Upscale your coffee grounds into a mini mushroom garden

Tasty, delicious, and garden unfriendly, oyster mushrooms thrive in a cozy bed of coffee grounds. In addition to making a tasty gift, mushrooms are also a great source of selenium, a powerful antioxidant that helps support the immune system and prevent cell and tissue damage. Mushrooms grow best in porous, sterile, slightly moist soil known as substrate. The optimal substrate is very easy to achieve with a combination of used coffee grounds and straw or sawdust. Harvestable mushrooms should start to appear within two weeks of creating your mushroom bed.

What you will need

Clean, sealable, breathable plastic bags, such as food storage bags or filter spawn bags.

A clean pale or pot for mixing.

2-3 cups of just-brewed, moist coffee grounds. For a successful garden, you will need coffee grounds that have been brewed within the past 24 hours. Grounds older than 24 hours are likely to be dry and may have started to mold. Coffee grounds should comprise 77% of your substrate’s total weight.

Pasteurized straw or sawdust equal to 15% of the total substrate weight or 20% of the weight of the coffee grounds.

Oyster or shitake mushroom spawn equal to 8% of the total substrate weight or 10% of the weight of coffee grounds.

One medium-sized or several small crates, boxes, or baskets with an open top.

Making a mushroom bed

Step 1: Mix your coffee grounds and straw or sawdust until well integrated.

Step 2: Add your oyster mushroom spawn to your substrate and mix until very thoroughly combined.

Step 3: Transfer your mixture into the breathable plastic bags and seal.

Step 4: Turn your mini mushroom gardens upside down so that the bag’s seal is on the bottom and shake your bag to ensure the top (the side without the seal) is level. Place your mini mushroom gardens into your crate(s) or container(s).

Step 5: Poke 2 to 4 holes in the tops of the breathable plastic bags.

Step 6: Store your mushroom garden at room temperature, out of sunlight until the coffee grounds are covered with a white covering, known as mycelium. This first process generally takes between 7 and 14 days. When most of your coffee grounds have mycelium on them, your spawns have colonized the substrate.

Step 7: Once colonized, move your garden to a spot with good airflow, indirect sunlight (mushrooms need some sunlight to grow), and away from direct heat. Mushrooms will grow best in a spot that fits these criteria and cools down a bit in the evening, such as a windowsill.

Step 8: Using scissors or a small knife, cut a cross on the top of your bags, being sure not to damage the mycelium while cutting.

Step 9: Gently mist your garden a few times per day to keep the mycelium moist.

Step 10: Harvest your mushrooms and enjoy!

Grown and giving tips

Below are our basic tips for growing your mushrooms. If you would like more detailed information, please visit the blog entries, noted below, that were provided by Danielle of North Spore, an innovative company with a team of experts in all things mushroom.

  • Be sure to keep your garden moist at all times. Mushrooms cannot grow without moisture.
  • Avoid placing your garden in an area that gets too warm (above 70°F) or too cold (below 62°F).
  • If you are giving an oyster mushroom garden as a gift, include a little spray bottom for misting and a card with care instructions included.
North Spore resource references:

Mushroom Garden

Outdoor Mushroom Beds


The health benefits of mushrooms

Using Coffee Grounds in the Garden

Gourmet Woodland Mushrooms

Growing Mushrooms In Coffee Grounds

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