Table of Contents
While most of our guides on mushroomgrowing.org are about growing mushrooms indoors in controlled environments, you can also grow mushrooms outside. Growing mushrooms outside means exposing your grow to more elements, but it can also let them flourish.
An addition to outdoor growing is that the sterilization process is not required, so you don’t need a pressure cooker or steamer to sterilize your substrate first.
Depending on the environment you live in, there can be different optimal setups. Read our guide here for the best steps and tips on how to grow mushrooms outside.
Overview: Growing Mushrooms Outdoors
Growing mushrooms outside is a hands-off process once you have the grow ready to go. You take more risks associated with exposure to elements such as sun and rain, as well as contamination. The benefit is that the setup is relatively easy and once it’s ready, you are almost completely hands-off until the end when it’s time to harvest.
Growing outdoors involves creating a ‘raised bed’ which will be a container that contains your growing medium and mushroom spawn/spores. This growing bed will be separate to the rest of your garden or yard, and will only contain your mushroom grow.
You will want to create the growing bed in a separate part of your outside area that’s ideal for mushroom growth. We will cover ideal conditions in this article. You will also need to consider the season of the area you live in, as growing mushrooms outdoors in the winter won’t work.
Ideal Conditions for Outdoor Growing
Seasons and Climate
The best conditions for growing outside are much like the artificial conditions you create indoors. You only need about 6-8 weeks to complete a single full grow cycle, so you don’t need a whole season.
For most people, growing during a spring/summer month is best, because the ideal temperature for most mushrooms will be around the 68F-80F range. Spring and summer months also have the ideal ranges of humidity. Remember, mushrooms naturally fruit in the springtime, so depending on your area, the spring/summer will probably be the best.
As for placing your grow in the right area, we recommend placing it where it will get more shade than direct sunlight during the day. This means near the outside of your house or building, so that shade is present.
It’s also beneficial to grow under the shade of trees or another outdoor structure such as a deck or shed. Avoid excessive sunlight, as this may dry out your growing medium too much.
Preparing Grow Materials
Raised Bed/Grow Bed
You will need a grow bed for your mushroom substrate only. This can be much like other gardening grow beds, or you can get creative with it. Here are some examples of grow beds you will want to use:
Wooden Raised Grow Bed
A raised grow bed such as the one pictured above will allow the water to drain out of the bottom, and it will effectively keep your mushroom grow separate to anything else in your yard such as grass or other plants. Wood is also a nice natural material to use.
Brick Raised Grow Bed
This type of grow bed made of brick will also work well for storing your mushroom growing substrate and spawn.
Plastic Raised Grow Bed
On a budget, you can also use a plastic tote to grow your mushrooms in. This will work fine just like the other methods, but keep in mind the limitations of plastic such as breaking, cracking, and drainage.
Overall, you will want to separate your mushroom grow from other things in your garden. This is very important to help prevent your mushrooms from having to fight through plant roots, other soils, contamination, etc. It allows your mushrooms to grow more easily and safely, with the ability to control the water content.
It’s also helpful to use a container that you can move around your outside space. If you find your first grow area to be too sunny, you want to be able to move it to a better spot.
Mushroom Growing Substrate
You will need to choose the proper substrate to fill your growing bed with. There are a couple of options that are the best for many types of commonly grown mushrooms. Here are the ideal options:
- Hardwood Chips/Sawdust Mix
- Wheat Straw
These are 2 materials that will serve you well when growing mushrooms outside. They will absorb water without holding too much, and they also serve as very nutritional options for your mushrooms as they colonize and grow.
You can also research more specific substrates for the type of mushrooms you’d like to grow. For basic edible mushrooms such as Oyster mushrooms, the above options will serve you best.
A common concern with growing outdoors is contamination. Unfortunately, when it comes to outdoor growing, you can’t avoid contamination entirely. You don’t need to pressure-sterilize or steam-sterilize your substrate for outdoor growing, as potential contamination is already abundant.
Read more about mushroom growing substrates on our post here.
Mushroom Spore Selection
As usual, for growing mushrooms, you will need to select mushroom spores which you will add to your mushroom. Our recommendation is to select a mushroom that will grow well given the conditions we provided above, spring/summertime in an average climate. You will also want to choose a mushroom spore that feeds well off of the recommended substrates.
The best options given these factors are king oyster mushrooms, blue oyster mushrooms, or portobello mushrooms.
Find oyster mushroom spore syringes on Amazon here.
Buy a spore syringe from an online vendor that contains spores from one of these types of mushrooms, this is what you will use to add spores to your grow setup:
Note: You can also buy mushroom spawn with spores already added. This is mushroom substrate with mushroom spores already mixed into it. This can work well for an outdoor grow, and you’ll mix this into the rest of your substrate when it’s ready.
We have plenty of guides on special types of mushrooms on our blog here.
Setting Up the Outside Mushroom Grow
Now that you have all of your materials, it’s time to prepare your growing environment.
Place your grow bed in your ideal spot outside according to the directions provided above. As mentioned, this will be a in a mostly-shaded spot outside, where occasional sunlight may strike. Keep it away from specific water drainage areas, also.
Fill your bed with your mushroom substrate, about halfway to the top, leaving room for another layer. Depending on how big or deep your bed is, you will need a few cubic feet of substrate whether it’s wheat straw or sawdust/woodchips.
Add water to your substrate. You don’t want to completely douse your substrate, but get it damp/moist. Mix the substrate around in the water to spread it evenly.
Add your spores. Take your spore syringe, and add about 10-20 drops from the syringe to the grow evenly throughout.
Add another layer of your substrate, now filling the container almost to the top. Add a little bit more water to this top later, without adding more water.
Your mushroom growing bed is now complete!
Outside Mushroom Grow Process
Overview
Now that your mushroom growing bed is properly made and you’ve added your mushroom spores, you’re ready to observe and maintain the mushroom growing process.
As mentioned above, this process will now take a couple of weeks- a few weeks before you see any results. The process can take a highly variable amount of time depending on temperatures, humidity levels, and other factors.
The mushroom spores will attach to the nutritious substrate and begin to form mycelium. Mycelium is a white, webby material that the mushrooms will eventually fruit from. You may or may not see the mycelium on the grow bed, as it usually will take place underneath the surface, much like in the natural world.
Avoid mixing or otherwise touching the mushroom substrate during these critical days of colonization. The mushroom substrate should not be heavily disturbed as the mycelium attempts to grow.
Lastly, keep in mind that your mushrooms may never grow with an outside grow method. Contamination outside is a very possible issue, and this will completely stop your grow. Unfortunately, you have to simply roll the dice on this and take a chance.
Watering
The most important things to remember during this period is to keep an eye on the water level of your mushroom grow:
Mushrooms naturally grow during springtime when the ground soil is wet from frequent rains. This is the type of condition you want to keep with your mushrooms. Water the bed regularly, but don’t drown it. If your area is in a drought period from rain, then you will want to water more frequently.
Fruiting
If all has gone well, and your mushrooms did not encounter any contamination that stopped the mycelium from growing, you will see mushrooms begin to fruit out of the bed!
Don’t get too excited just yet- let the mushrooms grow for a day or two and keep a close eye on their growth.
In general, the ideal time to harvest mushrooms is right before the caps open to release more spores. If you go too early, the mushrooms won’t be as nutritious or enjoyable. If you wait too long, the spores will spread and can ruin the mushrooms also.
Harvesting fruited mushrooms consists of cutting them from the base or pulling and twisting them gently out of the bed.
Once you’ve harvested the mushrooms, either dry them in a food dehydrator for long term storage or immediately put them in the fridge! Fresh mushrooms won’t last very long, try to consume them before a week passes.
Conclusion
Congratulations – You’ve completed the guide on how to grow mushrooms outside. This process can be fun and more preferable to experienced growers than growing inside. It requires a bit less work, but you also run the risk of contamination without much defense against it.
A big plus to the outdoor grow method is not requiring pasteurization/sterilization of the grow medium, which can be tedious to new growers.
Overall, growing mushrooms outside is a simple and fun task that only takes about 6-8 weeks to complete. Mushrooms are a great addition to any yard or garden. Good luck!
