What is Coffee Bloom (Why & How to Bloom Coffee)

Are you sick of drinking bad coffee, brewed from stale old beans… Would you like to know how to tell if you’re brewing with fresh beans that will taste as good as barista made coffee?

Coffee bloom is the secret to unlocking flavors in your coffee that you never knew existed. It is tied with the reason all coffee aficionados tell you to buy freshly roasted coffee. With a few simple steps, you will be able to bloom your coffee and change a mucky, sour, or flat coffee into a vibrant, well-balanced, and nuanced flavor bomb.

You might have heard of coffee bloom before, but never truly understood the science behind it and how it affects your coffee.

Coffee bloom is the one drawback of buying extremely fresh coffee beans. It is the result of trapped carbon dioxide in the coffee bean that is released when brewing. This is caused by the hot water coming in contact with the fresh coffee grounds.

Coffee Bloom Explained Scientifically

You may have heard about coffee bloom when watching some YouTube videos or reading articles online and never really understood what it is and how it affects your coffee.

It is a common phrase and important part of brewing pour over coffee. There are a lot of misconceptions about coffee bloom and what it does to the flavor of your coffee.

I am here to clear up all the confusion.

Coffee bloom is a good sign that you coffee beans are freshly roasted. The roasting processes causes carbon dioxide to be trapped inside the coffee bean. If you’d like to learn how to roast your own coffee beans at home read our article on home roasting.

If you are familiar with coffee roasting you will know that many roasters judge the “doneness” of the coffee beans by the cracks that occur during roasting. These cracks are caused by the buildup of gasses from the heat converting complex carbohydrates into other molecules. This conversion creates sugars, water vapor, and carbon dioxide.

Over time the coffee beans release this gas in a process called degassing. This is why roasters often wait a few days before selling the freshly roasted coffee beans.

The Importance of Coffee Bloom and Why You should Bloom your Coffee

Inherently carbon dioxide isn’t a bad thing. However, when inside a coffee bean, the carbon dioxide is the thing blocking you from the amazing flavors trapped inside the coffee beans or grounds.

The carbon dioxide is an important signal or freshness in roasted coffee beans:

It is an indicator for freshness, plays an important role in shelf life and in packaging, impacts the extraction process, is involved in crema formation, and may affect the sensory profile in the cup

2018 report in the Journal of Agricultural and Food Chemistry

However, if your coffee beans have not degassed the beans for long enough and you do not properly bloom your coffee the carbon dioxide inhibits the contact with water.

When in contact with water the carbon dioxide escapes and forms bubbles that disrupts extraction of the coffee beans.

For coffee roasters that roast their own beans, it is best to wait at least 96 hours before grinding and brewing freshly roasted coffee beans. The darker the roast the less carbon dioxide they will have so they will have to degas for a shorter amount of time.

Another reason you want to degas your coffee beans besides reducing the amount of carbon dioxide that is present during the bloom is because the carbon dioxide also imparts a bad flavor into coffee.

Carbon dioxide has a slightly sour taste. This is something that we don’t want in our coffee and can shift the flavor of all our coffee to a slightly acidic flavor. If you regularly brew sour coffee this may be the cause.

How to Bloom your Coffee

There are different ways to bloom your coffee and remove the carbon dioxide for every different way you brew your coffee. While each blooming method is different the concept is the same.

Remove the carbon dioxide from the coffee grounds so you can get the best flavor out of the beans.

How to Bloom French Press Coffee

This is the simplest method of blooming coffee and it will have the least effect on the end product because of the long contact time the coffee beans have with the water. To bloom french press coffee:

  • With your coffee grounds in your french press pot pour in just enough water to wet all the coffee grounds.
  • Wait 30 seconds for the carbon dioxide to escape. You should see a small layer of gas bubbles forming.
  • Stir the coffee grounds so everything is wet and saturated then continue brewing.

For a guide on how to brew the perfect french press coffee you can check out our article here.

How to Bloom Pour Over Coffee

It is very important to bloom when using a pour over coffee brewing method. This is because the water passes through the coffee grounds fairly quickly and if the carbon dioxide inhibits the contact with water you will lose precious flavor in the coffee grounds. To bloom pour over coffee:

  • Put your coffee grounds in the pour over coffee filter in preparation of brewing.
  • Using just enough water to wet all the coffee grounds carefully pour in a circular motion so all the coffee beans get wet.
  • Allow the wet coffee beans to sit for 1 minute before continuing your brew.

If you want to learn how to brew pour over coffee like the world coffee brewing champion check out our article about the best V60 brewing method. We compared three of the most famous brewing methods and chose our favorite. Click here to read more.

How to Bloom for Manual Espresso

You might not have know you could bloom your espresso, but if you have a manual coffee maker like the Flair Espresso Maker you can effectively bloom your coffee and brew better espresso every time. To bloom your espresso:

  • Have your portafilter filled up with coffee and equipment heated.
  • With your manual coffee maker pour in the hot water needed for a shot and lightly apply pressure for 10 – 15 seconds. You will need about 2 bars of pressure to pre-infuse and bloom your coffee.
  • Brew your espresso!

If you are interested in learning about the flair espresso check out the article here. It is an interesting way to manually brew a great espresso shot. You have control of all the factors to brew a great espresso. If you want to learn how to brew amazing shots with it read this article.

How to Bloom Automatic Coffee

For this last method you can improve the coffee your automatic coffee maker brew with three simple steps. This is something most people would not know they could even try, but it will make a huge different to your daily coffee. To bloom for an automatic coffee maker:

  • Put your filter and coffee grounds into the automatic coffee maker’s coffee basket
  • Pour just enough water to get all the beans wet over the coffee grounds in a circular motion.
  • Let the coffee grounds soak for 1 minute then continue brewing your automatic coffee as normal accounting for the slight bit of extra water you added.

How to Keep Your Coffee Fresh and How it Affects Coffee Bloom

Now that you know how to bloom your coffee you can combat the carbon dioxide that is stuck in your freshly roasted coffee beans. Now, you will have to learn how to keep your coffee beans fresh and what factors affect the amount of carbon dioxide is inside your bean.


If you are interested in learning how to properly store your coffee beans so they stay fresh for the longest amount of time you can read our article here.

It is best to keep your coffee beans in a dry cool place in a airtight container.


The hotter the beans are the faster the gas will escape from your bean and the faster the beans will go stale. To preserve the flavor of your beans you should keep them in a cool place.


In a dry location the coffee will lose gas faster than in a humid area. However, this is better than the alternative. In humid areas mold and fungi can grow inside the coffee grounds. The coffee grounds are a great medium for fungi and they can produce harmful toxins if they grow inside your coffee grounds. For the best results find an compromise between humid and dry.


Now that you know everything you need to know about blooming coffee go and enjoy better coffee!

Report back to this article if you try this and taste a difference.


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