How to Grow Mushrooms In Coffee Grounds. Step By Step Guide

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Mushrooms are easy to grow, and coffee grounds make a perfect growing medium for mushrooms. It is because mushrooms can obtain all their nutrient requirements from coffee grounds. Also, coffee grounds have sufficient air spaces to allow for the spreading of mushroom spawns.

If you are starting out growing mushrooms, the experience might be intimidating at first. I have prepared this guide to help you through the process of growing mushrooms on coffee grounds. Read on and find out more.

Growing Conditions Required for Growing Mushrooms

Growing mushrooms is a very profitable venture because they are not demanding. However, it would help if you had the growing conditions to grow mushrooms. This section will look at the growing conditions for the rapid growth of healthy mushrooms.


Mushrooms obtain their nutrients from organic matter. Some of the essential nutrients for mushrooms include nitrogen, protein, fats, lignin, starch, and sugar. Coffee grounds are rich in nutrients, making them suitable for growing both button and shiitake mushrooms. Once you are don’t grow mushrooms, you can add this waste to your compost.


Like other fungi, mushrooms grow in moist environmental conditions. The moisture conditions for growing mushrooms range from 35 to 45 percent. Once you grow your mushrooms, you need to ensure you maintain these conditions by spraying with water daily.


Growing button mushrooms at 55 F to 60 F would be best. To maintain these temperatures, you should also remember that dry air and strong draft can pre#vent growth or kill already growing mushrooms. Shiitake mushrooms grow at temperatures of 40F to 90F. Growing mushrooms indoors might require heaters and fans to maintain these temperatures.


It would help to remember that they do not require light to synthesize their food as you grow mushrooms. This factor shouldn’t bar you from growing mushrooms outdoors—however, growing mushrooms in the dark help in preserving the moisture content the pores require to reproduce. Growing mushrooms indoors, you can consider the basement or under the kitchen sink, which provides the perfect growing conditions away from direct sunlight. Remember that mushrooms thrive in dark, calm, and humid growing environments.

What Makes Coffee Grounds a Perfect Medium for Growing Mushrooms?

Mushrooms rarely grow on garden soil like plants. They require a medium that is not too dense for the growth of their delicate spawn. Coffee grounds make a perfect medium for growing mushrooms due to fine and light particles.

They also allow air to flow, which is critical for mushroom spawn growth. As a result, coffee grounds are one of the most recommended mediums to grow different types of mushrooms.

Another reason you would find coffee grounds a perfect medium for growing mushrooms is because they are already a waste resource, and it would be wasteful to throw them away.

Coffee grounds are also packed with nutrients that make them perfect for growing mushrooms. As we saw earlier in this post, mushrooms require several nutrients abundant in coffee grounds.

The growing medium for mushrooms has to be sterilized, and this process is not necessary when using coffee grounds as they are readily sterilized during the brewing process.

Also, coffee grounds absorb moisture maintaining a perfect environment for developing mushroom spawn.

You may also like to read this post: Are coffee grounds good for vegetable gardens?

What You Need to Grow Mushrooms In Coffee Grounds

You can grow mushrooms in a transparent jar, container, or growing bag. If you choose to grow them in a pot or container, you will need a well-fitting lid/ cellophane and microporous tape, which you can purchase from a drug store.

You can also get another medium to break the compact coffee grounds such as saw, dust, straw, or cardboard. Finally, you will then need spent coffee grounds and mycelium. Mycelium is a vegetative fungus that produces mushrooms obtained from mushroom farmers.

The coffee grounds must be fresh to prevent contamination, and ensure you use them within 24 hours of brewing. The coffee grounds must also be adequately cooled down as the heat might kill the mycelium when still hot.

Steps for Growing Mushrooms in Coffee Grounds

Wash or sterilize your hands.

Before growing mushrooms, you must wash or sanitize your hands properly. One of the significant challenges mushroom farmers face is contamination, whereby they breed other fungi, mold, and bacteria that compete with the mushrooms inhibiting their growth.

Drill holes on the lids

Secondly, you need to drill two to three holes in the lid. It is easier to drill than against the wood with the lid sandwiched between.

Sterilize the containers

It would help sterilize the lid, jar, or container using boiling water. If possible, dip the containers in the water for 60 seconds. Bear in mind the material of the container or jar, as it might break or crack when immersed in boiling water.

Alternatively, to avoid damage from hot water, you can sterilize them by rubbing alcohol on the container, jar, and lid.

Dry containers and cover them tightly

After sterilizing, dry them properly and leave them covered. Use microporous tape to cover the holes on the lid to prevent access by bacteria. If you don’t have lids, you can use them.

Sterilize Coffee Grounds

Sterilizing these components is critical to prevent unwanted growth. You can do so by pouring boiling water on them and allowing it time to cool down.

Mix the Mycelium

Use sawdust to break the mushroom spawn and ensure even distribution in the container. Mix the components further in the container with the coffee grounds. The mixtures should be in the ratio of mushroom to coffee grounds should be 1:10. The amount of sawdust should be a fifth of the total weight of the coffee grounds.

If they are dry, moisten them. Cover the container adequately and store it in a dark place. You need to ensure that the holes you drilled are left open to allow the free flow of air.


Also, ensure the temperatures are maintained at 20°C to 25°C and let them sit there for some days. You can refrigerate to maintain this constant temperature necessary for the growth of the mycelium. You will begin to notice the mixture turning white gradually until it is entirely white.

Bring them into fruiting conditions.

Once the entire content turns white, remove the container from the refrigerator and place it in a humid light at 20°C away from direct sunlight. Remove the lid and spray the mushrooms with water once or twice daily. Replace the cover every time after watering, and after two weeks to ten days, you will notice your mushrooms start to develop. They should emerge through the holes in the lid or cover.

Mushrooms develop very fast, doubling in size every day, and they are ready for harvesting when the top begins to flatten. However, it all depends on the type of mushroom.

If you start noticing mold growing on the coffee grounds, it could be due to excess water. To control the growth of these molds, transfer the mushrooms to a lower-temperature environment and reduce the amount of water you are spraying.

If you wish to experience a less difficult time fighting these unwanted growths, maintain the required growing conditions, as we say above.

Harvesting mushrooms

Harvesting mushrooms is very easy; you can twist the cluster or cut it with a knife. You can grow mushrooms for three rounds before exhausting the mycelium. After harvesting, you must keep the container under the same conditions and spray water once or twice daily to encourage new growth.

Where Can You Get Coffee Grounds?

As seen earlier in this post, your coffee grounds should be fresh and not more than 24 hours old. Getting enough of these coffee grounds from your kitchen might be possible. However, you can talk to your nearest coffee shop and provide them with a collecting container. Used coffee grounds are usually wasted, and they are often thrown away, so this way, you can get sufficient amounts for growing enough mushrooms to feed your family and friends.

Which Mushrooms Varieties Can Be Grown In Coffee Grounds?

If growing mushrooms for the first time, you must be careful with the variety. All in all, your harvest will depend on the amount of care you provide from the start.

Here are some mushroom varieties that do well when grown on coffee grounds:

Oyster Mushrooms

These are some of the most commonly grown mushrooms and the easiest for beginners. Oyster mushrooms grew widely on dead trees and were first cultivated by German soldiers during world war I. Growing this variety of mushrooms is much easier because they are resistant to competitors such as fungi and bacteria.

The incubation period of oyster mushrooms is usually ten to fourteen days. During this period, you need to store the material in the dark at temperatures of  20-24C/68F-75F.

For fruiting, bring the containers or bags from incubation to autumn conditions with low light, high humidity, cooler temperatures, and more oxygen. The mushrooms should become fully grown and ready for harvest within five to seven days.

Like most mushrooms, you can harvest oyster mushrooms in three cycles before the mycelium becomes thoroughly exhausted. After the first harvest, you should expect a new crop every five to seven days.

They are loved for their delicious taste and are also nutritious. Another advantage of growing oyster mushrooms is that they grow very fast when grown on coffee grounds.

Like any other mushroom, you need to provide them with just enough water and maintain the required temperatures depending on their growth stage. Don’t forget to sanitize all equipment to avoid contamination.

Button Mushrooms

Button mushrooms, also known as white or white button mushrooms, grow well on coffee grounds and are some of the most straightforward mushroom varieties you can grow at home. Many gardeners are now familiar with these mushrooms, significantly contributing to their increasing popularity. When raw, they have a bland taste which becomes earthy when cooked.

They are usually relatively small, with capsizes of two to seven centimeters. The caps are white, rounded, and smooth. These mushrooms take between 30 to 35 days to reach full maturity. At harvest, the fruit or cap should be tightly closed.

You can grow button mushrooms all year round, including winter, as they do not require sunlight.

Shiitake Mushrooms

Shiitake mushrooms are native to East Asia and are usually dark brown. Their caps are medium-sized with a diameter of five to ten centimeters.

Shiitake mushrooms do well on coffee grounds. They are, however, not as easy to grow as they require more attention. The incubation period for shiitake mushrooms is also longer because they are not as aggressive as other varieties.

Shiitake mushrooms are worth the effort as they are more productive than other varieties. If you do everything right, you will enjoy a good harvest.

Some studies suggest that shiitake mushrooms are unsafe when eaten raw in large quantities. These mushrooms can cause skin swelling, blood abnormalities, and stomach discomfort. In some rare cases, it causes breathing difficulties, makes the skin more sensitive to the sun and leads to skin allergic reactions.

Shiitake mushrooms taste better when cooked with a rich, meaty, and buttery taste.

Portobello Mushrooms

Portobello mushrooms are the full-grown stage of button mushrooms. They are widely used as beef substitutes for vegetarian burgers due to their delicious taste and large size. These mushrooms do well in coffee grounds, and due to their size, you will need more coffee grounds and containers to grow them.

These mushrooms have a white stem and a thick brownish cap. These mushrooms take three to four weeks to grow fully. However, they are edible at any stage. You also harvest in three clusters before you exhaust the mycelium.

As you grow these mushrooms, keep in mind that they require higher amounts of water because their skin is not tough enough to hold moisture.

During periods of low humidity, Portobello mushrooms lose a lot of water and require more moisture. Too high humidity is also dangerous for these fungi as it causes an increase in bacteria activity which increases competition for food and oxygen.

You can grow these mushrooms both indoors and outdoors. However, they are easier to care for when grown indoors.

Why You Shouldn’t Eat Raw Mushrooms

Mushrooms are best eaten when cooked. Research findings suggest that all raw mushrooms contain carcinogenic compounds called hydrazine. This compound has formaldehyde which is heat sensitive and is destroyed when exposed to high cooking temperatures.

Other ways you can grow mushrooms.

Another popular way to grow mushrooms is on hardwood logs. These will harvest for approximately 7 years, but it takes much longer before they are ready to fruit if you want to know more about that, check out the video below.

I also wrote an article on the subject, which you can view here—how to grow mushrooms on logs- step-by-step how-to guide.


Mushrooms are challenging to grow, and it might take some skill to get it right. The biggest challenge you will likely encounter when growing mushrooms is contamination, which encourages mold and bacteria growth.

For this reason, you need to follow through with the steps I covered above. Also, remember to provide the proper environmental conditions. Don’t be discouraged if you fail the first time; instead, try again. It’s worth it!

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