How to Lager
Andy Chambers, Home Brew Expert
It’s cold and miserable outside. But one thing about this time of year keeps me excited; brewing lagers! A lager is a beer that has been fermented and stored at cold temperatures. Lager styles range from highly drinkable and refreshing pilsners to filling and warming dopplebocks. This article will cover the processes involved in brewing a lager at home.
The first step for making a lager is making sure you have enough yeast. Lagers require much more yeast than ales do. Either use multiple packs of dry yeast or do a multi-step yeast starter to attain the yeast count needed. O’Connor’s HBS has an article that explains the steps needed for a yeast starter if you are not familiar with the process.
The second step is obtaining wort. Whether you use extract or all grain brewing methods does not matter at this point. When chilling wort try to bring the temperature as far down as possible to fermenting temperature. I have read articles that suggest beginning fermentation at ale temperatures to give the yeast a good start, but I have personally never tried this method.
The third step for making a lager is maintaining fermentation temperature. Most lager yeasts require temperatures around 55ºF or lower- depending on the yeast strain. This initial fermentation will last for about two weeks. The best and easiest way to maintain this temperature is to create a fermentation chamber. Typically these are made out of old refrigerators or freezers. I have seen a few made with foam insulation and window air conditioning units as well. If you are only brewing lagers then you only need a cold side temperature controller. If you plan on brewing ales as well, a two-stage controller is best. A two stage controller will require both a cold source (refrigerator) and a heat source (small heaters work well). I don’t have the space or money for a fermentation chamber, so I have to rely on old mother nature and my creaky drafty home to keep my attic a constant 50 degrees Fahrenheit. It has worked fairly well so far, but I can only brew lagers in winter.
The next step is the diacetyl rest. Many lager strains produce an off flavor called diacetyl during normal cold fermentation. To counteract this off flavor, increase fermentation temperature to 68ºF for two days. I do my diacetyl rest when my gravity reaches the last five points of fermentation. The timeline for this can vary widely. I have had beers take anywhere from 5 days to just over two weeks to reach its final five or so points. It definitely help to check the gravity fairly often (every 3 days or so).
Now its time for the big step: lagering. Move your beer into a secondary container and turn your fermentation chamber to 35ºF. Some people choose to stagger their temperatures and slowly bring the temperature down to 35ºF. I have never noticed a difference in doing this. Don’t have a fermentation chamber? No problem, just find the coldest place you can possibly can where the beer won’t freeze. I just put my carboy into my kegorator and forget about it. The beer should sit for a minimum of two weeks, but preferably longer. I let my Oktoberfest/Marzen lager sit for over 3 months. Although this is a lot shorter than a traditional Marzen, it still tasted amazing.
Final step. Take a deep breath. Whew. It’s been at least a month of waiting for your delicious beer. Now all you have to do is keg or bottle it. If kegging, simply keg the beer as you normally would. Bottling, however, requires an extra step. Because you have spent so much time letting the yeast crash out, you need to add bottling yeast to ensure that you get proper carbonation in your beer. This is especially important if you aged for a long time. I prefer to use CBC-1 bottling yeast. It is cheap and easy to use. After 2 weeks in the bottles crack and enjoy.
In short the fermentation schedule should look something like this:
2 weeks at 55ºF in primary fermenter
2 day diacetyl rest at 68ºF
2 weeks (minimum) lagering at 35ºF
Bottle or Keg