Growing Mushrooms in Coffee Grounds

Mushrooms can be great for your health, which explains their current popularity as supplements. Various species, such as oyster mushrooms, shiitake mushrooms, and lion’s mane, are being consumed for their potential benefits.

However, environmentally conscious supplement users may be concerned about plastic usage and continually buying new supplement packets. Cost may also be a concern.

Those of you will be pleased to hear about the possibility of growing mushrooms in coffee grounds. This method is super sustainable in terms of reducing supplement usage and is a great way to ensure that old coffee grounds don’t go to waste.

In this guide, we teach you how to grow mushrooms from coffee grounds successfully.

Growing Mushrooms in Coffee Grounds: Why Bother?

There are lots of reasons to try this method. Coffee ground mushrooms are pretty similar to anything you can buy in a store, except you get the peace of mind that everything is totally organic since you did it yourself.

Plus, this method is incredibly eco-friendly. Did you know that when you make a cup of coffee, less than 1% of the coffee biomass ends up in your cup? As a result, much of the ground coffee goes to waste – it’s a shame when you think about it!

Keen gardeners might already be aware of the benefits of using up coffee in the soil. So, next time you are about to throw away those used coffee grounds, set them aside, and consider putting them to use instead.


There are other advantages to growing mushrooms in coffee grounds too. Mushroom cultivation requires a sterile environment to reduce the risk of contamination from mold and bacteria. This usually involves pasteurizing the substrate at a high temperature to kill any competing microorganisms.

Coffee grounds are already pasteurized thanks to the brewing process, saving significant time and effort. However, it is essential to use fresh coffee grounds (less than 24 hours old) to ensure they are contaminant-free. Buy your mushroom spawn and other equipment in advance, so once you get your coffee, you’re good to go.

You won’t need too much extra equipment, so this is a simple method that works great for those starting out in the world of cultivating. Oyster mushrooms are an easy crop to start with as they grow vigorously on many different mediums.

Whether you decide growing mushrooms in old coffee grounds is worth it over buying supplements online is your decision. Something different works for everyone. That said, this method is so self-sustaining and straightforward that it’s hard to find an excuse not to try it.

How to Grow Mushrooms in Coffee Grounds

Here is a step-by-step guide on how to grow mushrooms on coffee grounds. The process is relatively simple, so there isn’t much to worry about during this process.

What You’ll Need

  • Fresh coffee grounds
  • Mushroom spawn (oyster mushrooms work best with this method)
  • Straw (optional – see below)
  • Bucket for mixing
  • Mushroom grow bags or other suitable containers (see below)
  • Spray bottle for misting
  • Rubbing alcohol for cleaning
  • Disposable gloves

How to Grow Mushrooms on Coffee Grounds

Step 1: Collecting Coffee and Inoculating

There are different ways to grow mushrooms, but it typically starts with inoculation. This means weighing the mushroom spawn and the coffee grounds to work out how much of each thing you will need.

If you live in a busy city, you should be able to gather coffee grounds from the local coffee shop. Take them an empty container and see if they’re willing to give you their waste. If not, try the next coffee shop until you find one that is willing to help out.


Before inoculating the coffee grounds, thoroughly clean your work surface and mixing bucket with the alcohol and put on the gloves. Then add the coffee to the bucket and break up any lumps by hand.

Make sure everything is fully sterilized before cooking or you risk contamination in your grow space.

Next, add the mushroom spawn, crumbling it into the coffee grounds. As a rule of thumb, use 10% of the amount of coffee. For example, if you are using 1kg of coffee, add 100g of mushroom spawn, and so on.

Some growers also like to add some straw at this stage. It helps to aerate the mixture and prevent the coffee grounds from becoming too compacted. It is not essential if you are using a kilogram of coffee or less. However, larger-scale projects will benefit significantly from the addition of straw. Use approximately 20% of the amount of coffee (200g straw per kilogram of coffee).

Mix everything together, then add it to the grow bags and seal them. You can use other containers, such as empty plastic bottles – just ensure they are thoroughly clean before use. Fill closed containers no more than ⅔  of the way up to allow for gas exchange.

Step 2: Spawn Run

Place the inoculated coffee grounds in a warm, dark place for 2-3 weeks. The ideal temperature is between 68 and 75 degrees Fahrenheit for oyster mushroom spawn.


During this time, the mycelium will begin to colonize the coffee grounds. Mycelium is a network of white, strand-like structures called hyphae. It takes up nutrients from the substrate (in this case, coffee) and produces mushrooms when the conditions are right. When the mixture turns completely white, it’s time to initiate fruiting.

During the spawn run, check the bags every few days for contamination. If you see green, pink, orange, brown, or black patches through the side of the bag, discard them and start again.

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Step 3: Fruiting Conditions

Once the coffee grounds are fully colonized, cut a 1-2 inch hole in the side of the bag or container. If you are growing king oysters, make the hole at the top as these mushrooms like to grow upward.

Move the container to an area with ample fresh air and ambient light. Mist the hole with water twice daily to maintain humidity.


Now, you play the waiting game. You may see mushrooms sprouting within a week, and they will double in size every day.

Keep spraying the mushrooms twice daily and leave them to thrive and get bigger until they’re ready to harvest. On average, it takes about 1-2 weeks in total.

At that point, you can harvest the mushrooms and cook with them or use them to brew tea. Pick them as the caps flatten out and before the spores begin to drop.

The Benefits of Growing Mushrooms on Coffee Waste

There are lots of benefits to growing mushrooms in this way.

  • No need to sterilize the growing medium: Many methods require sterilization of the substrate prior to using it to grow. However, the coffee waste is already pasteurized through the brewing process, so you can cut this bit out.
  • Easy to source coffee: Most of us drink coffee daily, so gathering it is easy. You can also get it in bulk from a local coffee shop.
  • Sustainable: Little goes to waste during this process, which is the best part of this environmentally friendly way of growing. If you want to recycle even more, you can use a large plastic bag or plastic bottle as the growing container.
  • Easy to start: This method is quite straightforward and hard to mess up. Once you have all the things you need, all you need to do is wait!
  • Local food: By growing your own mushrooms, you cut out the middle man that’s required to grow, package, and transport your supplements. As a result, you are saving transportation and commercial growing energy. Once again, this is a super sustainable method.

Things to Avoid When Growing Mushrooms on Coffee Waste

Fungi growth requires healthy mycelium that forms as white strands in your coffee grounds. However, if you see green mold while growing mushrooms from coffee grounds, then it’s time to throw out the project and start again. The same is true for black mold. Experienced growers may be able to cut away the moldy parts and spray the plants with hydrogen peroxide to get rid of it.


Similarly, the mushrooms may shrivel and wither if conditions are too dry. In this instance, move them to an area that is colder and damper. Dryness may also cause them to brown at the edges, which can be solved by spraying them with plenty of water over the course of an hour to rehydrate them.

Final Thoughts: Growing Mushrooms in Coffee Grounds

It’s pretty awesome that you can grow edible mushrooms at home using little more than coffee and a container. You can order mushroom spawn online and get started right away!

What’s more, this is a relatively simple process, and watching your fungal crop flourish is insanely fun! Let us know if you try this method by dropping a comment below – how did your mushrooms turn out?

Ready to take the next steps in your mushroom growing journey? Check out the articles below:

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