March marks the end of winter and the beginning of spring, and this change of season is noticeable in many aspects of our daily lives, including what we consume. Of course, the world of beer is no exception. Thanks to the evolution of brewing and preservation techniques, it is now possible to enjoy any beer style at any time of year, but some traditions remain linked to the seasonality of beer, if only in name.

This is the case with meerts or bières de mars, as they are known in the French-speaking world. It is not a beer style in itself, but rather a variant or byproduct of lambics, one of the lesser-known gems of Belgian beer. While fame and recognition have always belonged to their older siblings, the gueuzes, bières de mars fulfilled their purpose for decades: to offer a refreshing, light, and affordable beverage, especially for the working classes of Belgian society.

A few years ago, its production plummeted to the point of near disappearance, but a young brewery in Wallonia is working to restore meerts to their former glory, even modernizing them to adapt to the new tastes of beer consumers.

But first of all, what is a lambic beer?

It is very likely that, when we talk about beer, the first image that comes to mind is that of a golden, crystal-clear beverage, served with a thick head of white foam and always at a very low temperature, almost frozen. And although it is true that a good portion of the beers consumed in the world fit more or less into that definition, there is much more to life than the classic industrial lager.

Currently, over 100 different beer styles are officially recognized, in addition to numerous local variations and several emerging sub-styles. Belgium clearly demonstrates its rich brewing tradition and history in these lists, with around 15 beer styles (as diverse as dubbel, oud bruin, witbier and saison) often considered to be of Belgian origin. Moreover, in 2016, Belgian beer and its culture were recognized by UNESCO as Intangible Cultural Heritage of Humanity, a clear demonstration of the importance this beverage has had in Belgium over the last few centuries.

One of these purely Belgian styles is lambic, a type of sour beer made with around 30% unmalted wheat and aged hops, used more for their preservative effect than for their bitterness or aroma. Its most distinctive feature is that fermentation occurs thanks to wild yeast strains from the Senne River valley and the Pajottenland region west of Brussels, where this unique beer style originated and where most traditional lambic breweries are located.

In order to brew lambic beer, after the mashing of grains and the boiling with hops, the wort is placed in koelschips, wide, shallow wooden or metal containers located in the brewery's attic. There, as it cools overnight, wild yeasts from the surrounding environment settle in the wort and initiate the spontaneous fermentation. The process continues in foudres, enormous oak barrels where the lambics evolve and mature for between six months and three years, or even longer.

The brewmaster's knowledge and experience are crucial in the lambic brewing process, as their palate determines the optimal time for bottling or blending. The market offers young (jonge/jeune) and old (oude/vieux) lambics; some macerated with fruit, like kriek with cherry or framboise with raspberry; others sweetened with sugar, like faro; and the most popular of all, gueuzes. These last ones are precise lambic blends from different vintages, combining the freshness and acidity of the more recent brews with the dry, aged and woody character of the older beers.

Despite their decline in past decades, lambic beers, and gueuzes in particular, enjoy a strong following and widespread appreciation not only in the local market but also internationally. They are enjoyed by Belgian families during celebrations and by beer enthusiasts worldwide, who seek out the most special and highly regarded varieties as soon as they become available, sometimes paying a fortune for a bottle of lambic. The cultural significance and local relevance of this beer style are evident every two years at the renowned Toer de Geuze, a weekend when lambic breweries in southwest Brussels open their doors to visitors from all corners of the globe, in what has become a true festival dedicated to gueuze.

Bière de mars, a historic product in decline

Historically, March has been an important month for European brewers. Taking advantage of the last cold days before the start of spring, in Germany, and more specifically in Bavaria, the märzen production season began. These malty, full-bodied beers were brewed before the heat of the warmer months encouraged bacterial contamination. Thanks to their high alcohol content and the presence of hops, they could mature and be stored throughout the summer, ready to be enjoyed at the typical Oktoberfest celebrations. And although it is not as well-known outside the beer world, Munich hosts the Starkbierfest in March, a festival focused on strong beers where styles like bock and doppelbock are tasted. But in Belgium, things work differently, and while other parts of Europe brewed powerful beers in March, Belgian brewmasters showed their rebellion with bières de mars.

These beers, also known as meerts in the Flemish region of the country, are simply a historical byproduct of lambic, brewed during the spring and summer months to quench thirst. After mashing the grain to produce the wort that will become lambic beer, the brewers wash and rinse the barley and wheat grains to extract as much of the sugar they contain as possible. This results in a second, less dense and sugary wort, which is then boiled with the hops already used in the lambic and fermented in the traditional way, yielding a smoother, lighter and less alcoholic beer.

Bières de mars are therefore an excellent example of the efficient use of raw materials and brewery resources. In addition to utilizing the last fermentable sugars present in the malt and giving hops a second life, the boil for the meerts wort is considerably longer (between 12 and 15 hours, compared to 4 to 6 hours for lambics), in order to allow the previously brewed lambic wort to cool properly in the koelschip, before its own cooling process begins. This efficient use of resources results in a more tannic and astringent beer, but also a lighter, cheaper, and more refreshing one, making it ideal for combating the heat and quenching thirst, just what Belgian farmers needed during their long days working in the fields.

Thanks to its characteristics and low price, this younger sibling of lambics enjoyed popularity in the 19th and 20th centuries, especially among the working classes, who considered it a perfect table beer for everyday consumption. Bières de mars were distinguished in breweries' cellars by a unique symbol that identified their barrels, and they were often blended with lambics to produce faro beers. Their very low alcohol content, less than 3%, helped them take root in the popular imagination and collective memory of Belgians, as many enthusiasts were introduced to the world of beer drinking them when they were almost kids.

Its popularity spread to other countries like France and the United States, where some breweries also produced their own bières de mars, similar in concept but somewhat different from the historical Belgian recipes. However, despite its strong social roots, meerts suffered a significant decline in production and consumption during the second half of the 20th century, almost disappearing completely from the market, which was then seeking more intense beers. Today, only the historic Brouwerij Boon, one of the protagonists of the lambic revival in recent decades, maintains the production of this style through its Boon Meerts. This beer, with less than 3% alcohol, is not usually commercially available, but is occasionally served as a draft beer at various festivals and events.

Tilquin, the Walloon brewery that revived the meerts

Lambic beers were almost exclusively the domain of the Flemish Brabant province, in whose southwestern corner all of Belgium's lambic breweries were located. But all that changed thanks to Pierre Tilquin, a bioengineer with extensive experience in the brewing sector who had previously worked for renowned brands such as Huyghe, 3 Fonteinen and Cantillon. In 2009, he decided to launch his own brewing project, choosing the town of Rebecq-Rognon as its location, establishing the facilities just 200 meters from the Belgian linguistic border, already within the Walloon Brabant province.

But the brewery Pierre founded, which officially launched in 2011, is unlike most. Tilquin is considered a gueuzerie, as it does not produce its own wort, but rather blends and ages wort made by other breweries, such as Boon, Lindemans, Girardin and Cantillon. Nevertheless, it has mastered the art of blending and aging lambics, and today its beers are appreciated worldwide: it exports almost 75% of its production and boasts a relatively small but diverse collection of oak barrels, allowing it to create surprising combinations and blends.

In 2011, Gueuzerie Tilquin became the first lambic brewery to open its doors in 12 years, and has been a pioneer in many ways ever since. In addition to macerating its beers with a wide variety of fruits and unusual adjuncts, such as hibiscus and rhubarb, it was the first lambic brewery to can some of its beers, undoubtedly a risky step, but one that aligns with the latest trends in the brewing industry.

In this context, Tilquin decided to use the meerts brewed by Brouwerij Boon in some of its creations, not only revived this almost extinct beer sub-style but also reinterpreted it and breathed new life into it. Due to their profile, bières de mars are ideal for reducing the alcohol content in lambic blends and can be consumed just a month after brewing, and Tilquin knew how to capitalize on these advantages. Their first experiment with them was the Meerts Box #1, a series of nine beers based on a blend of 80% bière de mars and 20% of different two-year-old lambics, released in 2022. These beers were infused with fruits previously used for other purposes, such as mirabelle plums and a wide assortment of grape varieties.

Their success among enthusiasts and experts was immediate, and they quickly became cult beers, highly sought after and appreciated for their quality and originality. Consumer reception was so positive that two more editions of Meerts Box were produced in 2023 and 2025, replicating their initial success and experimenting with the flavors and aromas of new grape varieties, including those used in many of Europe's great wines. In this way, Tilquin has demonstrated that bières de mars are not a decadent byproduct of lambic, but rather have great potential for innovation, and the public continues to consume and value them.

Tips and pairings to enjoy the meerts

As we have seen, bières de mars are light, refreshing beers with a good balance between acidity and the wild touch so characteristic of lambics. To appreciate the nuances of their spontaneous fermentation, it is ideal to serve them between 6 and 10 °C, as excessive cold dampens the complexity of the wild yeasts, and heat makes the acidity more pronounced. They can be enjoyed in a flute, tulip, stange or tumbler glass, or even a white wine glass, but should be poured gently to create a fine head without abruptly breaking the bubbles, as these beers typically have a delicate natural carbonation. As for the lees and sediment at the bottom of the bottle, they can be poured along with the beer if a more rustic and cloudy texture is desired, or discarded if a clean and bright drink is preferred.

Lambics have nothing to envy in the finest wines, offering elegance and finesse that lend themselves to a wide range of pairings. Specifically, meerts can be reminiscent of a dry white wine or even champagne, with a pleasant acidity, subtle carbonation, dryness and notes of hay, leather and citrus. Like these wines, bières de mars can serve a dual purpose at the table: cleansing the palate between bites or enhancing delicate flavors. It can be an excellent accompaniment to goat cheeses, melting perfectly with its creamy acidity, or to more intense cheeses like Pont-l'Évêque, where the beer cuts through the fat, cleanses the palate and contrasts with its intensity. In both cases, the pairing is completed by serving it with toasted nuts such as almonds or hazelnuts.

Due to the subtlety of their aroma and flavor, the perfect pairing for bières de mars is seafood, such as oysters and clams, either plain or with a few drops of lemon, or baked white fish prepared with aromatic herbs or citrus fruits. In the latter case, the ideal accompaniment would be a bitter salad with arugula, endive or wild asparagus, vegetables that are difficult to pair with other types of beer. Also highly recommended is pairing bières de mars with lemon roast chicken or quail with wild herbs, dishes that highlight the "funky" nuances of the fermentation. And to complete the meal, fruit-infused bières de mars are surprisingly delicious when accompanied by desserts made with dark chocolate, as the contrast between the tart fruit and the cocoa is spectacular.

In a world of increasingly bold and extreme beers, the meerts offer a sip steeped in history that champions the elegance of lightness. They prove that you do not need a high ABV to have a compelling personality, being uncomplicated yet refreshing session beers. So, the next time you are looking for a simple beer that awakens your palate with a very drinkable acidity, give a try to this "second rinsing" from the Belgian brewmasters.