How long do I need to control fermentation temps?

[zackattack784]

So I'm currently working on acquiring a chest freezer to make a fermentation chamber. The one I can get should hold 2 buckets. How long do I need to strictly control fermentation temps? The reason I ask is that in my house it routinely drops below 60 degrees in the winter and can exceed 80 in the summer. Depending on the beer I usually go a month before I bottle. Is it necessary to control temps the entire time or just until FG is reached? Right now I have 3 batches fermenting but if I should control temps the entire time I might need to cut back to two batches at a time.
Thanks!

 

[joshesmusica]

it's generally recommended to control temps throughout the duration of fermentation. but that doesn't mean you can't allow the temps to raise after the vigorous fermentation has subsided. a lot of people try to keep their fermenting beer in the 65F range during the first few days, then let it raise to about 70F until they bottle/keg it or cold crash it. Temp control isn't just about making sure it doesn't ferment too low or too high, but it's also about making sure you're not having large temperature swings. going from 63F up to 75F then back down to 65F can upset the little yeasties, and then they won't perform as well.

 

[RM-MN]

I agree that yeast don't like large temperature swings but it depends a lot on how quickly the temperature changes and at what stage of the fermentation it happens. You only need tight control for the first few days as the yeast are chowing on the easy sugars. Once the ferment slows you can let them warm up and as long as the temperature doesn't swing a great amount they will do fine. If they start to warm and then cool too rapidly before they have cleaned up they may go dormant on you and not finish the job.

Now, to the "how long do I need to control the temperature" question. It depends. It depends on the OG of the beer (higher OG takes longer) and the temperature of the ferment (colder takes longer) so giving a strict answer isn't possible but most of the low to mid OG beers will be beyond where they need the strict control in 3 to 4 days so I leave mine for a week just to be sure before I let them warm up.