Lager 101: What You Need to Know Before Making Lagers

The term “lager”, like many brewing terms, comes from our German Brewing Brethren. It means “storeroom” or “warehouse”. They key reason behind the term is that lager, unlike ale, has a longer fermentation time which leads to a “cleaner” tasting beer than ales. Because the beer is so “clean” they are more difficult to hide any off-flavors in.

Attempting a lager beer before nailing a great ale is difficult but not impossible, however I would recommend having brewed many ales successfully and learning about off flavors before attempting lagers. You’ll have a better understanding of what can go wrong in the brewing process that causes off flavors and hopefully avoid them before investing a lengthy period waiting for your lager to be ready for tasting.

The Three Key Considerations for Lagering:

  1. Adjustable Temperature Control
  2. Healthy Lager Yeast
  3. Patience
fermentation chamber for lagerAdjustable Temperature Control: You need to be able to control the temperature of your lagering through a much larger range than fermenting an ale. An optimal range would be 35°F – 65°F but you could get away with bottoming out at 45°F. The lower the temperature, the more you’ll be able to clear out your beer, which will also help making it taste more “clean”.

There are many temperature controllers out on the market and a ton of different mods for building a fermentation chamber out of a fridge. The reason you need to have temperature control is because the yeast you’ll be using is a bottom fermenting yeast (lager yeast), and performs best at a cooler temperature. Throughout your lagering cycle you’ll need to adjust to different temperatures for different reasons.

Healthy Lager Yeast: I went into temperature control first because it’s the most difficult part to be prepared for when lagering. Without it, you’re just going to be making steam beers when using lager yeast. They are good in their own right, but since that’s not what you’re going for, then go build yourself a fermentation chamber and come back to this step when you’re done.

Now, I referenced above “bottom fermenting yeast” when talking about lager yeast. That’s an important concept to understand when lagering because it visually looks different when you have active fermentation as opposed to what you’re seeing in an ale yeast. Yes, you will get some krausen in a lager but nowhere near as much as ale. Do not fret when you see this. Lager yeast just prefer looking at beer from a different angle than ale yeast. At the bottom.

While it’s definitely important to have a good pitch rate for your lager, you can have success without using starters on lagers. There is some risk involved in that however, and you may have a stalled fermentation. It’s important to pitch yeast around the same temperature as the chilled wort to ensure you do not shock the yeast.

Lager yeast produces less esters and more sulfur than ale yeasts. Do not be concerned if you’re smelling rotten eggs in the beginning of your fermentation. This is common and will eventually go away while lagering. You most likely do not have an infected batch.

3. Patience: Many issues with lagering beer are overcome by ensuring you have a good fermentation throughout the lagering process. If you are not slowly easing your yeast through different temperature ranges you may find you’re not hitting the FG you’re looking for or potentially creating a lot of off flavors in your final product.

Personally I prefer making ales because I can test recipes more often due to a shorter fermentation. But if you want to test your quality assurance skills, and brew a new set of beer styles, then attempting a flawless lager could be in your near future. Here is a step-by-step rundown of a simple lagering process.

Basic Lagering Process

real wort starters

Starters on a stir plate

Day 1: Pitching your yeast, 65°F. Just like an ale you don’t want to shock your yeast. So pitch it and start fermenting around the same temperature your wort is after you chill it.

Day 2-4: Active Fermentation, slowly bring it down to 45°F. When you notice a good fermentation has started use your temperature controller to reduce the temperature to 45°F (or what your yeast package states) over the course of 2-3 days. Again, if you change the temperature too quickly you could shock the yeast and they may go dormant and you’ll lose your fermentation.

Day 4-14: Lagering, 45°F. Congrats, you’re doing it! At this stage you should be able to see fermentation continue but it won’t be as vigorous as it would with ales. While lager yeast do prefer a cooler temperature, they are also slower than ale yeasts at the temperature they prefer to ferment at. Depending on the beer you’re brewing it may be longer than a 2 week primary lager period so you should consult other lager recipes based on what you’re making. You can also check by taking a gravity reading. At this point you’re not looking for a complete fermentation but something around three-quarters of the way done is good.

Day 15-16: Diacetyl Rest, 65°F. Just like an ale, lagers produce diacetyl via science. That’s as far as I’m getting into that in this article. This is not a flavor you want in a lager. It’s very clear if you skipped this step in the end product because it is so clean. Don’t skip this step!

Additionally, just like in all the other steps, take your time when raising the temperature. The yeast is still munching away at sugars and you want the fermentation to continue after your rest. That continued process also helps balance out your diacetyl, again, this is through science.

Day 17: Secondary, 65°F. Before you finish lagering you should rack your beer into a secondary fermenter, off of the bulk of sediment. This helps to produce a cleaner beer. Once it’s in the secondary shove that bad boy back into your fermentation chamber. Be sure to avoid oxygenating your wort during the transfer. Purge the second vessel with CO2 if you can.

Day 17-18: Final lager, 35°F-45°F. Slowly reduce the temperature to continue lagering your beer.

6 Weeks: Lager @ 35°F-45°F. Yea, it’s going to take awhile to get this beer in your mouth so you should probably brew some ales in the meantime. Depending on your ability to get the temperature down and what the yeast you’re using can handle, drop the temperature as close to 35°F as you can.

Last 3 days: Cold crash @ 33°F. One of the things you’ll notice in most lagers is how clean and bright they are. Much of the yeast and other particles should have settled out of the beer by now, but a cold crash will ensure you get a clean and bright beer. And really, what’s a couple days going to hurt after 2 months?

lager beer 101

Finish: Package to your preference. Keg or bottle. If bottling some people add a little yeast slurry back into the bottling pale along with priming sugar. I usually keg mine to avoid the need for this but you may find it’s useful.

by Frank Lockwood
Frank works as a Group Director of Experience Design in the advertising industry. When he’s not building mobile apps and websites he’s usually thinking, drinking, making something to do with beer. Luckily, his wife loves to cook and drink beer, so many of the beers he brews usually have some type of ingredient you’d find in your kitchen. Molasses in his ambers, celery root in his Rauchbier and mustard seeds in his stout. He can also brew the classics and has done so to win homebrew awards and collaboration brews with breweries from 4 of the 5 boroughs in NYC. Carpe cervisiam!

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