Lager yeast strains generally enjoy an optimum fermentation temperature range between 45-55 degrees F with some exceptions. The question we get frequently here at Midwest is; "What is the correct way to handle lager yeast and lager fermentation?" Everyone has their own technique and procedure based on their own experience. I believe in experience and encourage fellow brewers to discover what works best for them and their system. That said, here are a few suggestions that may work for you while you are getting your chops down.

Before the brewing process has begun it is a good idea to prepare your fermentation environment a few days in advance to allow it a chance to stabilize. Let's say for example you are intending to ferment your lager at a temperature of 48 degrees F, dial that temperature in on your thermostat a couple days before you begin to allow your refrigerator a chance to stabilize at this temperature.

A yeast starter is a damn fine idea for your lager; a 2 L starter for 5 gallons of wort or a 4 L starter should be fine for 10 gallons of wort. Once the starter is made it can be rapidly chilled in an ice water bath and then transferred to the 48 degrees F environment to stabilize over night. The following day your lager yeast can be pitched into the starter vessel and returned to the 48 degrees F environment. You can either drain the liquid above the yeast congregation on the bottom and just pitch the sediment or go ahead and pitch liquid and all. Your starter should be at the peak of its fermentation cycle in 12-24 hrs and this would be the optimum time to use it. In other words you could begin brewing the next day.

The brew day-you have boiled and chilled the wort and have transferred it to the primary fermentation vessel. If you can, thoroughly aerate the wort before pitching the yeast. If you do not have an aeration system then a few minutes of vigorous shaking should be better than none at all. There are a few schools of thought on the next step and I leave it to you to determine which course of action to take. One, you can pitch the yeast starter into the primary and leave it at room temperature until you see signs of fermentation and then remove it to the controlled environment. Two, you can pitch the yeast into the primary and then immediately remove it to the controlled environment. Three, you can remove the primary to the controlled environment and let it stabilize for 24 hours before pitching the yeast. At home I go with option three and here's why.

With option one you are pitching a temperature stabilized, actively fermenting yeast culture into a considerably warmer environment. This can have the adverse affect of shocking the yeast, which results in an extended lag time. By time the yeast recovers from this and begins fermenting at the warmer temperature it is slung back into the cooler, correct temperature and again it is shocked. This can result in more lag time and worse, peculiar and unintended flavors turning up in the finished product.
With option two a similar adverse effect can happen. The wort is chilled, at least with most tap water driven chillers, to roughly between 65-75 degrees F depending on the season and the current groundwater temperature. This is quite a bit higher than the temperature the yeast starter had been stabilized at and shock, again, can come into play along with off and unintended flavors.

With option three the yeast is pitched into the environment it has already been fermenting in. Shock is eliminated and if properly executed very little to no lag time can be experienced. The only thing is that it tends to make people nervous about leaving their unfermented wort chilling overnight without yeast in it. If your sanitation technique is up to par and you are normally not plagued with infected batches of beer this method should prove quite effective when an adequate quantity of actively fermenting yeast is added. You should observe decreased lag time and decreased production of undesirable flavors.

Pitching sufficient quantities of yeast under the correct conditions should allow you to wrap up the primary fermentation in 10-21 days depending on the beer being brewed. The beer can then be transferred to the secondary and allowed to finish up another 7-14 days or so. When the beer is entirely finished fermenting it can be racked again and the temperature dropped to 33 degrees F. The laagering process has begun and can continue anywhere from two to three months.

If you want to bottle the beer before beginning the laagering process you can do so out of the secondary after a few weeks has passed and much of the yeast has settled to the bottom. In this case the fermentation temperature should be maintained, the beer primed and racked to the bottling bucket, and the bottling process carried out. The bottles are then returned to the fermentation temperature and allowed to condition until properly carbonated. This should take roughly two weeks but may take longer.

Once the desired carbonation level is achieved the temperature can be dropped to the laagering zone, 35-33 degrees F. Again the laagering can be maintained for 8-12 weeks.