just no way the shroom would be good.

      • I get TONS of lions mane this time of year. I got a huge one the other day. It’s funny, when it’s dryer out they are fairly light but when its damp, the same size one can weigh about a pound, they can suck up a HUGE amount of water. I slice them and fry with onions / garlic, whatever they are wonderful. The rest I slice and freeze dry. Yes I know I can brown bag it and let them dry but with them since they are so big, I like to dehy so I know it’s finished and they don’t mold out.

        Im lazy… what does the tincture do for you? .. ok curious and lazy 🙂


  • You Need More Than Food to Survive

    In the event of a long-term disaster, there are non-food essentials that can be vital to your survival and well-being. Make certain you have these 50 non-food stockpile essentials. Sign up for your FREE report and get prepared.

    We respect your privacy.
    Malcare WordPress Security