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Using cardboard to inoculate a bucket

Buckets are easy to fruit in and don’t require any special equipment.  Typically, the basic growing medium is sawdust.  You can also add other materials if you have them available such as:

  • coffee (urban waste)
  • hardwood wood chips (forestry waste)
  • pasteurized straw (agricultural waste)

For directions on creating inoculated cardboard, see this article:

Prepare bucket

To start, try a bucket that holds around 10L.  You will need some sort of lid.

If the bucket is plastic, drill 1/2″ holes around the bucket.  Approx 12 holes around the outside, and about 3 holes on the bottom.

Tape the holes with masking tape (from the outside).  You will remove the tape later.

You can use other materials.  If you cannot drill holes in the bucket, then you will be encouraging mushrooms to fruit out the top instead.


We suggest starting with a smaller bucket at it will give you a higher chance of success.  Once you figure out how fast the bucket colonizes, then you can move to different sized!

Organize substrate(s)

  • Hardwood sawdust pellets
    • You can purchase them at Canadian Tire.  Ensure you purchase HARDWOOD pellets!
    • This is your base substrate.
  • Spent coffee grounds (optional)
    • If you have access to coffee grounds, here are your criteria:
      • Use spent espresso coffee grounds (drip coffee has too much water)
      • Use coffee grounds within 24 hours of them being used (coffee grounds develop mold very quickly)
  • Wood chips (optional)
    • If you have access to FRESH HARDWOOD wood chips, then you can add up to ~20% to your substrate (by volume)
    • You can purchase hardwood chips in bags from pet stores. They are sold as pet bedding (ensure they are not spruce chips, sometimes they are labeled as Aspen)
  • Straw (optional)
    • If you have access to chopped straw (not hay), you can pasteurize it and add up to ~10% (by volume)
    • You can purchase chopped straw.  Here’s an example of a company:
  • (There are other substrates, but these are the ones we have available and are most familiar with.)

To clarify, you can use (in our experience):

  • sawdust
  • sawdust and coffee
  • sawdust and coffee and straw
  • coffee and straw*
    • *If you are using coffee as your base substrate, then use a SMALLER container – around 1L in size to start
  • sawdust and wood chips

Once you have your materials ready, you need to hydrate them.


Once you have chosen your substrate mix, you need to hydrate it.

First, find a container large enough to mix your substrate in (at least as large as the bucket you are going to use.)  Clean the container with bleach or another disinfectant.

Then, mix your substrate in the bucket.  Add water.  Be patient, wood pellet take a while to hydrate if you are using cold water.  We recommend using hot water.

You want a substrate that is moist but NOT wet.  When you squeeze it in your hands, only one or two drops of water should come out.  If a stream of water is coming out, then add more hardwood pellets or another substrate that is dry.  When the substrate is too wet, the mycelium drown in an anaerobic environment.

Add colonized cardboard

Prepare your bucket (or container) by cleaning it with a disinfectant such as bleach.  If you are going to use scissors or a knife to cut the cardboard, disinfect those tools.

Wash your hands very well.  Wear clean clothes or a clean apron.  Work in a clean environment.

Add some of your substrate to the bottom of the bucket.  About 5 cm.

Create a single layer of cardboard.  You can use a flat layer (i.e. one piece cut to size) or cut up the cardboard into smaller pieces.  Do not layer cardboard pieces on top of each other.  Getting cardboard to the outside edge of the bucket is more important than the middle.

Add some of your substrate on top of the cardboard.  About 5cm.

Create another layer of cardboard.

Repeat.  Ensure the last layer is substrate.

Cover the top with a loosely fitting cover.


Place the bucket in a dark (optional) area with a temperature of at least 15°C.

Do not place the bucket in a drafty area – the moisture loss will be too great.

Each day, check for mold.  If there is mold on top, you can attempt to remove the mold (with a clean tool).  If there are large amounts of mold, add the contents of the bucket to the compost bin. Better luck next time!

Each day, check for moisture.  If the substrate is drying out, spray the top with water.  It’s best, if you are using city water, to let the water stand for a few hours before using it.  This allows the chlorine to evaporate.

To check how far along the substrate has colonized, peal back some of the masking tape and look!


Once the bucket is colonized, remove the tape from the holes.

You can optionally remove the lid.  If you do, ensure you consistently mist with water to keep the moisture/humidity level up.

Mushrooms will fruit from the holes!  Harvest the mushrooms before they start to sporulate. You can tell they are about to drop spores when the edges of the mushrooms start to curl upwards.  You will also notice they start to dry out.

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