Ask Mr. Wizard

How long to secondary ferment


Phil Kinney • Delaware, Ohio asks,

I brewed an imperial stout, and after the primary fermentation was complete, probably a month ago, I racked the stout into the secondary. And there it remains. I got so busy with other things I kind of forgot it in the corner of my wife’s kitchen. I do not want to discard it. The airlock is still in place, and there are still small bubbles rising to the top. Will I need to do anything different than the normal priming and bottling?



Many beers, especially big beers such as imperial stouts, mellow with extended aging in the secondary fermenter. It is usually best to place the secondary in a cool place for extended aging to prevent excessive yeast autolysis and to stunt the growth of bacteria that may be slowly growing and contributing funky flavors to your beer.

Your beer has only been in the corner of the kitchen for a month, so it probably is still okay. The best thing to do before considering discarding a brew is to take a sample of the beer and taste it. If it tastes like good beer, then continue to the next step and don’t worry too much.

Depending on the type of yeast you used and the temperature of your wife’s kitchen, the beer may have very little yeast left in suspension. Visual inspection in a very thin glass will give some insight into how much yeast is suspended in the beer. Another point to keep in mind is that the yeast that is in solution may not be in great health. If the beer seems extremely clear or if you feel the yeast may be cranky, you may want to add some yeast to ensure proper carbonation.

The actual amount of yeast required for conditioning is extremely small, about one-tenth the amount required for pitching. Although I recommend using liquid yeast for pitching wort when possible, dry yeast works very well for bottle conditioning. Let’s face it, all you really want the yeast to do is to cough out a little carbon dioxide and then sink to the bottom and keep quiet! As long as you choose a brewing-quality dry yeast, you’ll be fine.

When using dry yeast it is always best to hydrate the yeast in boiled and cooled water before use. The easiest way to measure out a very small quantity of yeast into your bottling carboy is to hydrate a whole pack of brewing yeast in a known volume of water; eight ounces works well. Then use about one ounce (about two tablespoons) of the slurry per five gallons of beer for conditioning purposes.

If you decide to go to these measures to ensure proper carbonation, be sure to mix the yeast slurry and priming sugars evenly in the beer prior to bottling. If the beer still tastes good on bottling day, your unintentional neglect shouldn’t cause any future problems.

Response by Ashton Lewis.