A Guide to Growing Mushrooms at Home

A friend recently asked me if I could help him grow mushrooms in his home - I don't think he knew exactly what he wanted so, in this article, I'm going to go over a few options for at-home growing depending on your budget and level of commitment. First, I will go over starting a small grow operation for the least amount of money possible, then I will provide a couple other options if either more money or time commitment is available.

For some context, mushroom farming involves two main parts: (1) the fruiting environment and (2) mycelium colonization (sterilization, inoculation, colonization) whereby the mushrooms are prepared for the fruiting process. The main variability in cost stems from how large and tightly controlled the fruiting environment is created to be and how far back you want to go in the mushroom growing process. For example, easy mode is this: getting a small Martha tent and buying a ready-to-fruit grow block. The most difficult version is the complete opposite: constructing a large temperature- and humidity- insulated grow room from scratch and breeding mushrooms on agar plates, then transferring to grain, then transferring to bulk substrate, the fruiting. How much money and time this takes is completely dependent on the level of depth the hobbiest/cultivator wants to go in.

Also keep in mind that mushroom cultivation can be done on a variety of mediums - sawdust, straw, spent coffee grounds, compost, dung. For indoor, home cultivation, I am going to focus exclusively on sawdust-based mediums as they are cleaner to work with in a home environment.

Shoe-string budget and Limited Commitment (budget: $150 - $200)

If you are on a shoe-string budget and want to get into mushroom growing for the least amount of money possible, I recommend getting a very small fruiting tent - called a Martha tent (aka mini-green house) - for $20 - $40 on amazon, which can be used to fruit the mushrooms. Also necessary is some sort of humidifier that has the ability to maintain a specific level of humidity (such as this AC infinity humidifier ~$70). A cheaper humidifier or one at home can be used if you just buy a humidistat which regulates humidity (such as this inkbird humidistat). Then, a small inline fan or even just computer fan is needed for fresh air exchange. So, a grow room environment can be set up for ~$150 if everything is bought piecemeal. These days various mushroom retailers such as North Spore provide pre-assembled kits for ease of use, so they can be bought as a package. However, I typically do not recommend buying these as they are much pricier than just buying individual components (maybe costs 3x as much as building yourself).

Then a ready-to-fruit block can just be purchased for ~$30 and placed inside the grow tent. Follow the instructions by setting humidity to ~90-95% to pin and reducing to 80 - 85% during fruiting and voila within 2 - 4 weeks you have fresh mushrooms. I would generally recommend buying from a company located in your geographic area as long shipping time may reduce quality of mushroom fruiting. The linked block is from North Spore based in Maine.

So, the total price of the above two steps is less than $200 dollars. Each time a new block is purchased for ~$30, it will convert to a few pounds of mushrooms across multiple flushes. Given that gourmet mushrooms can cost as much as $10 - $20/lb at markets, that is not a terrible ROI!

However, the downside of this approach is that it's almost TOO easy... You don't learn about any of the cultivation steps such as inoculating bulk substrate with grain spawn, sterilization, liquid cultures, agar, aseptic technique, etc. Let's move onto the next level.

Martha Tent + Pressure cooker (budget: $400 - $450):

In this case, the fruiting environment is the same as that of above - a Martha tent, humidifier, and computer fan are all that are used to create a fruiting environment. However, you go one level deeper by buying a pressure cooker. There are two main types of pressure cookers used by most amateur cultivators - the first are Presto pressure cookers and the second are All American pressure cookers. The Presto 23 quartz is typically much cheaper (currently at around ~$150 on amazon), so I recommend that one for someone just getting into mushroom farming. The volume is enough to sterilize two, ~6-lb bags of substrate in one run, which is enough to keep your Martha tent filled if you just run the sterilizer a few times a week.

The pressure cooker is necessary for sterilizing the bulk substrate at 15 PSI and making sure it is free from contaminants before the inoculation step. Then a still air box, can be purchased for the inoculations (maybe ~$30 - $40). Of course, a laminar flow hood is the golden standard, but those are a bit pricey and not entirely necessary for just grain spawn inoculations. There are techniques shown on YouTube where cultivators are able to achieve "good enough" sterilization using an insta-pot or just plain old cooking pot and steam but this increases the chance of bacterial infection and lengthens the necessary sterilization time. I generally recommend just getting a cheap Presto pressure cooker if you plan on getting involved in mushroom growing in any capacity.

At this point, you will not be buying ready-to-fruit mushroom blocks as in the first method. A bag of grain spawn - will be purchased for ~$30, then some sort of hardwood substrate and nutritional supplement will also need to be purchased. I recommend using 80% - 90% hardwood and either 10% - 20 % wheat or oat bran (preferably organic) for the highest quality mushrooms. However, note that other mediums like the famed Masters Mix (50% oak sawdust and 50%) are also commonly used and produce higher yields (but arguably lower quality mushrooms). Substrate can be purchased from many mushroom retailers or mushroom supply stores such as North Spore or Mushroom Media online. Note that special heat-resistant, autoclavable bags must be purchased for the sterilization process as temperature reach upwards of 250F at ~15 PSI. The amount of substrate used to make 10 ~5 lb bags is approximately 20 lbs (at 2 lbs of dry substrate per bag - mushroom bags are hydrated to be ~60% water weight), which would cost maybe ~$20).

All in all, this option costs around ~$250 more than the first option with the cost of the Presto cooker for ~$150 and the cost of substrate, unicorn bags, still air box, and maybe a few other things.

Large grow tent + pressure cooker (budget: $500 - $1000)

This option is the same as the one above, except that we switch the Martha tent for a larger grow tent, the computer fan with a powerful inline fan, and a small humidifier with a more powerful one to ensure enough humidity in the grow room. Tubing will also likely be necessary to intake/exhaust air through a nearby window.

If you are sure that you want to make an investment into mushroom farming, having a larger grow tent will enable you to provide more even humidification, control lighting, and maintain fresh air exchange more accurately than a small plastic martha tent. It will also enable you to fruit a larger number of mushrooms or experiment with multiple types of mushrooms at the same time. Grow tents can be purchased from vendors like AC infinity. This 4x2 tent (6 ft tall) can easily fit a single standard sized rack which could be used to simultaneously fruit up to 10 - 12, 5-lb blocks - maybe even more. This removes the limitation on fruiting space and allows you to experiment freely. Of course, slightly larger tents can also be purchased but at that point, you're entering the domain of small commercial operations which is probably overkill.

Additionally, while buying grain spawn and using it to inoculate sawdust sterilized in the Presto-pressure cooker is great, one drawback is that grain spawn bags typically come in 5 - 6lb bags. This is enough to inoculate up to 30, ~5-lb bulk substrate bags, which is much more than an amateur usually wants to do. One way to mitigate this is by buying liquid cultures, which are cheaper, which can they be expanded into grain spawn which can also be sterilized in the pressure cooker. This way, you can buy more liquid syringes and expand into grain yourself providing more variation in mushrooms grown without increasing the cost too much. However, this of course, involves a more knowledge, and know how - but that's the fun part!

Conclusion:

For a very new cultivator, buying a large grow room may be a large investment, so I would recommend just sticking to a Martha tent and getting the pressure cooker. The sterilization process is the bread and butter of what much of mushroom cultivation is so by bypassing that step, prospective amateurs are really missing out on a lot. Nevertheless, a Martha tent + fruiting block can always just be purchased for cheap to see how you like it.

Note that the above lists do not include many items typically associated with mushroom farming such as laminar flow hoods or some sort of HVAC control. I am assuming that the tent will be set up within the home and that the ambient temperature will remain around 65 - 75 degrees which is acceptable for many mushroom species.

Also note that the above listings are not 100% comprehensive and I may have forgotten to list a few little things that may be necessary here and there. I recommend watching one of the countless mushroom YouTubers online to learn more about beginner grow set ups.