WLP029 fermenting cold?

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Sep 11, 2021
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I am a relatively new homebrewer, brewing extract without temperature controls (all-grain and a chest freezer are planned future investments, but working for now with what I have).

I love lagers, and recently brewed a nice altbier-ish beer using WLP029 (White Labs Kölsch/German Ale yeast) which I think had some nice lager-ish smoothness. The ambient temperature was probably in the mid- to high 60s during fermentation.

Two days ago I brewed a similar recipe with the same yeast, but here in the San Francisco area we are in the middle of a cold snap and the ambient temp. in the closet where my carboy sits is now in the mid-50s and I don't expect the temperature to increase much over the next week or two. It's been about 40 hours and I'm seeing the beginnings of fermentation, but it's very slow.

I've done some research on here and I read that this yeast can sometimes stall if it gets much below 58 degrees.

What do you guys think? Should I:

1) Buy some lager yeast and make a starter, and pitch that in the next couple of days (given that I expect the temps to stay within lager range)? I have never repitched a second yeast after fermentation has begun, much less pitching a lager yeast on top of an ale yeast. Any downsides, here? I don't have a way to cold-condition the beer after fermentation, except in the fridge after bottling - could I still produce a good beer this way?

2) Just give the kölsch yeast some time to do its work and hope for the best?

3) Unknown third option?

Can you move the carboy to another room that's closer to 60 degrees? Pitching another yeast could give pretty unpredictable results so I would avoid it.
If it seems to be fermenting I would let it go. wlp029 is usually pretty quick when used in the mid to upper 60s, being in the 50s it may take a bit longer. If you can do something to boost the temp that would not be a bad thing.

Seedling mats or a ferm-wrap will get you a few degrees warmer and up into normal ale temperatures.

Long term if you come up some sort of temp control you will have greater success or at least more consistent results.

edit: added a missing not
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I would keep it at the same cold temp until it's ~50% of the way to expected termnal gravity or it starts to visually stall then move it to a warmer location to finish.
Thanks all for your input! I will leave it then, for now, as stuff seems to be happening, and will see about warming it up a bit if I can to help it finish out.
I agree with @Bilsch - if it's going to stall it will be when it gets towards the end of fermentation. Leaving it sit for now, then move later is best. You've got the hard part underway with signs of fermentation. It will progress more slowly, so maybe in a weeks' time the weather will have warmed and you don't even have to do anything fancy.

Another easy option for temperature is to wrap it in a sleeping bag or some heavy insulation of some sort. Fermentation creates heat. Not a lot if you're way at the lower bounds of a yeast's capability, but if you keep that heat trapped in, it can help buffer you from any cooler temperature swings.
Not only does it stall at those temps I got a clove flavor and have been using 2565 ever since. Pitched 18 gal at 58* on 12/31 and will raise it to 64* tomorrow to finish.