By far the easiest mushroom to grow at home is the oyster mushroom. It’s popular as a kit, kits are ready to fruit once holes are cut into the bag and placed in a humid location without much airflow, that would otherwise dry it out. Small kits are highly commercialized, and available at walmart, home depot and other similar stores.
Online bigger kits are available and often more productive: We offer our own ready to fruit kits on our shop.
However, if you’d like to grow oyster mushrooms in a more economical way, on a sizable scale, kits can be too expensive unless you have a good cheap bulk source of ready to fruit blocks.
A good option to grow at home is to use wheat straw; it can be used to grow large quantities of oyster mushrooms without any additional supplementation and without any heat pasteurization or clean work. Heat pasteurization can often be difficult to manage and dangerous, and clean room work can be an expensive barrier of entry to new mushroom growers.
Materials Needed To Grow Oyster Mushrooms on Straw
1. Wheat Straw – ideally shredded. Wheat straw is often smaller and easier to shred and manipulate than barley or other straws, but these will work as well. Pre-shredded wheat straw is often available at Tractor Supply, but it is much more expensive than baled straw.
2. Hi Yield Hydrated Lime – this is a pasteurizing agent and is often available at garden supply stores. Other products also called lime will not work if they are not low magnesium calcium hydroxide.
3. Water – This, combined with the hydrated lime, will hydrate and pasteurize the straw, getting it ready to be inoculated with oyster mushroom spawn, or a kit (either before or after the kit has fruited; so long as it looks healthy)
4. Soaking & Draining Container – this is to let the straw hydrate and pasteurize in the hydrated lime solution. as welll as let it drain once fully hydrated which takes approximately 24 hours to soak, and an hour or two to fully drain.
5. Bag or Container for Colonization – This could be 5 gallon buckets with holes drilled in them, large durable plastic bags, or anything else that can hold a few pounds of hydrated straw.
Steps to Grow Oyster Mushrooms on Straw
1. Get shredded wheat straw – this can either be purchased at places like tractor supply or you can buy bales of straw from a farmer and shred them yourself. This can be extremely messy, and isn’t absolutely needed, but shredding the straw significantly increases yields and makes for a better more compact substrate that is less likely to have problems and colonizes faster.
2. Add and compress the shredded wheat straw into your soaking container. Make sure your container has a means to drain or is small enough that you can easily pour off the water without the straw going with it. You will want to let the straw drain until no more water comes off of it, so make sure it has a sieve or a good drain on the bottom. You will also want something that can hold down the straw so it is fully submerged during the soak.
3. Dissolve hydrated lime in water. Add enough of this solution to completely submerge the straw, again, having something to weight down the straw is a good idea to ensure all of the straw gets properly hydrated and pasteurized. Exact amounts of lime is difficult to provide but 330 grams per 50 gallons of water is the generally recommended. More is often better as excess will be poured off with the solution. That said, as long as the solution is strongly basic and remains strongly basic throughout the soaking process it will work well.
When we do it, we use a 55 gallon drum, and use a pump at the bottom of the barrel to recirculate the water and lime mixture.
There is a circular hose at the top with many holes drilled in it to help the lime mix properly by circulating it from top to bottom, and distributing it over the top.
It is better to mix the lime with the water before hand to ensure even mixing unless you have a setup similar to this. The pump also doubles as a means to drain the solution from the 55 gallon drum so that it can be manipulated more easily.
Once the straw has soaked for ~24 hours, and has fully drained, we pour the shredded straw on a clean tarp and add spawn. We’ve used as little as one spent 5 lbs straw oyster log from previous cold pasteurization or a single 3 lbs bag of colonized grain spawn with great success, but we normally use a lot more colonized grain spawn as we are a company primarily focused on grain spawn, so we have a lot of it in excess. Grain spawn is nutritious and adding more will increase yields and decrease contamination rates and lead to faster colonization and fruiting of the substrate.
4. Mix prepared straw with oyster spawn – oyster spawn can be purchased and used, or even smaller grow kits can be used to inoculate straw by breaking them up. A grow kit that has already produced fruits but still looks healthy is a great option so long as it is free of obvious contamination such as other unwanted molds. The better the spawn is broken into small pieces and evenly distributed through out the straw, the faster it will colonize. More grain spawn is better as it will provide faster colonization and additional nutrients but we’ve had great success with 4% grain spawn by weight.
5. Place straw and spawn mix into the container which it will fruit from. This could be anything from large ziplock bags, trash bags, 5 gallon buckets, or even very large polytube bags that are 5+ feet tall and 1ft in diameter.
Here are pictures of two vastly different sizes of oyster straw bags.
6. Ensure container has holes for fruiting, approximately every 5 inches over it’s surface. This is important or the oyster mushroom to properly colonize, and for the mushrooms to grow, as they will grow out of these holes. Hole size can vary a good amount ranging from a dime sized hole up to a cut the entire length of the bag. The colonizing substrate needs to breath in order to colonize without contamination. A filter patch is often less ideal than cutting holes. The holes provide air exchange as well as a location for the mushrooms to grow out of the substrate for harvesting.
This is a polytube bag approximately 2.5 feet tall and 1 foot in diameter. Various holes were cut to let the oyster mushroom breath as it colonizes. Oyster mushrooms will grow out of these holes once it has consolidated.
Shredded Straw VS Regular Unshredded Straw
One might be tempted to skip using shredded straw and instead opt to use straw straight from the bale in hopes of reducing labor, machinery to shred the straw and to avoid the messy dusty nightmare that is inexorably linked to shredding straw.
But, shredded straw has significant benefits both on yield and density of substrate which translates to being able to grow more mushrooms in the same amount of space.
This study: Simplified and Lower Cost Methods for Culinary-Medicinal Mushrooms Cultivation shows that shredded straw can have 4 times the yield as unshredded straw; going from approximately 40% to 170% biological efficiency. One 50 lbs bale of straw can yield 85 lbs of fresh oyster mushrooms if it is shredded, but may only yield 20 lbs if it regular not shredded straw.
Images of Oysters Grown on Lime Pasteurized Straw
Have questions about this process? Just ask!
If you’d like to grow oyster or other mushrooms and need any help or further guidance, please reach out to us.
We would be happy to walk you through anything from a small personal grow using straw or help you hone in a larger commercial project that uses master mix or other supplemented sawdust.
You can get direct help by texting 435-237-2998 or emailing Cameron@spawnmagic.com