Prepare Mason Jars

Prepare Mason Jars

Prepare your mason jars before adding the coffee grounds to them.

Drill a Center Hole

To begin, grab your drill and a 1/8-inch drill bit to drill a hole in the center of the jar's lid. The hole should be large enough to be stuffed with poly-fil, which you will do soon.

Drilling Hole in Lid

Clean Shards and Debris

After drilling the hole, you will likely see that sharp edges have formed on the underside of the lid where the hole is. Carefully scrape these off to avoid cutting yourself in the future. You can also use a hammer to flatten the sharp edges. Also, clean out any debris in the jar and quickly wipe it down with 70% alcohol.

Flatten Shards with Hammer

Clean Jars

Using warm and soapy water, clean the mason jars and their lids. Allow them to air dry or wipe them dry with a towel.

Washing mason jar

Stuff Lid With Poly-fil

Grab a handful of poly-fil and twist it to pull it through the lid's hole. It should fit snugly enough that you can't easily pull it out.

Handful of Poly-fil

Pulling Poly-fil through lid

Use scissors to cut off any excess poly-fil if it is over one inch on either end. Then, cover the top of the jar with aluminum foil.

Cutting Off Excess Poly-fil

Jar with Lid Stuffed with Poly-fil

Repeat this process for all of the jars.

Sterilize Jars

Set your oven to 350 degrees Fahrenheit, and allow your jars to sit inside it for 15 minutes. Also, boil a pot of water and add a spoon or two for 3 to 5 minutes. You will use the spoon to scoop in the coffee grounds later.

After, sit the jars and spoons out to cool down to room temperature before moving forward. If your oyster mushroom spawn was in the fridge, pull it out and allow it to warm to room temperature.

Mason jars and spoons sitting out