King Oyster Mushrooms on Sawdust

The Fruiting Block: Growing Gourmet Mushroom on Sawdust

Many types of mushrooms , specifically oysters, will do great and fruit heavily on straw logs as was explained in this post. However, most gourmet mushrooms will actually do way better if grown on hardwood sawdust supplemented with some sort of nitrogen rich supplement. Growing gourmet mushrooms on sawdust blocks will require a little bit more initial work than straw logs, and more equipment- mainly because sawdust blocks need to be pressure sterilized- unlike straw logs which need only to be pasteurized.

However, the process is quick, less mess, has lower chances of contamination, and provides a perfect medium for the mushrooms to grow large healthy fruits.

The basic recipe we use to grow all our gourmet mushrooms uses hardwood sawdust pellets, wheat bran, and water. Hardwood pellets are used because they are readily available at local retail stores or online, and store easily. Make sure to get hardwood pellets and not softwood pellets. Mushrooms do not grow well at all on softwood. The pellets are small and only expand when soaked in water. Wheat bran is used as the nitrogen rich supplement. It can be found in small quantities at your local grocer, but can be quite expensive.

A better option is to buy some from a feed or farm store. Oat bran can also be used, but we have found wheat bran to be the most effective. As for water, the trick is to add just the right amount to get a proper moisture content. You don’t want your block to be too wet or too dry. The following recipe works great for use, but you may have to adjust it slightly to suit the specific moisture content of you pellets.

The Fruiting Block Recipe:

For every 5 lb fruiting block:
5 cups of hardwood pellets
1.4 liters water
1-1/4 cups wheat bran

How To Grow Mushrooms on Supplemented Sawdust Fruiting Blocks

Step 1: Measure out the components

The above recipe will make a block weighing approximately 4 lb 4 oz. Your final bock should end up weighing 5 lbs after you add 12 oz of grain spawn. Its best multiple blocks at a time, as many as can fit inside your pressure sterilizer. This presto pressure canner is relatively cheap and can hold 4 large blocks, made with 20 cups pellets, 22.5 cups water and 5 cups wheat bran

Hardwood pellets for mushrooms.
Step 2: Add Water to Sawdust Pellets

Place your hardwood sawdust pellets in a large tote or suitable container for mixing. Add the correct amount of water and mix until the pellets have broken up into a loose sawdust texture. Adding warm water makes the sawdust break up much quicker but is not necessary, as cold water works just fine. It may take a while to mix up all the pellets, but you want to be sure it has all broken down because the mushrooms will have a much harder time breaking down the hardened pellets.

Step 3: Add Wheat Bran

Once the sawdust is mixed up and all the pellets are broken down, add the correct amount of bran. You can increase the amount of bran to add more nutrition into the block, but more bran will increase the chance of contamination and adding more will eventually lead to diminishing returns. Make sure to mix the bran thoroughly and evenly throughout the sawdust.

Mushroom grow bag.
Step 4: Add Mixture to Grow Bags

Weigh out the proper amount of sawdust/bran mixture and add it to a grow bag. I add 4 lbs 4 oz to each grow bag, which makes a 5 lb block once the spawn is added. Try to not get the mixture on the sides of the bag above the block, as this can lead to contamination problems later on. The bags are specially made for growing mushrooms. They are made of poly propelyne which can withstand the sterilization process. The Filter patch allows the mushrooms to breath while they are colonizing the substrate.

Step 5: Fold the Bags Down

The tops of the grow bags are gusseted and should be folded down in a specific way, with a filter fitted in between the gussets. This prevents contamination during cooldown after sterilization. When the bags cool down, air will be drawn into the bags. If there is no filter between the gussets, dirty air can sneak through and ruin your project. By slipping a filter in between the gussets you can alleviate this problem. Once the filter is slipped in, fold the top of the bags over a couple times. For the filter, you can use a cut piece of tyvek or a square cut from a painters suit.

Step 6: Pressure Sterilize

Load your pressure sterilizer with the bags stacked on top of each other. Make sure to use jar lids or something that will keep your grow bags from making direct contact with the bottom of the sterilizer, as this could cause the bags to burn. Fill with the water to just below the top of the bottom bag. You will need more water than when making grain jars because you will be sterilizing for much longer. Also, be sure to add a plate or something heavy to the top of the bags. If you don’t do this crucial step, you run the risk of the bag clogging the weight and the pressure relief valve on the pressure cooker. This could cause pressure inside the cooker to reach dangerous levels. Pressure sterilize your bags for 2.5 hours. This seems like a long time, but it is necessary for the heat to fully penetrate the the inside of the block and fully kill all contamination.

Sterilized fruiting block

A fruiting block post-sterilization ready to be inoculated with grain spawn. Notice how the filter patch is slipped in between the gussets and the top is folded over twice.

Step 7: Cool Down and Inoculation

Allow your fruiting blocks to cool down for at least 8 hours. I like to pressure sterilize at night and allow the pressure cooker to fully cool down over night. Anything over 38 deg C can potentially kill your mycelium. Fruiting blocks are best inoculated in front of a laminar flow hood. You can do it in a glove box or similar, but you will increase your chances of contamination. Once you have added grain spawn to your sawdust block, tie off the top of the bag with a piece of wire or zip tie and set on a shelf. Shake the bag to evenly distribute the individual grains throughout the bag. This will speed colonization of the block.

Grow bags colonizing

Grow bags colonizing on a shelf.

sawdust grow blocks

Grow bags after inoculation. Note the mixing of the grain spawn.

Step 8: Allow to colonize

Depending on the amount of spawn and type of mushroom you are trying to grow, it might take anywhere from 10-21 days for the mycelium to take over the block. There is no benefit to shaking the bag during colonization, just allow the grain spawn to take over the block naturally. Periodically look over the bag to check for any signs of contamination. Usually, it is not worth opening contaminated bags in your grow room, so it is better to just throw them out if the bags look contaminated.

Step 9: Fruit!

Once the bags have fully colonized consolidated, they are ready to fruit. Different mushrooms have different requirements from this stage, but for most gourmet mushrooms, just cut off the top of the bag and place inside your growing environment. From here, the block should start to pin from the top of the block, and eventually form mushrooms. Closely monitor humidity and temperature to see what your block needs.

yellow oyster mushroom on sawdustPink Oyster Mushroom on sawdust
Step 10: Harvest

Once you are satisfied with the size of your fruits, they are ready to be harvested and enjoyed. The best strategy is to cut the mushrooms off at the stem trying not to damage the underlying block, since it can be used to get 3-4 flushes if properly taken care of. Once harvested, simply place your block back into a fruiting environment and wait for a subsequent flush. Watch closely for contamination as your blocks gets older. Often new mycelial growth will take over the harvested portions of the block before a second flush arrives.

Thanks for reading and good luck with your grows!

-spread the spores-


Want to grow mushrooms at home? Here are a few things you’ll need to be successful.

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Russell Greene
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Russell Greene

Would a liquid inoculation be easier via hypodermic needle, rather than opening the bag up? Just like getting a shot at the doctors office. Clean the area with alcohol, flame needle, administer LI and then tape the tiny hole up. Then you could have successful grows without a flow hood, at least for a hobbyist.

John
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John

How bad of an idea would it be to put the premixed sawdust, bran and water in a pressure cooker without bags? I’m actually going the bucket and mason jar route to cut down on plastic usage. The only thing I worry about is the sawdust keeps expanding in the pot and could possibly clog holes, creating a potential bomb in my kitchen. I was just wondering if you may of done this or know someone who has successfully. Thanks

Bryan Schenk
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Bryan Schenk

Tony, What type of Hardwood do you suggest for Oysters?

Steve Fischer
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Steve Fischer

If you wanna do some outdoor Oyster Totems , Cottonwood works great !
You can seal the Cuts between the Rounds, and between the Cardboard and the first Round with wet Clay.
Also the Top of the Top Round seal with Clay .I just built a few more since my first Totem was an amazing success.
Very inspired Steve

Frank
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Frank

Man that sounds cool but I really need a visual cause I cant grasp it. Here in Texas where I live we lack a lot of Oaks but there is a ton of big cottonwood in river bottoms and I think this would be awesome…any links to a pic of how this is done? thanks

John Patrick Chonka
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John Patrick Chonka

Oak

steve Raman
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steve Raman

good day to all of you this is a excellent info thanks
all best from germany
steve

Jack
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Jack

Hi Tony,
why must sawdust be pasteurized by pressure and not temperature?
Also, what process would you recommend when pasteurizing coffe grounds?
Cheers,
Jack

Jack
Guest
Jack

∗Edit…
the coffee grounds have not been pasteurized in a coffee machine,
but rather have been used to make cold brew,
jack

Donald
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Donald

I live very close to a wood shop, they have truck loads of hardwood sawdust, could I us it instead of the wood pellets?

Mal Abbey
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Mal Abbey

Hello I have two questions for you please: 1. I have a small steam distillation plant for producing essential oils such as Cinnamon leaf oil. This is running at atmospheric pressure. I can direct and inject the steam deep into the middle of the saw dust bag using 2 mm bore copper tube … with a thermal lance arrangement. In addition I can expose the PP bags filled with saw dust to Ultra violet light too for sterilisation. Your comments would be highly appreciated on this sterilizer procedure. 2. What sort of moisture level or wetness do we have to… Read more »

Leo
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Leo

Hi Tony,

I’ve got a portobello liquid culture, can I use that to inoculate sawdust/rice bran/gypsum cake?
Or I need a specific formula for portobellos spawn?

English isn’t my first language,
Thanks

Sorcha
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Sorcha

You mention in step 4 “Weigh out the proper amount of sawdust/bran mixture and add it to a grow bag. I add 4 lbs 4 oz to each grow bag, which makes a 5 lb block once the spawn is added.”
But reading further you don’t mention when to add the grain spawn. Also in other recipes on your site the grain spawn is not mentioned. Is it necessary?
I am trying to find an easy recipe to start my first batch in jars and inoculate via syringe.

Wes
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Wes

Hi Tony, Love your site, Could you suggest more information on how to fold the bags in step 5. I think everything else was expertly explained.

Reza
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Reza

What kind of wood (sawdust), is good for Mushroom cultivation ?

Prashant
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Prashant

Hi Tony,

Thanks for the wonderful information. I am trying to start a mushroom farm in central himalayas in 2018, so am lapping up what all you put down on your site.
Is there any alternative to disposable plastic bags? They have already created a lot of pollution in India and I want to avoid them if possible. For oysters, I did read around a lot and think that reusable plastic buckets with holes punched in them is a good idea. I will be trying some sample runs next week. However, is there any way for growing shiitakes on any reusable containers?

Ben
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Ben

Hey Tony,

I’ve heard of some folks hydrating their Hardwood Fuel Pellets, and then inoculating them without sterilizing them before inoculation. Also, I’ve heard of other people pasteurizing the Hardwood Fuel Pellets, and then inoculating them. However, in your instructions you sterilized before inoculating.

How did you go about deciding sterilizing your pellets before inoculation was the best move? Can you achieve similar results by either pasteurizing, or by skipping the sterilization/pasteurization process all together?

everett smith
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everett smith

I run a small one person sawmill as a job at home and cut all oak.The sawdust is quite fine and would be better I would think than processed wood pellets.

David
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David

Hello Tony, I plan to grow lion’s mane soon and wonder if I absolutely need to use grain spawn in the filter-patch bags of hardwood sawdust? May I instead use pieces of bought colonized sawdust block? I’ve never handled sawdust block before. I have though in the past (with other kinds of mushroom) started from spore prints and done the whole nine yards, from isolation etc. all the way through to grain spawn or lc and fruiting- this took quite some time but was always successful. This is for a parent who had a stroke, and time isn’t a luxury,… Read more »

JR
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JR

Hi Tony,
I have a block of coffee grounds colonized with oyster mushrooms (from a grow kit). It is ready to fruit, but I was thinking I might use part of it to start some new sawdust blocks. Do you think it would be effective to add small pieces of the coffee ground block to the sterilized grow bag in place of grain spawn?
Thank you for sharing your growing process. It’s really good information!

Yarrow
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Yarrow

Hello mycological pals, I’ve recently purchased a few “back to the roots” oyster mushroom grow kits with the intention of using them as spawn to start my own blocks on coffee grounds. As you said Tony, get the most out of the grow kits. So my question is, how can I inoculate the coffee grounds using pieces of the already colonized sawdust blocks with little to no contamination? Roughly how much of the sawdust block should be used to colonize the grounds? Any and all advice welcome. JR- Essentially, I’m attempting the same thing as you, just reversed. I’m curious… Read more »

Mark Sv
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Mark Sv

Hi, Tony!

In some of the pictures in the Growing on Sawdust section, casing soil has been added to the top of the bag. What are your recommendations on making and using casing soil? I am playing with winecaps right now and I hear that casing soil makes a big difference.

Adam
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Adam

This page has alot of great info thank you! I was wondering if I could use this method of supplemented sawdust to inoculate logs or outdoor beds? Or does the added bran cause problems vs. straight sawdust spawn?

6sheds
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6sheds

So surely sterilising the bran in say a jar, and adding that with the spawn into pasteurised wood could be a viable alternative. Providing the addition is done in sterile conditions. That would reduce PC time and overall volume as you would only require to sterilise 20%. It would also allow blocks to be formed in totes which would reduce the need for single use plastics. I’ve just taken tissue cultures for shiitake so I will try this with a couple of blocks. I could use my steamer to sterilise the woodchip which is atmospheric pressure and PC the bran.… Read more »

Greg
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Greg

I was thinking along the same lines, I use wood pellets which are already pretty sterile to begin with so I would just boil the bran in water for an hour before mixing with the wood pellets and then transferring into bags. I am not sure it even has to be completely sterile, it has to be sterile enough to give the mycelium a good head start over anything else that’s in there then it becomes self regulating so perhaps going heavy on the spawn in such a situation is a good idea.

Jerry Neighbors
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Jerry Neighbors

Hi tony, thanks for sharing.new to all this but have tried oysters on straw from a bag of colonized grain spawn,i have in small plastic totes,but after 3 weeks nothing has changed ,any ideas,does it need to be in a dark area or light?

Channey
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Channey

Hi, Tony, My name is Channey I have recently become interested in growing my own mushrooms at home. I have been growing oyster on straw with some success. My question is How many pounds of oyster mushrooms should I expect to harvest from a 8 lb bag ( this includes moisture weight)? so far I am getting one flushing of about 1 to 2 lbs and not getting a second flush and Should I pull the plastic off of the Straw once pinning starts?

Terrance
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Terrance

Hey Tony,

I am attempting to grow Reishi and was wondering if you could layer the sawdust substrate with the grain spawn in pans to increase surface area for fruiting? Also is casing necessary? Thanks for the tips

Samantha
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Samantha

Love your site! My question is about the filter patches. Is there a way to do a DIY filter patch using medical tape or the painters tyvek material? I am wanting to make my own grow bags so they can be a specific height. What are your suggestions? Thank you!

Jacob
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Jacob

Does the freshness of the sawdust matter? I just sawed up a bunch of oak trees and want to try to grow lions mane in it.

Daniel Stewart
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Daniel Stewart

Hey Tony,
I mixed the bran and fuel pellets together before adding water then read your suggestion of adding the bran after the pellets softened…. I’m only doing 4 blocks as a tester so I’m going through with it, but was curious of your thoughts. Thanks!

Franco
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Franco

Hi Tony,

Thanks for the wonderful info on cultivation.

I have one particular question regarding Kings – pinning strategy.

I am currently growing on Poplar, bran, gypsum ratios respectively – 2.5kg bricks.

Some bags pin automatically and some only on the sides of the spawn bag. I am experimenting with a couple techniques like scraping and cold shocking – results still to come.

Any advice, I have seen those pics of Kings on your page!!

Kindest

Brendan
Guest
Brendan

I’m wondering whether there’s enough moisture in my mix now that I’ve added 1.4 L water to the 5 c of pellets. It broke up the pellets, but the moisture content seems well below “field capacity.” Should it feel fairly dry? Or should I add more water?

Thanks for all your great sharing, Tony!

Quinn
Guest
Quinn

Thanks for all the great info. I purchased some King Oyster and Shitake spawn from you a couple of months ago. It got placed in a corner of my basement and when I went to go do something with it, both were fruiting in the bags! Those are some vigorous strains you have there! Thanks. I was expecting the shitake to take longer and be more finicky. Anyway, I have done some grain to grain transfers to spawn bags and 1qt grain jars to keep the strains going and now plan on doing some wheat bran supplemented hardwood pellet fruiting… Read more »

Jeffrey Edmonds
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Jeffrey Edmonds

I carefully follow of this recipe and it is nowhere near field capacity!
I don’t understand why this is can you give me some advice this is my first grow on wood loving species. I’ve grown others

Do the sawdust blocks not require Field capacity?

Pete Tracy
Guest
Pete Tracy

Hi Tony, Great website… thanks for all of the info.
I’m new to this and excited to get started. I am curious about your opinion of using wheat germ oil in place of wheat bran.
–Pete

dale sarver
Guest

I grow oysters in buckets with straw. Is it possible to extend the production by adding a little sterile straw or rye to the mature bucket toward the end of fruiting?

Race Mullen
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Race Mullen

Why do you sterilize the mushroom blocks in a pressure cooker rather than in an oven?

Matthew Immergut
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Matthew Immergut

great site! thanks

Gerald Spittle
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Gerald Spittle

I have grown oyster mushrooms on hardwood stumps in the forest after logging using spawn in oil sprayed on with a garden sprayer. No need to be sterile. They fruited for several years. Same with shitake on oak logs using plugs, placed on the ground in shade. Why wouldn’t this work with unsterile wood chips in a burlap bag?

Craig
Guest
Craig

I have king oysters colonizing on millet and are doing quite well thus far. I plan on spawning to your pellet/bran ratio sterilized in my pc soon. My question is… have you ever used a monotub? Has anybody else? I have bags coming in the mail, but would rather use reusable materials.

Maria Whiteman
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Maria Whiteman

HI Tony, I’ve been making my substrate with a mixture of hardwood and softwood sawdust since the wood shops throw it all in one bag for me. Out of 10 growing bags two end up smelling off and I throw them out. It’s hard to find pure hardwood sawdust. Q: I don’t think I added enough wheat bran to my sawdust substrate and have already sterilized 7 bags, can I add the wheat bran in when I inoculate the bags with colonized spawning jars? The bags will be open and the colonized rye berries will be added to the growing… Read more »

Matthew Mackay
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Matthew Mackay

I don’t understand the extra filter. The bags I’ve ordered (and pictured above) have a filter built in. Is that filter alone not enough? I’m not sure I understand how you’re folding them or what that extra filter is made from etc. Any thoughts are welcome and appreciated, thanks!

James de Garis
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James de Garis

Do you reckon this could be altered to suit fruiting in a tub, rather then bags? Cause I would need so much more hardwood then what’s advised above. Maybe I could make a half and half mixture; this mix, mixed with something else?

Gabe G
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Gabe G

Hi Tony thanks so much for all of your help. I don’t have a flow hood but i do have a pressure canner and poly bags with a micron filter on them. If i were to inoculate straight into the sterilized substrate using LC, do i need to cover the hole up somehow afterwards? If so, what would you suggest? Thanks

nancy
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nancy

good morning, are there other options for wheat bran to add to the sawdust pellets for lions mane? I have spent coffee grounds, oatmeal, and rice on hand, not sure if any of that would work

Mohamed Kassem
Guest
Mohamed Kassem

hey Tony. I have bought hardwood pellets. however when i called the supplier, they said it is 75% hardwood and 25% softwood. will that work.