Is there a simple rule of thumb for OG and fermentation time?

Question

I just brewed my 5th batch, but for the first time didn't use a kit, but an online recipe. So now, I have no idea of how long to keep it in the fermenter before bottling. From what I understand, a higher OG beer needs more time to age, but how much more? Is there some simple rule of thumb, or formula?

In case it matters, I made a Great Divide Yeti Imperial Stout Clone. I made it with extract, and missed the OG by a lot. The reading was 1.072 instead of the expected 1.090. I made another beer which had the same OG, and did 1 month primary, 2 months secondary and 3 weeks in bottles. That worked quite well, so I am inclined to stick to the same timeline.

Answer 1

There really aren't any rules that can be applied - too many factors come into the time it takes for fermentation to complete:

• OG
• Mash temp (fermentable vs. unfermentable sugars)
• Ambient temp
• Amount of yeast pitched
• Age/health of yeast
• Phase of the moon

Ok the last one's tongue-in-cheek, but you get the idea. The best way to tell if your ferment is done is with your hydrometer. When you're close to your expected final gravity and the readings are steady for a few in a row, bottle away.

That's not to say leaving it a month in the primary is a bad thing. I tend to leave my beers 2-4 weeks before even bothering to take a hydrometer reading. The yeast has plenty of time to finish what they're doing and have a nice flocculation.

A big beer tends to want to age longer after primary fermentation to mellow out the flavors; I notice especially strong alcohol heat mellows nicely with age.