Coffee Experiment

Can you grow mushrooms on coffee grounds?



This experiment allows you to observe the life cycle of a mushroom. You will learn how mycelium (the root of the mushroom) colonizes its substrate, fruits mushrooms, and releases its spores.


The mycelium is a living organism, and it is still alive on the sawdust block from your last kit. When you transfer the mycelium-infused sawdust into the glass jar and layer it with coffee grounds, you are giving the mycelium a new energy-rich substrate on which to grow.

You see, unlike plants, which use their chlorophyll to make their own food through a process called photosynthesis, fungi do not make their own food. Instead, fungi obtain nutrients by breaking down organic matter or obtaining it directly from higher plants. Therefore, you will see the mycelium, which is made of string-like cells called hyphae, colonize (spread throughout) the new substrate (the coffee grounds) to “eat” its nutrients.

After the mycelium colonizes the substrate in the jar, it is ready to begin its reproduction process. The mycelium germinates mushrooms, which contain spores in the caps (the tops of the mushroom). When the mushroom ages, it drops its spores. If the mushroom had grown in nature, the spores would be released into the air in the hopes of being fertilized and landing somewhere ideal where the mycelium can continue to grow.

Materials Needed:


  1. Take the spent sawdust block out of the grow box of your 100th Monkey Mushroom Farm mushroom kit.
  2. Remove the sawdust block from the bag. Throw away the bag and grow box.
  3. Crumple the sawdust block into flecks of sawdust.
  4. Put the sawdust in a plastic container and secure (tightly close) the lid.
  5. Pour in 1 cup of non-chlorinated lukewarm water into the container and shake it.
  6. Put ¼-inch layer of sawdust in the bottom of glass jar.
  7. Cover the sawdust layer with ½-1 inch of coffee grounds. You don’t have to measure the coffee grounds exactly. If you use coffee filters, you can take the entire coffee filter with the coffee grounds in it and lay the filter in the glass jar. The mycelium will break down the coffee filter.
  8. Put down another ¼-inch layer of sawdust.
  9. Continue layering the coffee grounds and sawdust until the mixture is 2 inches from the top of the jar. Note: You can do this all in one day if you have saved enough coffee, or you can add the coffee-sawdust layers day by day as the coffee grounds become available.
  10. Either set the lid on the jar offset by ⅛-inch or drill a hole in the lid ⅛-inch in diameter.
  11. Put the jar in a dark place, such as cupboard, cabinet, closet, for approximately 2-3 weeks.
  12. After 2 weeks, begin to check the jar daily to see if small mushrooms (primordia) are forming. When you see small mushrooms growing, take the jar out of the dark and put it on the counter, but not in direct sunlight.
  13. Take the humidity tent that you used to grow your other mushroom kit and place it in the same manner over the jar. Follow the same method you did with your previous kit and mist the inside of the humidity tent several times a day, making sure that you always see condensation on the inside of the tent.
  14. In 3-5 days, the mushrooms should be in full bloom.
  15. Do not pick the mushrooms. You have yet to observe the liberation of the spores, which then continue
    s the life cycle of the mushroom. After the mushrooms have passed their prime and start to become a bit wilted, but before you see a fine, white powder on and around the jar.
  16. Take the stalk off of the mushroom and place it on a dark piece of paper. Leave for 24 hours to allow the spores time to drop. You are making a spore print! (See our “Making a Spore Print” activity for additional ideas of to do with your spore prints.)