Note: This is a guide about growing edible cooking mushrooms. While some of the advice might apply to other types of mushrooms, this shouldn’t be considered advice for growing recreational mushrooms.
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Mushrooms are a controversial food.
Personally, I love them. But growing up, I only ate mushrooms in restaurants or relatives’ homes because they were all but banned in our kitchen!
As controversial as they are in the kitchen, mushrooms are arguably more controversial in the garden. Because mushrooms have unique growing requirements, it can be intimidating to start growing them at home.
If you’re a mushroom lover looking to expand your garden, the good news is that growing mushrooms is easier than you think!
An easy way to start is growing mushrooms in grow bags.
Can Mushrooms Grow in a Grow Bag?
Mushrooms can grow just about anywhere, as long as they have the right growing medium and environmental conditions.
Grow bags are a good place for mushrooms, because:
- Bags are moveable, in case you need a better location
- Water doesn’t pool up in grow bags
- Grow bags are flexible, allowing you to use different growing mediums
- Bags surround the mushroom and growing medium, keeping in extra moisture
- Bags protect mushrooms from wind and sunlight exposure
Mushrooms aren’t too picky about what they’re grown in. The main thing they care about is the growing conditions, not necessarily where they’re planted.
With mushrooms, growing mediums are referred to as the substrate. I’m going to use the terms substrate and growing medium interchangeably since they refer to the same thing.
Mushrooms need a lot of nutrients to grow well. You can use a soil mixture or a solid, porous organic material. Depending on the type of mushrooms you’re growing and your setup, you have a lot of choices.
If you’re using soil, you need to mix in a lot of organic materials, such as compost or wood chips. There should be an equal amount of soil and compost. Ideally, the compost should have chunks of organic material, such as wood chips, to allow the mushrooms to grow well for a long time.
Soil isn’t necessary for growing mushrooms. You can use logs, wood chips, sawdust, solid compost, or any mix of these to grow them instead.
Mushroom Variety Requirements
Before you settle on a growing medium, make a decision about what kind of mushrooms you want to grow. Depending on the variety, they might have different preferences for growing mediums.
Just like other plants, many mushroom species thrive in specific growing conditions.
These are some of the most commonly grown edible mushrooms and the growing mediums they prefer:
White button mushrooms (AKA white champignon)
Preferred substrate: mixture of composted manure and straw.
Cremini mushrooms (AKA Portabella)
Preferred substrate: compost mixed with straw.
Preferred substrate: sawdust, compost, or straw.
Preferred substrate: fresh-cut logs, especially thick logs made from hardwoods like oak or maple. Avoid softwoods like apple, ash, pine, or spruce.
Preferred substrate: straw, corrugated cardboard, corn cobs, wood chips.
Porcini mushrooms (AKA bolete)
Preferred substrate: hay, corn cobs, sawdust, compost, or a mixture of these things.
Preferred substrate: mixture of soil, compost, and sawdust or wood chips. May also grow well on logs in soil.
Because of how mushrooms prefer to grow, the mushrooms you want to plant may have to compete against other fungi or mold in the growing medium. To help prevent this, you should sterilize your growing medium before you plant anything in it.
Depending on the type of growing medium you’re using, the sterilization method will vary. Pasteurization is a common method for sterilizing mushroom substrate because it kills existing bacteria, fungi, and mold without damaging the material itself.
Make sure to wash any reused grow bags to sterilize them before adding your substrate.
Once your substrate is prepared, you have two main options for planting mushrooms. Either plant the spores or cultivate an existing mushroom spawn.
Before we get into how to plant each type, it’s helpful to understand the difference.
Spores act like mushroom seeds, but mushrooms don’t grow directly from the spores. Instead, spores grow into mycelium, which will produce mushrooms as fruit once it has matured enough. Mycelium grows on the substrate, breaking down the organic material for nutrients.
Once mushrooms mature, they release additional spores that can repopulate the mycelium.
Spawn is what you call substrate that already has some mycelium growing on it. This will grow into maturity faster, resulting in faster fruiting. It’s similar to propagating a new plant from a mature plant cutting.
You can get spores for common mushrooms either online or at some local nurseries.
Plant mushroom spores by spreading them over your substrate. Make sure you have sterilized your substrate ahead of time and wash your hands before handling both the spores and the substrate.
You can also inject spores into the substrate by using a spore syringe. This method helps if you’re growing mushrooms in a closed container like a jar, but it can also be used with a grow bag.
After planting spores, keep your substrate moist but not wet. Since mushrooms don’t like light, you can even cover the substrate with a damp towel to track in more moisture.
You may also be able to use the grow bag itself, spraying it to keep the bag moist throughout the day and folding it over the top to lock in moisture.
Keep the substrate warm while you wait for the spores to grow mycelium. The goal is to create ideal conditions to grow mycelium. The more mycelium you have and the healthier it is, the better your harvest will be later on.
Planting spawn is simpler than planting spores. Since spawn is existing mycelium growth on the substrate, you can mix it in with your new substrate to spread it around further.
Spawn will grow into more mycelium, eventually maturing and fruiting.
Fruiting will be faster when you plant spawn because you’re skipping the step of growing new mycelium. Mushrooms that grow from spawn will release spores when they mature, continuing the cycle of mycelium.
Spawn is generally an easier option for beginners. There are fewer opportunities for failure with spawn since it is less likely to become contaminated while growing and won’t have to compete with other fungi or mold.
Choosing a Location
So, your mushrooms are all planted and ready to grow?
Now you need to put your grow bag somewhere that your mushrooms will love.
Mushrooms do best indoors where you can better control the environment. Put your grow bag somewhere away from the light. Feel free to be creative and frugal!
Mushrooms will do well as long as they are not exposed to sun, strong airflow, or huge temperature fluctuations. Put the bag under the sink, in a closet, on a shelf in the garage, or just in the corner of a room on the floor somewhere.
Don’t stress too much about the location. Since you’re using a grow bag, you can always move it somewhere else if you run into issues with the spot you chose first.
Maintaining Ideal Conditions
What do mushrooms need in order to grow?
They are a little picky, but if you get things into the right range, you’ll be fine.
These are the main things to focus on for growing mushrooms:
Mushrooms don’t like it too hot or too cold.
Keep your mushrooms in an area that doesn’t experience extreme temperature swings in either direction. This is why growing them indoors is recommended, because your indoor spaces are more likely to be temperature controlled than outdoor spaces.
The ideal temperature range for most mushrooms is between 55-65° F (around 13-18° C).
Mushrooms love moisture, but they don’t love standing water.
You want to keep the growing medium moist without allowing water to pool up. Watering with a spray bottle can help to add moisture without overwhelming it.
If dryness is a problem, you can help to trap moisture in the grow bag by putting a plastic bag as a liner inside before adding your growing medium, or over the top to trap in more moisture.
Mushrooms don’t mix well with sunlight.
Because they are fungi, they actually don’t need any direct sunlight to grow. This gives you a lot more options for where to grow your mushrooms because you can tuck them away into a space that’s not useful for other plants.
Harvesting & Replanting
When your mushrooms are growing well, it’s time for the exciting part!
Most mushrooms fruit for a few weeks at a time.
Once your mushrooms are growing well, you can harvest them as they mature. Continuous harvesting allows the mycelium to keep fruiting as long as possible.
Check your specific mushroom variety to know exactly when to harvest.
When you harvest, use a sharp knife or a pair of scissors to cut the mushroom stem close to the bottom.
You can also pick the mushrooms by hand, but this can damage the mycelium and may disrupt the growth of other mushrooms around the one you’re harvesting. Leaving the mycelium intact can also lead to further fruiting in the same spot or beside the older stems.
With most mushrooms, you can get regrowth in the same grow bag if you wait to harvest until after the spores have been released.
Once the spores are released, they will repopulate the mycelium and start a new growth cycle. If you harvest too soon and the spores have not been released, there will be no way for the mycelium to continue growing, spreading, and re-fruiting.
The easiest way to tell whether a mushroom has released spores or not is to look at the tops. Most mushrooms release spores from below their hoods. When the mushroom top curls upward, it opens and releases the spores.
Check the specifics of the mushroom species you’re growing to get more insight into when the spores are released.
Growing mushrooms in a grow bag is a great way to start adding a more diverse selection of plants to your garden.
If you set up the crop well and keep an eye on the moisture, you’re likely to get a healthy harvest for weeks once the mushrooms begin to fruit.
Don’t be afraid to give it a try yourself!
Read next: What Can You Grow in a Grow Bag?