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Coffee Recycle
Mushroom Kit

Mushrooms are the world’s greatest recyclers. Without them the earth would be drowning in un-decomposed organic material and deprived of the carbon rich soil that supports life. In the wild, mushroom mycelium grows on organic material such as leaves, logs or dead trees. It breaks down this material and produces mushrooms in the process. Oyster mushroom mycelium is very vigorous and can grow on many organic materials. Several things in our homes make good growing medium for oyster mushrooms: spent coffee grounds, used tea bags and cardboard. In mushroom cultivation, it is important to pasteurise growing medium to minimise competition from other fungi (such as mould or yeast). Spent coffee grounds and used tea bags make ideal growing mediums because they have already been pasturised by boiling water. Cardboard can be easily pasturised by pouring boiling water over a colander filled with ripped up cardboard and letting it drain.

Each species of mushroom is a different growing experience. Even if you have grown mushrooms before, please read the instructions for your kit carefully before proceeding. If you run into any problems please see our FAQ.

Materials Required: 

If you are not starting your mushroom growing project immediately, please store your BLUE oyster spawn in the refrigerator or PINK oyster spawn in a cool place for up to a month.

  • 1 clear jar or plastic container with a lid (approx. 1 - 5L).

  • 1 large or 2 small cotton balls

  • 1 packet of oyster mushroom spawn

  • Cardboard, (freshly made) spent coffee grounds & tea bags

  • Clean spray bottle


The size of the container you choose should be relative to the amount of tea or coffee you regularly use.

Step 1. 

Make a hole (approximately 3-6cm in diameter) in the lid of your container.

  • Fill this hole with a ball of cotton wool so your mycelium can breathe.

  • This lid will keep out competing fungi and bacteria and and the cotton will allow your mycelium to breathe.

  • Your mushrooms will eventually fruit from this hole.


Step 2: Choosing your growing medium

You can use spent coffee grounds, used teabags or cardboard. We suggest using a mixture of the three for best results. Any growing medium should be room temperature before you add it to your container.

  • Spent Coffee Grounds

    • If you will be primarily be using coffee grounds you will need to alternate between layers of coffee grounds and layers of cardboard and/or tea bags. Coffee grounds are quite dense and do not provide adequate growing structure on their own.

    • Spent coffee grounds are also prone to competition from other fungi like mould, so use small amounts for each layer and be sure to let your mycelium grow quite a bit before adding a new layer. 

    • It is best to use an espresso machine or percolator rather a cafetiere (which will leave your coffee grounds too wet).

  • Cardboard

    • For cardboard, pour a kettle of boiling water over a colander of cardboard ripped or cut into 1 inch pieces. Let it drain and cool.

      • Cardboard is usually made from softwoods and using it alone will lead to diminished yields of mushrooms. We suggest combining cardboard with coffe grounds and/or tea bags.

  • Tea bags

    • Tea bags should be wrung out well. Do not squeeze them with your fingertips, but use 2 clean spoons instead.

Step 3: Starting your mushroom growing container
  • Clean the inside of your container thoroughly.

  • Add a 2 cm layer of growing medium to the bottom of your container.

Step 4: Adding your spawn

Wash your hands well and thoroughly break up your spawn inside the bag.

Pour the spawn inside on top of the growing medium.

close the lid and be sure the cotton wool is firmly in place.

Step 5: Incubation & adding layers of growing medium
  • Place your closed container somewhere dark. A kitchen cabinet is often a good choice. You want to keep your container warm but not too hot. Between 17-25° is ideal.

  • The surface of your growing medium will begin to grow white mycelium.

  • When the majority of the surface is covered, it is time to add a new layer of growing medium.

  • Return the closed container to the kitchen cabinet and repeat until your container is completely full of white mycelium.


White mycelium is beginning to grow on the layer of growing medium

The surface of the growing medium is almost compleatly covered in white mycelium and is ready for a new layer.

Step 6: Fruiting

Once your container is completely full of white mycelium and growing medium it is time to fruit.

  • Remove the cotton wool and place your container in an area with high humidity and indirect sunlight.

  • Optimal fruiting temperature is 16-20 degrees.

  • When you see baby mushrooms begin to grow, spray them with clean water.

Step 7: Harvest

Harvest your mushrooms when the caps have just begun to flatten but before they start of brown at the edges, become ragged or turn upwards. If your mushrooms do drop spores they're still edible but may be slightly less tender.


To harvest, twist and pull your entire bunch from the hole. Be sure that you have not left any of the mushroom stem in the hole or attached to the growing medium. your mushrooms when the caps have just begun to flatten but before they start of brown at the edges, become ragged or turn upwards. 


We hope you've enjoyed growing your Blue Oyster mushrooms!

We're passionate about sharing the diversity of the fungi kingdom & making more  of its edible & medicinal delights easy to grow. Want to try another strain or learn how to cultivate mushrooms? See our full range of mushroom growing kits and cultivation workshops!

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