Fermenting Your First Lager  

Pilsner after about a month of lagering/being in keg fridge. No finings used.

Many brewers will at some point dream of making a perfect pilsner or other lager style, and many more will be apprehensive about straying from their reliable favourite ale yeasts. It doesn’t have to be daunting or even that different from fermenting ales. It might not be quite as fast as your ales, but it won’t be too much longer since we’ll be using an accelerated fermentation and maturation schedule. All told, you should easily have a nice looking beer on tap in 3 weeks, or bottle conditioned in 5 weeks (and there are always tricks when you’re in a rush!). I’ll break down a few topics below, and then give step by step instructions.

Brewing a Lager

  • Pick a style: Something in a normal gravity range, around 1.045-1.055 that you can brew well. With a lager, particularly the paler and simpler styles, any flaws in your brewing process will stand out more than in other recipes. Check out the Recipes section if you need some ideas.
  • Yeast: Use Fermentis W34/70 and plan to use 300 – 400 billion cells per 5 gallon batch (approximately twice what you would use in an ale). Pitching two packets is the easiest solution. Starters and repitching work great too, but that’s a whole new topic. In any case, don’t skimp on the yeast quantity! This is a workhorse strain used all over the world for production of many types of beers. There are many exciting strains to test out later, but for your first lagers W34/70 is like the trusty Swiss army knife of yeasts.
  • Temperature: W34/70 is not too picky about temperature. The results will be slightly different of course, but I have fermented using this yeast anywhere from 7 C to 20 C with good results. In this brulosophy article they tested this yeast up to 27 C, and made quality beer. The highest I have used it is about 20 C, so I won’t personally recommend anything higher, plus I think most of us can find a slightly cooler spot somewhere in our homes that will do.
  • Temperature control: A refrigerator with a temperature controller, or other type of fermentation chamber is ideal and is useful for ales in summer too. A cold cellar or unheated basement can work perfectly, as can swamp chillers and many other ideas. It is important to avoid swings in temperature — try placing your fermenter in a big tub of water if your location sees wide temperature swings. You’ll want to maintain a fermentation temperature between 12 – 15 C (as recommended by Fermentis, or up to 20 C), and eventually have a colder place for lagering around -1 C to 4 C.
  • Oxygen: Since you’ll be pitching twice as much yeast as when brewing an ale, it means there is half as much to go around for each yeast cell. Therefore, you should try to step up your aeration game a bit! The good news is that we’ll chill the wort colder than normal, which helps oxygen dissolve. For a lager of this gravity, using pure oxygen isn’t required, but certainly use it if it is available. Otherwise, just use good aeration techniques. This could include an aquarium pump and stone, shaking your carboy, using your wort chiller like a whisk, pouring the wort between kettle and brew bucket, etc. Aerate it more than you normally would — it isn’t possible to overdo it.

STEP BY STEP

  1. Make your wort, however you normally would. Nothing changes until chilling.
  2. Depending on your water temperature, you might only be able to reach about 15 C with your wort chiller. Chill to 15 C (or a bit colder, if you can) before pitching your yeast. Even if you are fermenting at 18 C, it is good practice to pitch the yeast colder and let the temperature free rise. In the heat of summer, you may need to use a fridge to cool your wort the last bit.
  3. Prepare your yeast. Recently, Fermentis changed the instructions on the packet and it now just say to “sprinkle into wort”… I’ve tried it and it surely did work, though professionals still recommend rehydrating. I guess if you can follow the directions and temperatures well, rehydrate it (otherwise skip this step). If using a cold crashed starter or harvested yeast, pour off the beer and let it warm up a little.
  4. Transfer the beer to your fermenter and aerate it thoroughly.
  5. Pitch your yeast and let the beer ferment at a steady fermentation temperature in your fermentation chamber, cellar or wherever you’ll store it until it is nearly done. Again, temperature is ideally 12 – 15 C but up to 20 C is fine. This will take a few days.
    This is a visual of when I start the diacetyl rest- notice that the krauesen has dropped significantly. I don’t open the fermenter and take a hydrometer sample- the key is to catch it while fermentation is still active, but nearly finished. With glass or clear plastic, we can accomplish that without risking contamination!
  6. Diacetyl rest or D-rest. The timing of the D-rest is sometimes recommended as around 5 gravity points away from terminal gravity (e.g. If your beer is expected to reach 1.010, the D-rest is ideally started at 1.015). If you are able to see your beer fermenting, I wouldn’t bother opening it up and pulling a hydrometer sample. Simply start the D-rest once you see the fermentation action slowing (the swirling action in the carboy has slowed, the krauesen thickness is decreasing/falling down, airlock bubbling has slowed… see photo).To conduct the D-rest, simply warm the beer up by a few degrees Celsius (or to room temperature) until it has completed fermentation. It should take a day or two, but it never hurts to give it extra time if you’re unsure.
  7. Your beer is now fully fermented and ready for lagering. You could essentially just cold crash it (with finings if you like) and treat it like an ale at this point. You should avoid extremely fast cold crashing, but just putting your fermenter into a fridge is fine. No need to do a slow cooling over a few days with this method. You could lager the beer for anywhere from a few days to a few months, depending on your preferences, but a couple of weeks in the cold will give good clarity. I’d recommend 2 – 14 days, and a temperature between -1 C and 4 C. You can always lager it some more after packaging.
  8. Package your beer. You can bottle condition or keg the beer as usual, after a period of lagering. No reason to do anything special. Sometimes people fear brilliantly clear lagers will not naturally carbonate well because they lack yeast, but adequate amounts of yeast remain. You can further lager the beer in the bottle. Once it has had time to carbonate (2-3 weeks), just put the bottles in the fridge for as long as they last. If you are kegging, don’t worry if the beer is still not perfectly clear. That will improve over the weeks spent in your keg fridge. As usual, the last pint is the best one.
  9. Enjoy! Even if you aren’t instantly obsessed, we can all appreciate a smooth, easy drinking pint in the heat of summer.
Nothing is quite as refreshing as a well brewed lager on a hot summer day. Cheers!

Footnote:

One thing to be aware of with cold crashing and lagering — oxygen. This can come from a few places: oxygen transferring through the walls of a brew bucket, entering the fermenter when you open it, or being sucked in through the airlock when the cold makes everything contract. As always, buckets aren’t recommended for long term storage, and you should avoid unnecessary opening of the fermenter. As for the airlock suck back problem, it is minor over the short term, but for extended lagering I would suggest a more ideal vessel like a keg, or a glass carboy with a solid stopper (oversized so it doesn’t suck in!). Note that with 3 piece airlocks the suction will draw out all the liquid from your airlock — the 1 piece S-shaped ones just bubble in reverse.

 

About Chris

chris

Chris has been brewing since 2012 and likes to make anything fermented. He studied Nutritional Sciences at University of Guelph and currently works for a gummy vitamin manufacturer. Other interests include distance running as well as DIY projects and cooking (and especially where the two meet, like building a smoker).