Mushroom 101: Grow Your Own

Illustration by  Ashley Barlow.

Illustration by Ashley Barlow.


First, let's set one thing straight. Mushrooms are not actually plants, but fungi. Fungi eat, or break down dead plants for fuel. Standard mushrooms can easily be identified by the dome or cap shape protruding from the stem. If you look under this smooth dome, you'll see thin gills. Those gills produce the mushroom's spores. Mature mushrooms proliferate in a similar fashion to plants, producing tiny spores that act as seeds and allow for the fungi to spread and grow.



METHOD coffee+cardboard
This is one of the easiest ways to grow mushrooms at home. It's also a cool food science project that will require very little active time and is something you can do while you make breakfast and the morning cup of coffee. Simultaneously you are creating a high value compostable material from which the residual caffeine, a mildly toxic herbicide, is largely degraded by the fungus. 


  • 20% coffee grounds and 0.5 kg of spawn (we suggest starting with Oyster Mushrooms.) to produce about 1.25 kg of mushrooms.
  • Spent cardboard or paper products without glossy inks. 
  • Container or bucket with lose fitting lid.  
  • A warm and dark place to store your bag/container.

Step One  
Freshly brewed coffee grounds from a coffee maker or french press are effectively pasteurized by the brewing process so once it has cooled below -100F you can inoculate it directly with purchased grain/sawdust spawn or cuttings from fresh mushrooms.

Step Two
Cardboard or paper products can be shredded and boiled in water and once excess water is drained or pressed out this too can be inoculated with spawn or cuttings. 

Step Three
 It is best to start with a small amount of both growing media (coffee/paper) and some inoculum (spawn/cuttings). The mycelium is very often visible at the base of mushrooms and will readily "jump off" and begin to "run" into a new food source within its reach. Place these cuttings in direct contact with the cardboard to provide as many jumping off points as possible. Once you've got a half a five gallon bucket or so of colonized cardboard you can turn around and use this cardboard as spawn to inoculate a second bucket started with a few layers of new cardboard, some cardboard spawn, a fresh but cool coffee filters/well drained grounds, more spawn and another couple layers of new cardboard. 
Step Four
About three weeks later you should see some mycelium establish itself and the mixture should start to turn completely white. From here on out as you generate coffee waste you can add it to the top layer, add some fresh spawn from the first bucket, and add a little more new cardboard to seal in moisture above the spawn. Repeat until bucket is filled. 

Step Five
Once your mix is completely white move your growing container over to a spot with plenty of fresh air and a little light – a shaded windowsill or countertop is ideal. Drill 1/2'' holes near the top of the bucket for ventilation. Check every couple days to see if the top layer is drying out. If so you can mist it with de-chlorinated, or off-gassed tap water.

Step Six
About a week later you should start to see tiny little mushrooms bursting into life. Over the following 5-7 days they should double in size every day. It's time to harvest when the edges of the caps begin to turn upwards. Remove mushrooms by cutting at the base of the stems.

White mycelium running up onto un-colonized cardboard.

White mycelium running up onto un-colonized cardboard.

Thanks to amateur mycologist and educator Martin Gordon for your contributions to this post!