A Beginner’s Guide to Lagering

Eventually in every home brewer’s career, they hit a point when they grow tired of brewing only ales and want to try their hand at brewing lager. Unfortunately, challenges with temperature control can make this difficult, but the key to successfully brewing lager is simply knowing when it is okay to cheat, and when you have to be a stickler.

The Big Cheat

Before we actually bite off lager brewing, let me say that it is OK for you to cheat when brewing lager and use a clean-fermenting ale yeast. While this is technically not brewing a lager, you can make some very good lager-style beers this way without having to bite off any of the temperature control issues we will be discussing in this article.

To brew a great “hybrid” lager, I’d recommend using one of the following yeast strains: White Labs WLP001, Wyeast 1056 or SafAle US-05. It’s also important to ferment as cool as you can within the range of the yeast you choose. However, don’t get too cold, as you’ll drop your yeast out of suspension and stall your fermentation.

Once the fermentation is complete, rack or bottle it and then refrigerate it. It will continue to “lager” in its packaging, mellowing out some of the flavors. If done well, the average beer drinker will not be able to tell the difference between this beer and a proper lager.

But then again, this is cheating. So, let’s discuss how to make a lager the right way.

The 3 Stages of Lagering

In a lager fermentation, there are three stages, and knowing these stages can help you understand why we do certain things when making a lager beer. The three stages are as follows:

1. Primary Fermentation:

This is the main fermentation process, in which the bulk of the sugars are broken down into CO2 and alcohol. This can be a fast and dirty fermentation, as when a brewer starts the temperature warms and then cools the beer, or is can be slow and clean. If you pitch with the temperature low and then keep it there, your beer will take a lot longer to ferment, but will not need as long in the maturation stage.

2. Maturation:

Maturation is also known as the diacetyl rest. In this stage, the yeast is allowed to clean up after itself, breaking down some of the more common off-flavors of lagers, such as the butterscotch-like diacetyl and the green apple flavor of acetaldehyde.

3. Lagering:

Also known as “Cold Stabilization”, this is the actual cold storage of fermentation in which lagering gets its name. In this phase, the haze-inducing proteins and polyphenols coagulate and fall to the bottom of your fermenter as cold break. This phase also mellows the flavors of the beer.

These three phases can be separated by distinct lines in the fermentation schedule or they can just flow into one another without any major changes to the fermentation temperature. Some brewers, for instance, prefer to raise the temperature of their beer somewhat for the diacetyl rest, while other prefer to maintain a cold temperature throughout the process.

How to Ferment Your First Lager

First, make sure you have a good starter. Choose a good lager yeast and make at least a 2 qt. starter for it.

Make sure the starter is aerated well, and pitch in a 5 gallon dose of healthy yeast (dry, Wyeast smack pack, or White Labs vial, for instance).

Side note: If you prefer to pitch the yeast cold, which is how the pros do it, you will need a larger starter. A starter as large as 1 gallon is common. The method of lagering in this post utilizes a “warm start”. Part of the benefit of pitching warm is rapid yeast reproduction up front. If pitching cold, you should also expect a longer lag time before krausen forms.

For your starter, don’t worry about fermenting cold. Your starter won’t be able to provide a significant amount of any off flavor, so you don’t have to worry here. Keep the starter fermenting at around 68-70° and let it go for at least a full day before pitching.

If you prefer, you can start it two days before, and, after a day, stick it in the fridge to precipitate the yeast to the bottom. Then, you can pour off the top part before pitching the sludge in the bottom of your starter into your wort.

Since this is your first lager, start with a recipe that has a moderate original gravity (around 1.056 or less). Not having a high alcohol content makes the fermentation a bit more forgiving, as the alcohol levels do not become detrimental to the yeast.

Once you have brewed the wort, chill it to 60°F for pitching. If your tap water cannot get the wort this cold, you may have to utilize an ice water bath or a pump to recirculate ice water through your immersion chiller to get the temperature down. By recirculating the cold water rather than the beer, you do not necessarily need a food grade pump. Just be sure to check that your chiller doesn’t have any leaks first. If you don’t have a pump, you can simply use an ice water bath or refrigerator to get the temperature down, but be sure to cover it while you wait.

When transferring your wort, make sure to leave as much trub as possible behind. While the effects of trub on fermentation is commonly debated online, most brewers will tell you having an excess of it in a lager fermentation may cause off flavors.

Remember: your beer will sit on whatever gets moved into your primary for about 4 weeks.

At this point, you can pitch the whole starter into it, or you can decant the liquid off the top and pitch the sludge at the bottom. If you did the big starter, I recommend just pitching the sludge, as your starter will significantly affect the volume of wort you have.

Wait until you see some fermentation activity before you move it to the cool spot you have cleared out for it. Once you see some bubbling or krausen, you can move it to any area that has an ambient temperature of 48-52° F. You may have a basement room in your house that is good for this.

In the warmer months, you may need to utilize a fridge or some trickery (there are plenty of low budget options for controlling your fermentation temperature), but in the Winter, you can even get away with just lagering in your garage, as long as the door stays shut. My garage makes some pretty good lagers in December and January.

Let the primary fermentation go for 3-4 weeks until there is no airlock activity left. Then, rack the beer to a lagering vessel. This can be another fermenter or a spare keg. Place it in a colder environment (32-38°F) for at least 4 weeks.

Once the final aging period is completed, you can rack to a keg and force carbonate or you can bottle condition. If bottle conditioning, you’ll probably want to add ¼-½ packet of fresh yeast. As the bulk of fermentation is already completed, you can bottle condition at room temperature without fear of off flavors. You can even use an ale yeast if you like. The flavor profile of the beer was determined in the 7-8 weeks of aging, so the yeast you use should not contribute anything to the flavor profile.

Diacetyl Rests

A note on diacetyl rests: One of the larger problems with homebrewing lagers is the maturation cycle. If you chill your beer too fast for the lagering phase, you can sometimes arrest the ability of the yeast to complete the consumption of diacetyl and acetaldehyde. To prevent this, a lot of homebrewers use a diacetyl rest. To perform a diacetyl rest, go ahead and rack your beer to secondary as described above, and then allow the temperature of the beer to raise to 55-60° F for 24-48 hours before chilling it back down for the lagering period.

This process “wakes” the yeast up and allows it to finish its work before the long cold lagering period. When using the “warm” pitching method listed above (60°F), this can be especially important.

There are a lot of great ways to brew fantastic lagers without going over the top on budget. This method is simply a good way to step into lager fermentations without overthinking it. If you decide to use this method to brew your first lager, drop us a line and let us know. We’d love to hear about your experiences, what you learned, and what others can do to prevent themselves from making the same mistakes.