What Does Green Beer Mean in Brewing?

Find out what green beer means, all your questions answered from the experts at Brewpedia. (and no, it's not the colour)


Mat Stuckey

9/23/20233 min read

a glass of beer sitting on top of a wooden table
a glass of beer sitting on top of a wooden table

Think green beer is something you get on St. Patricks day? Think again. The term "green beer" actually refers to something important in the brewing process. Read on to learn all about green beer and beer maturation.

What is Green Beer?

In brewing terms, green beer is beer that has finished initial fermentation but still requires conditioning and maturation before it is ready to package and drink.

After the initial fermentation, green beer is often cloudy with active yeast still in suspension. It may be technically drinkable at this stage but green beer will usually have unwanted flavours like acetaldehyde or diacetyl present.

Green beer requires more time for the yeast to continue working and clean up off-flavours. This maturation process, which can take anywhere from a few days to many weeks depending on the style, allows green beer to fully develop into a polished, delicious final product.

So in essence, green beer is a beer midway through the brewing process - not quite unfinished but not yet complete either.

Why Beer Needs Maturation and Conditioning

Fermentation is fast - most yeast will chomp through fermentable sugars in just 4-7 days. But that doesn't mean the beer is ready yet! Here are some things that happen during conditioning and maturation:

  • Yeast cleans up off-flavours - Diacetyl and acetaldehyde get reabsorbed by the yeast as food sources.

  • Proteins and tannins settle - Particles drop out, clarifying the beer naturally.

  • Carbonation develops - CO2 dissolves back into the brew, carbonating the beer.

  • Alcohols smooth out - Harsh fusel alcohols become integrated in the overall flavour.

  • Flavours meld and mature - Ingredients marry and develop complex flavours.

Without proper maturation, beers would have quite poor flavour. Just as bread needs time to rise fully, beer takes time to finish conditioning.

Typical Maturation Times by Style

Maturation times vary widely depending on the style:

  • Pale ales - 7-10 days is common, promoting hop flavours.

  • IPAs - Often just 1-2 weeks to preserve fresh hoppiness.

  • Stouts - 4-8 weeks allows roasty flavours to smooth out.

  • Lagers - A long cold conditioning for 4-8 weeks (or more) is critical.

  • Sours - Tart beers may age for 6 months up to 3 years.

  • Barleywines - Big beers require months to years to fully develop.

So while light ales need just a week or two, bigger beers require much more patience and conditioning time.

What Happens During Maturation?

There are a few key things that occur as green beer matures in conditioning tanks:

Settling and Clarifying

As conditioning continues, proteins and tannins coagulate and settle out along with the heavy yeast, clarifying the beer naturally. Finings can help speed this process.


The remaining yeast consumes residual sugars still in the beer, producing CO2 that dissolves back into the brew. This natural refermentation carbonates the beer.

Off-Flavour Reduction

Compounds like diacetyl and acetaldehyde get reabsorbed by the yeast as a food source, reducing their presence and unpleasant flavours.

Alcohol Smoothing

Fusel alcohols become integrated, losing harshness. Ethanol and water combine for a fuller, smoother mouthfeel.

Flavour Blending

Ingredients marry over time, reaching a peak of complexity and balance. Hop flavours fade while malt develops.

How to Know When Beer is Ready

So how can you tell when green beer has finished that all-important maturation process? Here are some signs:

  • Clear, brilliant beer is free of cloudiness and sediment

  • Aroma is clean without off-odours like butter or green apples

  • Full carbonation gives a smooth, creamy mouthfeel

  • Flavours are harmonious, complex, and well-blended

  • The style's optimal alcohol warmth and body has developed

  • No yeasty or saccharine green flavours are present

With these indicators, brewers know their green beer has successfully matured into premium draft beer ready for serving.

Commercial Maturation Methods

For large breweries, various systems exist to provide efficient conditioning and maturation:

  • Uni-tanks - Combination fermentation and ageing tanks

  • Horizontal tanks - Oval tanks that reduce sedimentation time

  • Burton Union system - Interlinked casks allow yeast circulation

  • Lagering tunnels - Traditional cold ageing for crisp lagers

Homebrewers have the advantage of more easily monitoring small batches closely.

The Green Beer Myth

Of course, the idea of green beer has also become intertwined with St. Patrick's Day due to an odd tradition of dying beer green to celebrate, especially in the United States.

While this practice is harmless fun, true beer aficionados know that a beer's colour has no relation to its maturity or quality. One brewing myth debunked!

Green Beer: Wrapped Up

Hopefully this article has cleared up what precisely green beer is and how crucial proper conditioning is for brewing stellar beers. While it can be tempting to rush beer to serving, patience during maturation always pays off. So let your green beer finish its journey - only fully matured brews become great beers.

want more info on beer and homebrewing? Head over to the Brewpedia blog for more!