With the rise in popularity of mixed-fermentation beers, 100-percent Brett beers, spontaneously fermented beers and Lambics, wild ales, sour ales and farmhouse beers, the terms that define these beers get tossed around more and more. Some of these terms are used interchangeably, and some people interpret them differently, adding confusion. To help you better understand their similarities and differences, I’ll attempt to explain all of them below.


This vague and broad category of beers can be summarized as beers fermented with more than one yeast strain – usually a strain of Saccharomyces ale yeast along with some strain of Brettanomyces (aka Brett) yeast. These beers may or may not be fermented with bacteria (i.e., Lactobacillus and/or Pediococcus). Oftentimes, mixed-fermentation beers are fermented with ale yeast during primary fermentation followed by Brett in the secondary, or when barrel aging or refermenting in bottles.

100% BRETT BEERS100brett

100-percent Brett beers are fermented with only Brettanomyces yeast (i.e., no Saccharomyces yeast). These beers may be made with just one strain or multiple strains of Brett (e.g., bruxellensis, lambicus, claussenii).

As an aside, Brettanomyces is Latin for “British fungus.” It was first classified in 1904 when the cause of spoilage in British ales was being investigated.


Spontaneously fermented beer is beer that has been naturally inoculated and fermented by wild yeast and bacteria in the air, rather than by pure or mixed cultures of yeast and/or bacteria. The most common way to make this beer is to pump the hot wort into a coolship, which is a wide, shallow and open tank, and allow it to cool overnight in the open air. This is when the wort is naturally inoculated by a mix of microorganisms (i.e., wild yeasts, including various strains of Saccharomyces and Brettanomyces, and bacteria, including Lactobacillus and Pediococcus – affectionately known as “bugs”) that happen to be floating around in the air. Usually, this method is only done in the cooler months, typically from late fall through early spring, when airborne microbes are most favorable.

Once cooled, the inoculated wort is usually pumped into oak barrels or foeders, where it picks up even more microorganisms residing in the wooden staves that were left behind from previous batches. This “straight” / “unblended” beer is often aged for months or years, and over time it will become funkier and more acidic.

Many U.S. breweries have begun making spontaneously fermented beers, including Russian River, Allagash, Jolly Pumpkin, Midnight Sun, Jester King, de Garde, and more.

Coolship at the Cantillon Brewery in Brussels, Belgium.

Coolship at the Cantillon Brewery in Brussels, Belgium.

Lambic is a spontaneously fermented beer brewed in Brussels and the Pajottenland region / Senne Valley of Belgium. “Lambic” is an appellation of beers from a specific region in Belgium, similar to “Champagne” in France. Lambic derivatives make up a variety of styles with different characteristics: old or young, straight/unblended or a blend of old and young (gueuze), carbonated or flat, fruited (e.g., framboise, kriek, peche) or unfruited, and sweetened (faro) or unsweetened. It’s a category that’s steeped in history, employing certain techniques (i.e., turbid mashing followed by a long kettle boil) and ingredients (malted barley and unmalted wheat plus aged hops), and tied to a specific region.

One could certainly brew a delicious Lambic-style beer anywhere in the world (and many breweries do), but duplicating flavors derived from Belgium’s local microflora and the terroir of the old Lambic breweries would be impossible. And, of course, beers brewed outside of that region in Belgium shouldn’t be called Lambic.

Some breweries, however, do name beers in this vein with a respectful nod to Lambics, such as Russian River Brewing in Sonoma County, California, which makes a beer called Sonambic (a combination of Sonoma and Lambic). Perhaps one day a Bellingham brewery will make a Bellinghambic.


Generally speaking, wild beers are fermented with one or more types of Brettanomyces yeast strains, and they may or may not include Saccharomyces yeast as well. Some are sour and some are not.

The term wild comes from the fact that these yeasts truly flourish in the wild. They’re all around us in the air. Brett strains – even “wrangled,” cultured and isolated strains of Brett – are also much less predictable than pure, cultured strains of Saccharomyces.

Some people believe wild beers should contain 100-percent spontaneously fermented beer (or at least a portion of spontaneously fermented beer) in order to be truly wild, but many “wild” beers produced today are actually inoculated with cultures of Brett yeast, which provide brewers with more control and consistency.

Beyond being fermented with Brett, some define wild beers on a more philosophical level. “The character of wild beers arises not so much from the ingredients, but from the environment of the brewery: the air, the walls, the wood, and the casks,” says Jeff Sparrow, in his book Wild Brews. “A unique combination of environmental conditions (winemakers call this terroir) present in every place where beer is produced determines the character of a wild beer.”

Sour lovers: The 4th Annual SourFest is July 30. Get your tickets here: https://www.eventbrite.com/e/4th-annual-bellingham-sourfest-tickets-25821159784

Sour lovers: The 4th Annual SourFest is July 30. Get your tickets here: http://www.eventbrite.com/e/4th-annual-bellingham-sourfest-tickets-25821159784


Sour ale is not a style. It’s a broad category of acidic (low pH) beers that offer tangy and tart flavors.

“Sour ale” is more of an American term than a European one, although some imports now use the term on labels and marketing. Sour beer styles include Berliner Weisse, Gose, Flanders Red / Brown, some saisons, various fruit beers made with Lacto and/or Pedio bacteria, Lambic / Gueuze and spontaneously fermented beers, and more.

Some sour ales are fermented with Brett and some are not.


Some people believe that farmhouse beers should come from actual farmhouse breweries that are on actual farms. Most, however, do not take the term so strictly and literally.

Historically speaking, farmhouse beers were rustic ales from farmhouse breweries (aka estate breweries) in Belgium and France. Traditional farmhouse styles include Saison, Grisette, and Bière de Garde. Nowadays, these styles are loosely interpreted and they can vary quite a bit.

Farmhouse beers can range from relatively clean tasting to very funky (i.e., Bretty notes of barnyard, leather, horse sweat, etc.). Many farmhouse beers have some sort of connection to the land, and they sometimes feature local ingredients grown onsite or close to the brewery.Atwood

In the last decade, farmhouse beers have become wildly popular with American craft brewers. Recently opened Atwood Ales in Blaine, which is a true farmhouse brewery, is a great local example. Owner/brewer Josh Smith is embracing these styles of beer, and he’s making some of the best versions I have ever tasted.

If the rumor is true that Ron Extract and Amber Watts of Jester King Brewery plan to set up a farmhouse brewery in Skagit County, then we’ll have yet another excellent farmhouse brewery close to home.

As I’ve said many times before, it’s good to be a beer lover in the Bellingham area these days.