Thirty-two Christmases ago, Anchor Brewing Company owner Fritz Maytag made 300 cases of a limited-edition beer and gave the bottles away as gifts. “I knew of the ancient tradition of little brewers in various villages creating a special holiday ale and giving it to friends and family,” says Maytag. “I thought it was just such a lovely idea.” Since then, Anchor has put out one-of-a-kind Christmas beer with a different tree on the label every year—beech, birch, redwood, Douglas fir, even palm—but the spices and formula for the beer itself remain a secret.

It’s believed that Mexico’s malty dark amber Noche Buena was the first North American Christmas ale marketed for sale to the public, appearing in 1938, but Anchor is considered the longest-running Christmas ale producer in the United States. In the years since Anchor pioneered the trend stateside, scores of brewers across the country have created their own seasonal beers. Holiday ales now account for 12.5 percent of total yearly craft-beer sales, according to the Brewers Association, and are the most rapidly growing piece of the microbrew industry. Even mainstream breweries have gotten in on the act. This year, Miller offered a chocolate lager for the holidays, and Anheuser-Busch made three holiday brews, including a Vanilla Oak beer.

Outside America, centuries-old traditions still dictate styles of holiday ale. In Belgium, Christmas beers are generally dark, high gravity (strong), and somewhat spicy, though most of the time the flavor comes from malts and hops rather than actual spices, like cinnamon or cloves. Norway produces more Christmas beer than any other country, with the oldest brewery, Ringnes, churning out over half a million liters a day. The typical Norwegian Christmas beer is a nutty, coppery lager that’s light to medium bodied and unspiced, but Scandinavia also produces winter ales brewed with actual spruce tips. As expected, they inflect a slightly pine tree–like flavor. Spruce has been used throughout the Northern Hemisphere (it was historically favored by seamen, who believed it could cure scurvy), but these days finding a spruce beer is harder than you’d think. Oregon’s Siletz Brewing Company Spruce Ale and Alaskan Brewing Company’s Winter Ale are among the few that make it stateside.

Spruce was historically favored by seamen, who believed it could cure scurvy.

There’s no one way to make holiday beer. Some brewers (like Maytag) spice them. Some (like Sierra Nevada founder Ken Grossman and Goose Island brewmaster Greg Hall) believe that beer is no place for spices and instead create spicy flavors that taste more like what you’d expect from beer, by dry-hopping (adding hops to the maturation tank to increase pleasantly bitter, citrusy, and piney flavors and aroma) and by using caramelized and/or chocolate malts. (Caramelized malts result when barley malts’ starches are converted to sugars and caramelized by a specific dry-roasting technique. Chocolate malts have been roasted to a very dark stage, where chocolate-like flavors come through.)

The fact that holiday brews are unique, change yearly, and are available for a limited time has spawned a collectors’ market. At the Chicago bar Delilah’s, owner Mike Miller holds an annual Christmas-ale tasting, where he and his customers sample beers from years past. At the same time, many beer geeks age their holiday brews, like wine. “Christmas beers are generally darker and stronger, so they’re pretty much built for aging, plus you can learn something by seeing how a beer changes over the years, how it takes on winey qualities, how the beer comes into balance,” Miller says. “I have six vintages of Anchor, eight of Sierra. I have King & Barnes Christmas from ‘95 to ‘99 and they ceased to exist in 2003. I still have the Belgian Fantome from ‘98 that people go crazy for.”

Anchor’s Fritz Maytag does the same. “At any given moment, I’ll have four or five different years from my private stock stashed in the refrigerator, and each night before bed, my wife and I share one,” he says.

Just don’t forget to brush your teeth, Fritz.