Which temperature do I ferment at: the recipe's temp or the yeast's recommended temp?

Question

So, I'm trying to brew a Mexican lager today. What I've done is taken Palmer's Cold But Not Baroque recipe and tweaked it a bit. However, instead of using Bohemian lager yeast, as the recipe calls for, I'm using WLP940.

Palmer's recipe calls for fermenting at 45°F (and then secondary at 35°F). However, according to White Labs, the optimum fermentation temperature is between 50°F and 55°F.

Should I be following the recipe's temperature or the yeast's optimum temperature? What about secondary fermentation temperature?

Answer 1

Those temps are close enough together that it really doesn't make much difference which you choose. If I had to choose, though, I'd go with the recipe. The temps recommended by yeast manufacturers are very approximate and often too high.

Answer 2

I just kicked a keg of Helles fermented with WLP940, great yeast! I pitched at 46°F and let it ramp up to 48°F for primary. I used this quick lager method and the beer was fantastic just 3 weeks later.