Source:  Happybeertime.com

Not too long ago when you would order "a" Sam Adams beer at a bar or restaurant, you got a simple Sam Adams beer. It's amazing how many varieties of beer Boston Beer (SAM -1.06%) has now made available. This 30 year-old brewer is growing so fast on a percentage basis, it's almost making a mockery out of its larger rivals such as Molson Coors Brewing (TAP -0.53%).

The bubbling-over results
On Feb. 25, Boston Beer reported fiscal fourth-quarter results. Sales jumped 34% to $205.4 million, while earnings per share popped 6.4% to $1.33. Earnings would have been even higher except that Boston Beer is plowing money toward "advertising, promotional and selling expense and customer program and incentive costs" for its current brands and the ones it's about to launch.

Chairman Jim Koch Source: Boston Globe

Chairman Jim Koch attributes the continued sales growth to "innovation and variety" that has excited Boston Beer's drinkers. Koch stated, "During the first quarter, we are releasing several new beers that should continue this momentum." Test marketing of the new brews has given Boston Beer expectations that they will be smash hits.

Taps running dry
Boston Beer was a victim of its own success throughout 2013. Demand has grown so fast that the company literally can't brew the beer fast enough. Having more demand than supply is a great problem to have. The stresses on the supply chains have temporarily made costs higher than they should be, but this also allows Boston Beer to pass on any increased input costs to consumers. For example, it's raising prices 2% next year for exactly that reason.

CEO Martin Roper offers relief. He stated, "We improved our service level to our distributors during the fourth quarter and decreased our product shortages. In preparation for 2014, we have significantly increased our packaging and shipping capabilities, and our tank capacity at our [b]reweries." Expect your local bar or restaurant to be restocked once again; unless demand continues to surge once at the pace it's been going.

Big beer
Compare Boston Beer to Molson Coors. Molson Coors reported its latest quarterly results on Feb. 13. Sales ticked back 0.3% to $1.03 billion while earnings per share nipped down 0.2% to $0.68. Though the sales are still five times the size of Boston Beer, Molson Coors' growth is a yawner.

Analysts expect more yawns from Molson Coors this year and next. Molson Coors is expected to show sales growth of just 0.2% and 1.9%, respectively. Molson Coors trades at a P/E of around of 14 times estimated 2014 earnings.

Meanwhile, Constellation Brands (STZ 0.74%), like Boston Beer, is no slacker. While most of its exploding sales results lately are simply due to acquisitions, several of its specific beer brands are growing quickly. Last quarter, Constellation Brands saw its Corona Extra pop 6%, its Modelo Especial brand

Source: Beer Street Journal

 jumped 18%, and its draft business leaped 30%. The company plans to launch Corona Light draft and predicts that it will be its biggest draft product of them all. Constellation Brands trades at a P/E of around 21 times estimated calendar 2014 earnings.

Foolish final thoughts
It's hard not to love the growth numbers out of Boston Beer. Currently it trades at a P/E of around 35 to 40 times estimated 2014 earnings. But analysts don't seem to be pricing much in for the price hike, further tank-capacity expansion, and the success of the new brands. Cautious Fools should keep a close eye on Boston Beer and look for clues on how the new beers are doing; or consider getting in on the next sharp pullback should one return. Getting in on the 30 P/E ratio level may prove to be a great long-term reward.