What Exactly is a Coffee Bloom? And Why Bloom at All?

It doesn’t matter if you have the best coffee maker you can get your hands on, if you lack some of the basic coffee brewing fundamentals you’ll still struggle to get a good tasting cup on par with your local coffee house.

Like everything knowledge is the key, the more you learn regarding brewing coffee at home the better you’ll be. If you’re not ready to put in a bit of leg-work and spruce up your coffee brewing technique maybe you’d be better off going back to instant coffee.

I notice a few of you reading this have run off back to your Nescafé instant, but for those of you still sticking around I will be talking about the coffee bloom in this article. The “coffee bloom” is one of the key variables that can transform your coffee from a mucky sour brew to a perfectly tasting cup good enough to impress any bearded hipster barista.

What The Heck is a Coffee Bloom?

The coffee bloom is a natural part of any brewing process and the “bloom” starts when the hot water hits the grounds causing CO2 gases to become released (If your coffee is fresh, it’s releasing CO2 which repels water). As you introduce a small amount of water (just enough to get your coffee wet) to your coffee grounds the CO2 is expelled out of the cells of the coffee, which by the way contain all those oils and aromatics, the fresher your coffee the bigger the bloom.

The coffee bloom typically lasts for 30 seconds and you should see your coffee grounds start to bubble and expand into a dome like shape, at this stage you can continue with your pour. Giving your coffee 30 seconds to bloom will enhance its flavors (depending on how recently it was roasted).

…Still with me? So basically the coffee bloom allows the water to displace most of the CO2 which then essentially preps the coffee bed for a proper extraction. If you don’t see a coffee bloom it most likely means that your coffee isn’t fresh and most of the de-gassing (releasing of CO2) has already occurred and unfortunately along with that most of the flavor compounds within the beans will have also deteriorated.

As far as I am aware, the coffee bloom happens in every non-espresso extraction and other brew methods that use fresh coffee.

Variables That Can Affect the Bloom

The coffee bloom doesn’t “just happen” there are many variables that can play a role in the releasing of CO2 and in-turn can have a negative impact on your bloom. I have listed below a few of the factors that can impact the rate at which the CO2 can be lost the moment the coffee beans leave the coffee roaster, let’s take a closer look.

Storage Temperatures

If you store your whole coffee beans in a hot place expect the coffee beans to lose CO2 rather quickly (not good). I recommend storing your whole coffee beans in an airtight container in a cool dry place and away from direct sunlight, at the back of a kitchen cupboard is a great place (as long as it’s not over your stovetop!). Check out my article on How to Store Coffee Beans for more storage tips. Remember: Heat means more gas release and you want to avoid this.

Humidity and Coffee Beans Don’t Mix

Just like heat, dry humid storage conditions will allow for more CO2 to escape. Not only that, humid environments can also encourage fungus and mold to grow on your beans (not good).

Different Roast Levels

Different coffee roasts will have varying blooms. For example, dark roasts (such as those Italian roasts) will contain less CO2 when compared to the exact same coffee roasted at… let’s say the Full City level. So depending on how dark your roast is will affect how much gas will be released during the bloom stage, makes sense?

Where The Beans Come From

The origin (where they were grown) of the whole coffee beans can also impact the bloom. Some coffee growing regions are known to have more out-gassing than other regions.

How Hard Are Your Beans?

The harder the coffee beans are the more difficult it will be for CO2 gases to escape and make it through the coffee bean.

Goose Neck Kettle for the best coffee bloomingTip: The get the best coffee bloom ideally you should be pouring your water over your coffee grounds in either a zig-zag or circular motion, this will help to evenly saturate all of the coffee grounds. To do this effectively I recommend using a Goose Neck Kettle such as the Hario Buono Coffee Drip Kettle or any kettle with long pouring spout.

To Bloom or Not to Bloom?

Yes, you most certainly want to bloom your coffee if possible. By adding in just enough water to moisten the freshly ground coffee (rule of thumb: 2 grams of water to 1 gram of coffee) will allow for the CO2 to escape which will vastly improve the taste of your cup and it will show you just how fresh your coffee beans actually are.

Depending on your coffee maker the coffee bloom process will be slightly different, keep on reading and I’ll briefly cover how to bloom coffee in a French Press, pour overs such as the Chemex, and Automatic Drip Brewers (yes you can bloom coffee in those too).

coffee bloom

How to Coffee Bloom?

As I’ve already covered to bloom coffee involves pouring just water over freshly ground coffee beans to allow for the gases to escape. However, the process does vary slightly depending on what type of coffee brewer you are using. Let’s take a look at the common three coffee makers.

How to Coffee Bloom with a French Press

If you are not sure of the brewing basics make sure you check out my article How to use a French Press first, before you get ahead of yourself and start worrying about the coffee bloom.

If you already know how to use a French Press, simply pour you water over your coarsely ground coffee beans. Remember to pour just enough water to soak the coffee grounds, think of a wet sand consistency or about 2-parts water to 1-part coffee.

Depending on just how fresh your coffee is you should start to notice a bubbling bloom forming on top of the water. Stand back and let the bloom remain for 15-20 seconds whilst waiting you can admire the awesomeness and take in the smells, once done slowly stir the coffee bloom. String will ensure that all of the coffee grounds become fully saturated with water.

Once stirred continue with the pour and your normal French Press routine, depending on how strong you like your coffee leave the French Press steeping for up to 4 or 5-minutes.

Pour Overs and Coffee Blooms

The coffee bloom process is slightly different when using a Chemex pour over, or any pour over method for that matter. To start the bloom process, slowly pour your hot water (not boiling) over your freshly ground coffee beans, in a circular motion starting from the outside and then slowly working your way into the middle.

The trick is to use just enough water so that the coffee grounds are saturated and uniformly soaked but they don’t become too wet that coffee starts to drip through the filter. Let the coffee bloom for roughly 60-seconds if you are using a Chemex. Once the bloom has finished continue with the pour and your regular “pour over” routine.

Coffee Bloom Using Automatic Drip Coffee Makers (yes it’s possible)

If you are still using a drip coffee maker you obviously haven’t spent too much time reading through this website and have yet to venture into the world of manual coffee brewing. Hey that’s okay, but I strongly suggest that you ditch those push button coffee makers and find out what your missing with manual brewing.

To coffee bloom using a drip coffee maker first begin by placing a filter into your basket (I would recommend using a Gold Tone filter) also make sure to check out my article Permanent Coffee Filter vs. Paper for more tips. Next add your freshly ground coffee beans and then pour in just enough water to soak the grounds, just like the Chemex you want to saturate the coffee but not too much, you don’t want the water to start dripping through the filter.

You should now start to see the bubbling coffee bloom at this stage, wait for a minute to a minute and a half, then simply operate the drip coffee maker as you normally would. If you bloom your coffee before your regular brewing cycle you will notice that the water will form an even pool on top of the coffee grounds rather than the few drip depressions. This even pool of water will allow for a more even extraction and a ultimately a better tasting cup.

coffee disclosure This article may contain affiliate links on some of the products I use and recommend. Clicking on an affiliate link won’t increase the cost for you but makes it possible to identify the referral by this site. So if you find my article beneficial and decide to purchase via my links I will get a small amount of commission which I can put towards some coffee (probably not enough for a lobster dinner though). Read my full affiliate disclosure here.
Mark (Bean Ground Admin)

Mark is the guy brewing up Bean Ground. He likes to think of himself as a bit of a coffee fanatic who can never get enough coffee! You'll often find him in a caffeine induced rant talking about... you guessed it, coffee.

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