Substrate Types for Growing Mushrooms
What is Substrate?
Substrate is the material mushrooms grow in, whether in garden beds or containers. It supplies the nutrients and moisture mushrooms need and gives the mycelium something to grow through.
How to Choose the Right Substrate for Growing Mushrooms?
Each kind of mushroom has its own substrate preferences, so for good yields and quality, match the substrate to the mushroom. Use the chart below to pair your mushroom strain with a suitable growing method and substrate.
| Substrate Suitability for Growing Mushrooms | ||||
|---|---|---|---|---|
| Mushroom Strain | Growing Method | Compatible Substrate | ||
| Almond agaricus | Beds or containers | Manure or nitrogen-rich compost | ||
| Lion's Mane | Logs, containers | Logs, straw, hardwood sawdust or wood chips | ||
| Oyster | Logs, containers or beds | Hardwood sawdust, straw, wood chips or agricultural byproducts* | ||
| Wine Cap | Beds or containers | Hardwood (or mostly hardwood) wood chips | ||
| Chart data courtesy of North Spore. *Agricultural byproducts include manure, coffee grounds, grass clippings, leaves, straw, corn cobs, hardwood sawdust, banana leaves, cottonseed hulls, newspaper and cardboard. |
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How to Prepare Substrate for Growing in Containers
If you're growing mushrooms in containers, indoors or out, prepare the substrate before inoculating. This lowers the chance of contamination by competing fungi or bacteria while keeping helpful microbes.
Start with fresh substrate, which is less likely to be contaminated than material that has sat around. You can also treat it to knock back unwanted fungi and bacteria. Two common treatments:
- Cold-water lime soak: Mix about 6 grams of hydrated lime per gallon of water, adjusting as needed for your water's pH, and aim for a pH of about 12.5. Soak the substrate at least 12 hours, then let it drain to the right moisture before inoculating: damp, but not dripping lots of water when squeezed.
- Hot water: soak the substrate in water held between 145°F and 185°F for several hours to kill harmful organisms while sparing beneficial ones. Add boiling water as needed to keep the temperature up. Let the substrate cool to room temperature before inoculating, since spawn added to hot substrate will probably die.
How to Inoculate Substrate
Container Inoculation
Mushrooms can be grown in containers indoors or outside. Depending on the strain, they'll fruit from the sides or the top of the container.
- For side-fruiting strains, use a container with openings in the sides, such as a milk crate or bulb crate, or drill holes. Holes about ½" across let mushrooms emerge while limiting moisture loss during colonization. Top-fruiting strains need no holes beyond the container's open top.
- Sterilize the container to lower the risk of contamination.
- Wet the substrate. Aim for about 50% moisture, meaning the substrate weighs roughly twice its dry weight.
- Break up and mix in the spawn at ½ to 1 bag per 5 gallons of substrate. More spawn means faster, more dependable colonization and is a good idea for beginners.
- Fill the container with the spawn-substrate mix, either blending thoroughly or alternating layers of substrate and spawn.
Bed Inoculation
Some strains do well in outdoor beds, between garden rows, or anywhere with enough substrate. How much area a bag of sawdust spawn covers depends on bed depth and spawn rate, but one bag typically inoculates a bed about 4' x 4'.
- Clear the site of unwanted plants and debris.
- Wet the substrate beforehand, water each layer as you go, or soak the whole bed at the end.
- Wine Caps: start with a 1" layer of substrate and crumble spawn over it, breaking up big chunks. Add another 3–6" of substrate and keep alternating spawn and substrate until you run out of spawn or reach the depth you want. Finish with a top layer of substrate to protect the spawn.
- Almond Agaricus: start with 4–8" of substrate. Break the spawn into 2" chunks and set them 4–6" apart around the bed, burying them a few inches deep at slightly varying depths.
Colonization
Between inoculation and fruiting, keeping the substrate moist is critical. Let colonization take place out of direct sun and check moisture regularly.
