Growing oyster mushrooms in containers outside is a great way to incorporate mushrooms into your space and pretty easy to set up and maintain. You'll need just a few things for the process: a container, straw or other agricultural waste, mushroom spawn, a water source, and tub or pot to soak the straw in.
First some considerations in choosing a container: The container you choose should have some airflow so the fungi can breathe and excess water can drain off. If you’re using a plastic bucket, drill some holes into it. Most folks create a diamond pattern every few inches, ¼” diameter holes work well. Remember to put a few in the bottom, too, so excess moisture can drain out. We've used laundry hampers and plastic plant pots with great success. A friend even grew mushrooms out of a birdcage! So feel free to get creative in your choice.
Then, you'll want to source your material to grow on. Oysters love agricultural waste- rye or wheat straw is often easily accessible in our region and what we've most often used. But feel free to use whatever resources are at your disposal. We found a bag of pre-chopped straw at our local garden center. The smaller particle size is ideal for mushroom growth- pieces 1-3" in size. If you can’t find a material like this, there are lots of DIY options for chopping straw. (like putting it in a garbage can and running a weed whacker through it) It’s also totally okay to skip this step. Just make sure to compress the straw a bit more to get the pieces tighter together. This helps the mycelium grow through the substrate a little better.
Next, you'll want to hydrate your straw. We let ours soak in a bucket for an hour with a brick on top, then let it drain until the straw only drips a drop or two when squeezed. Measuring hydration like this is referred to as checking “field capacity” and can apply to other substrates as well. If your substrate is too wet, it can create anaerobic conditions, leading to contamination. Too dry, and the mycelium won’t be able to grow. Finding the balance is simple with a squeeze test.
Once properly hydrated, pack your straw into some containers, sprinkling spawn between each layer. Finish it off with a top layer of spawn. Alternatively, you can mix your straw and spawn on a tarp and pack them all into your container at once.
If your containers will be outside, you can water them as you would plants in your garden, taking care to not let them dry out or become soggy. Depending on how much spawn you used, the temperature, and size of container you may start to see mushrooms in 1-3 months!