Beginners Guide to Growing Oyster Mushrooms At Home


Posted by John Minton | Posted in Fungi, How to's | Last Updated December 4, 2016


Growing mushrooms is a lot easier than you may think. It’s cheap, it’s fun, and you get delicious, organic, high-quality produce out of it! When I first started looking into growing my own mushrooms I felt overwhelmed because the information appeared very technical, and while the instructions I received made sense, I wasn’t sure how to actually do it and I doubted my own capabilities and understanding. I got in contact with a local mushroom hobbyist and connoisseur, Milo Olson, who explained how it all works. I got hands on experience seeing how he grows his mushrooms and now I am confident that I can too. On top of learning how to grow my own mushrooms at home, Milo took me on my first wild mushroom hunt! During our adventure I had the privilege of picking his brain about all of my mushroom related questions. Actually, I now have an excellent grasp on how to cultivate my own mushrooms at home. The process is straight-forward and you can harvest a substantial crop from even a small area.

Understanding Mushroom Growth

Mycelium growing on a logMushrooms are Fungus. Adult mushrooms (mushroom fruits, or fruit body’s) drop tiny dust-particle sized spores once they reach a mature age and before they die. Those spores are like seeds, they will grow into what is basically the root structure of the mushroom, called mycelium. A mycelium typically looks like a white mold, or a fuzzy white intricate network of tiny roots with no plant top attached. There are 2 kinds of mycelium – the first is mycelium that grows from a spore, known as monokaryotic – and it will not produce mushrooms. It needs to come into contact with another monokaryotic mycelium from the same or similar mushroom species. Once these two monokaryotic mycelium touch they will begin to grow the other type of mycelium that can produce mushroom fruits, known as dikaryotic mycelium (also called a secondary strain). A dikaryotic mycelium is a genetic offspring of the first two. This sounds complicated to apply to growing mushrooms, but it’s actually pretty easy. When you buy certified mushroom spores, they will grow into each other and produce the dikaryotic mycelium needed to grow mushrooms – without any extra effort on your part. Advanced mushroom growers will grow mycelium in petri dishes and look for certain qualities in the mycelium that they want, and will cultivate a mycelium that will fruit more, larger and healthier mushroom fruits. More details on this later.

Making Spore PrintsThere are many different kinds of mushrooms and a number of substrates that each can or can not grow on. Mycelium may take 2-3 weeks to colonize or it could take many months. Oyster Mushrooms grown in hay can colonize in a month and and fruit 3 times give or take. If you are growing Shiitake Mushrooms on logs, they can take many months to colonize but they can fruit regularly for up to 10 years. So colonization, incubation, and fruiting can vary greatly depending on the type of substrate and mushroom you choose to cultivate. An adult mushroom can be harvested to make a spore print to save for future generations, or a sliver of mycelium can be  grown in a sterile container and kept in a refrigerator for years. So once you start a mushroom culture, if you take care of it, you will never have to buy spores again!  If you normally buy mushrooms then this will certainly save you money in the long run after initial costs.


Bag sprouting Oyster MushroomsWe are planning to grow Oyster mushrooms in 1 or 2 large bags. You will inoculate the bags with spores, let them fully colonize, and then fruit them. Mushrooms require a specific environment so we will construct a simple box to grow in. The entire process can take around 3-5 weeks to reach the first fruiting. Each bag should fruit 3 times or so about 2 weeks apart.


  1. Gather materials
  2. Mix and Sterilize substrate
  3. Inoculate and Colonization substrate
  4. Create our mushroom grow box
  5. Fruiting
  6. Harvest
  7. Material Resources
  8. Online Resources

Gathering Materials

You will probably need:

  1. Scotch Tape or Duck Tape
  2. A sheet of plastic, or a couple large white/semi see through garbage bags
  3. Something you can drape the plastic sheets over, such as a laundry basket, where you will fruit your mushrooms.
  4. A box of large plastic ziplock bags, anywhere around the 1 gallon size is fine.
  5. Water
  6. A large tote
  7. 1/2 cup of wood ashes, just take a scoop from a recently used fire place
  8. Wheat Hay / Straw. A flake of straw would be enough for at least 4 bags.
  9. Oyster mushroom grain spawn
  10. A dark cool place for the colonization of your mushroom bags, such as a closet

Tools that you will probably need to use:

  1. A sharp knife
  2. Sharp Scissors

Mix and Sterilize Substrate

Hay soaking in waterFirst we need to prepare your straw, it will be the substrate your will grow your mushrooms in. Fill the tote with enough water to submerse the flake of hay, then add the 1/2 cup of wood ash and mix it into the water. Put your hay into the water. Feel free to place a sheet of plastic and a rock or something heavy to keep it submersed. Let the hay soak in the water for the rest of the day, at least 16 hours. This process won’t kill off everything living in the hay but it does work to pasteurize the hay in a sense as it kills off some of the microbiology that would otherwise grow. It helps you keep the hay clean and the water it soaks up is needed when you grow your mushrooms.

You are now ready to inoculate your substrate as you fill your bags. Oyster mushrooms are a good mushroom to start with because they grow better in non-perfectly-sterile conditions. When there is a small amount of other biology in your mushroom bag, the Oysters mycelium will over-grow them without much trouble. This is why soaking the hay in water mixed with wood ash works well. This controlled competition gives you better mushrooms, and sterilization – which can be time consuming and even costly – can be mostly avoided.

Inoculate and Colonize Substrate

Inoculated Bags of StrawAfter your hay is ready, get your 1 gallon zip lock bags and your grain spawn ready. Grab a large handful of the wet hay and stuff it into your bag, then add about 1/4 cup of grain spawn on top. Repeat this process until the bag is full. Pack it down every few handfuls or so. The idea is that the grain spawn will start to grow in layers in your hay, and you don’t want a whole lot of space in there as the hay is kind of springy and also hallow. Without packing the hay so tight that the mycelium can’t move through it, you want to get as much hay in your bags as possible. After the bags are filled up and the top of the bag is closed, you are going to but some holes across the front of the bag. Use a knife or scissors to cut “x” shaped cuts about 3/4 square inch in size. This is where the mushrooms will grow out from. If you cut more holes in the bags, you may get more mushrooms to fruit but they will be smaller. If you poke less holes, you may get less mushrooms but they will be larger. Depending on the size of your bags you may need to cut more or less holes to get the size of mushrooms you want. It’s something to experiment with. For the next 4 weeks you will let your bags sit in your closet or other cool dark place until they are fully colonized. It’s OK if mushrooms are in colder temperatures, they will just take longer to grow – but high heat, around 80°, will kill them or prevent them from fruiting. During these first 4 weeks you maybe see grains from the hay or or your grain spawn sprout, and you should see the white mycelium grow throughout the bags. you want to let it grow until the bag is pretty much solid white. Once they are solid white you will want to move them to your mushroom box (which you will make in the next step).

Create our Mushroom Grow Box

Home made Mushroom BoxWhen your mushrooms are in the colonizing stage they will need to be in a cool, dark place such as a closet. When it comes time to fruit your mushrooms they will need a little bit of filtered light, high humidity and oxygen in order to grow. So we need to construct a fruiting “box” out of whatever you have available to you. If can be as simple as throwing a white or semi-see-through trash bag over an upside down laundry basket (secure any loose plastic around the edges of the laundry basket). It doesn’t need to be fancy, you have the opportunity to recycle junk you may have laying around the house. Other ideas, you could use an old fish tank, a tote, or even modify an old junk coffee table or old chair. Be creative – you just need an area to grow your mushrooms that can keep humidity levels high enough  but still let some filtered light in. If you need plastic, you can cut a garbage bags along the seam of 2 sides so you have a large sheet. Use tape, staples or glue to attach plastic to your structure.


Fruiting Oyster MushroomsAfter colonization when your mushrooms are ready to start their fruiting process, you need to take your mushroom box out and place it where it can see light. It doesn’t take very much light to stimulate the mushrooms. If it’s summer time, try not to place it in direct sunlight as it can heat up too much.  Otherwise, normal room temperature is fine. To keep the humidity high it is easiest to buy a humidifier and put it in your mushroom box. If you don’t want to spend the money you can place a small tray or tupperware with water inside your mushroom box (add some rocks to help displace the surface area of the water). The higher the relative humidity inside your mushroom box the better. You should aim for 90% relative humidity. If possible, add more than one tray with water to help keep the humidity up. It is OK to set the bags on the water tray(s) as long as the water doesn’t get into the bags or touch the fruiting mushrooms and the bags don’t prevent the water from creating humidity. If you can, 3 times a day lift of the mushroom box and let the air out. The mushrooms will off gas CO2, but they need oxygen to grow. If you can’t do it 3 times a day, do it as often as you can. It is worth it to invest into a temperature and humidity sensor to place in your mushroom box.


Mushrooms in Mushroom boxYou can harvest mushrooms any time during the fruiting process – any time your mushrooms reach a mature size. Simply pick them off of the bag, being careful not to jar or impact the bag itself which can prevent the bag from fruiting in the future for a time. When a bag grows mushrooms we call it a flush. Most of the time you can get 3 flushes out of a single bag. You can eat your mushrooms immediately, refrigerate them for later or dry them. The mushroom fruit bodies that do not grow to normal sizes are called aborts and can be picked off as well, so other mushrooms can grow in future flushes. In very rare occasions, a bag that did not fully colonize properly may grow other mushrooms that came in with your substrate. Be sure that the mushrooms you harvest look like the ones you are trying to grow. They should all be the same shape, color and smell. When harvesting you can also plan and prepare to collect spores from your mushrooms to save for later. The mushrooms will drop spores even when they are young, but they will drop more towards the end of their lifespan. After harvest gently cut the stem off one or more of your Oyster mushroom and place it on a clean piece of aluminum foil or white paper. Place your mushroom on a table and place some sort of container over top to keep other spores and air from reaching your spore print. The gills of the mushroom should drop spores over the next 12 hours or more. Come back and check by lifting the mushroom cap, you should see the spores on your paper or aluminum. Many Oyster mushrooms have lilac purple colored spores. Cut the spore print out and place it in an air tight ziplock or similar bag and store in a refrigerator for future use.

Cooking Oyster Mushrooms

The best part about growing mushrooms is getting to eat them! Here is a small list of how I like to prepare them.

Sautéing Oyster Mushrooms with Veggies

Cooking Oyster Mushrooms


Oysters will absorb water while they are growing or being cooked in a soup or frying pan, so they are usually not used for soups unless perhaps they are dehydrated first. Heat up a frying pan. Don’t add any extra oil or water yet. Let the Oysters heat up, they will release their water from their flesh. This water if full of flavor, so when you see it, it’s an ideal time to throw in some onions, garlic or other veggies. After it appears they are no longer releasing water, add some oil or butter and Sautee the mushrooms and veggies until crispy or to your preference. This is my favorite way to eat my Oyster mushrooms!

Cooking on Grill or BBQ

Oysters are sometimes used as meat substitutes! Throw the whole mushroom onto a grill, painted with oil and herbs or breaded, cook it like it’s a piece of meat!

Misc Cooking Ideas

Cut up and top a pizza, cook with an omelet, make a gravy and serve with rice, use as a meat substitute and serve in burgers! The possibilities are endless!

Material Resources

Pearl & Chocolate Oyster MushroomsI have hand selected the products at the end of this post. Many of them should be useful if you plan to follow this guide. A little bonus, purchasing them helps support Garden Of Tomorrow! Please consider making purchases from Amazon after following one of the product links below to help the site out!

Online Resources

If you want to further learn about growing mushrooms, there are many excellent online resources: Mycological Society of San Francisco is a very excellent resource! They are basically the authority on anything mushrooms! is by far one of the most recognizable online communities. Google a question and their forums usually come up with a discussion on it.