Primary Fermentation

Looking for more information about primary fermentation? This is the definitive post to answer the questions of what it is and how long it should last.

Definition of Primary Fermentation

We define primary fermentation as the process of introducing a fermenting microbe to your wort or must until its process is complete or interrupted/merged with a second process.

How Long Should Primary Fermentation Last?

For homebrewing beer, the length of time for fermentation can vary.  If you are a beginner homebrewer and you are brewing an ale that doesn’t have a high starting gravity (less than 1.070) from a recipe kit, you should let your primary fermentation last 2 weeks. Just leave the beer in your primary fermentor for 14 days as a good rule of thumb.

There may be recipe kits out there that have instructions to only ferment the beer for 1 week and then bottle.  For example, when we started homebrewing over ten years ago – we followed recipe instructions from our local homebrew shop kits that had the one week fermentation step.

Over the years, the two week standard has served us well. Again, this is a good guideline for most ales that you brew when you first start out homebrewing.

Here are some points to keep in mind:

  • A fermentation duration of two weeks is not a rule. It could take shorter or it could take longer. The duration is determined by many factors including the yeast (strain, health, and count), your wort, and the temperature.

The best way to know that your fermentation is done is to take a gravity reading to see if your beer has fermented to its target final gravity.

Get tips on how to take gravity readings during fermentation!

  • In our experience, two weeks is better than one; we have had better results with two weeks than one. It gives the yeast more time to reprocess some of the early stage fermentation byproducts and time for the yeast to settle out.
  • Keeping your beer in one fermentation vessel for two weeks and then bottling or kegging is ideal. By skipping a secondary vessel conditioning phase, you are eliminating a chance for contamination. Also, we are of the opinion that conditioning most ales in a secondary vessel provides little to no flavor enhancements to the final beer that you can get from bottle or keg conditioning.

Follow this link to read more about secondary fermentation and when to skip the step.

  • We feel that secondary vessels should be used for high gravity beers, for lagering, for beers that are going to have post-fermentation additives (dry hopping, fruit, spices), and for beers that call for the addition of a second microorganism intended to feast on sugars that the primary strain does not.  You should use them for certain techniques or beer styles.  The point is, for most ales, a two week primary fermentation is all you need.

Primary Fermentation

Hopefully, this post has helped you out.  Please leave a comment below if you have a specific question for us to answer.  Brew on.

Comments

  1. I’ve seen some materials that recommend 3 days, some that says 7, some that says 10 to 14…

    I personally leave it alone for the first two weeks and then take a reading. If I need to do aging I’ll transfer it all into a 5 gallon secondary, or I’ll keg it up.

    But, anything less then 7 days seems to leave too much sugar in solution and gives me bottle bombs, or gives me off flavors that usually improve with some additional time in the bottle or keg. Waiting two weeks seems to take care of a lot of this for me.

  2. I think the prevailing wisdom has changed relatively recently. It was believed that fermentation should last not much longer than a week because of yeast autolysis.

    Autolysis apparently isn’t a real threat as Palmer and Jamil Z recommend primary of two weeks up to a month and now Secondaries are generally thought of as a bad thing.

    Apparently moving beer to a secondary after a week, really cuts short their cycle. During the extra time they are able to do a lot of work cleaning up the beer.

    This all sounds great to me, as it’s easier and the risk of contamination is lower.

  3. Thank Chris and Dave for posting your thoughts.

    Question: If the notion is that process of creating a secondary fermentation is a bad thang, would you still do one if you were going to add some ingredients for flavor, like fruit or spices? Recipes generally instruct to introduce these additives in the secondary fermentation stage. If you didn’t create a secondary fermentation stage, would you add these ingredients towards the end of the primary stage?

  4. First of all… I’m definitely a newbie, so don’t take my word for it.

    Some of those extras can be added right to the keg. If you’re not kegging sometimes they can go right in the bottling bucket. You can even dry hop right to the keg.

    But… I think everyone would say, there are times that racking to a secondary makes sense. Lots of fruit, maybe high gravity, I’m sure there are some other good scenarios. What I was saying is, a lot of times it’s not neccesary and it’s my understanding that when you do do it, you want to do it after a couple of weeks to allow the yeast to do their thing. When you rack to a secondary, you’re losing a lot of yeast. So, I would say if there is a situation to that you want to do a secondary. Give it a couple of weeks in the primary first.

  5. When I first started brewing I would only primary ferment for 1 week. I found that after a few week s in the bottle I would get overcarbed beer. Obviously the beer was not fully attenuated. I then decided to start fermenting at least 2 weeks and sometime 3-4 weeks for bigger beers and definitely 4+ weeks for lagers.

    As far as a secondary I have done it mostly when adding flavor or dry hopping, but I see no reason why this could not be done in the primary after the majority of fermentation is complete.

  6. Hi Dave,

    That’s what I was thinking. Only do a secondary fermentation if the beer absolutely needs it. If you are going to do something different like add ingredients to modify flavor, then do a secondary fermentation and just be really careful because you are opening up the chance for contamination.

    Hi Todd,

    I think that I would opt not to add flavor ingredients into the primary vessel. If I am going to open up the primary vessel to the elements to add something, I might as well get the beer off the yeast cake.

    The only way to figure this out is to experiment. Use both methods and compare results.

  7. Experimentation is what homebrewing is all about. Learning to make something better is a crucial part of that.

    I have generally always fermented my beers for two weeks in primary. Mainly out of laziness actually. Then I rack to a keg to condition cold and carbonate. I find a lot of merit in the idea of fermenting two weeks, based on what many have already stated regarding letting yeast go through their entire life cycle. At least two weeks gets you there for sure in most cases.

    Autolysis I think is another one of those held over homebrewing concerns from years past when most people used dried yeasts that were several years old. The yeast we have these days is in much better health that it ever was in the early days of brewing. My best evidence for autolysis not being a problem came last winter. I brewed a batch of IPA and Porter. I brewed them up and never got back to them for 4 months!!!! When I finally kegged them carbed them and tasted them they were still good beers depsite sitting on the yeast cakes for so long. They were stored cold (winter garage temps) so that likely helped, but there was no autolysis flavors to note or be concerned with. Healthy great yeast can get through their whole life cycle and then go perfectly dormant in the right conidtions.

    Secondary fermentation has always been a misnomer. There is rarely any fermentation going on there. It should really be considered, IMO, as a conditioning step. I only employ a “secondary” when I hav a high gravity beer that I know isn’t done fermenting, but I want it off the bulk of the yeast cake. In that case it really isn’t a second ferment, just a continuation of the first. The other time I do secondary is when I want to add fruit or spices. I don’t do that in the keg normally, because its hard to get beer out of a get with fruit in there too.

  8. Thanks guys for this discussion. I have just finished brewing my first IPA, was wondering about timing for 1st & 2nd fermentation. Now you guys have answered some of my questions.

  9. Glad we could help with your fermentation questions. Let us know if you have any more.

  10. That depends on your style. English brewing books almost always recommend changing over to a second fermentor after you reach 1/2 way to your FG. In most cases, for english style ale, thats about 3-4 days. It helps clear up the ale in the end (drop bright) and it also helps the flavor to get it off the trub. A secondary fermentor (or dropping) goes until its basically almost stopped bubbling or approached your final gravity. Then you need to mature (IE cask condition) the ale for another 3 weeks. That final step seriously makes the ale. Bottling just doesnt cut it when you have had dry hopped cask ale.

    It’s interesting how the Brits scream to do it this way, and only this way, yet we tell people in this country to leave their ale in the primary for 14 days or more! My ale has always ended up outsanding using the brit methods and i really cant see leaving it on the yeast for that long, in primary.

    But once again, it depends on your style.

  11. Maybe this is an opportunity for an experiment. We can brew an English Pale Ale, split the wort into two different fermentors, and follow two different fermentation schedules.

    If we do that, we can share the results.

  12. Great updates all, thanks for the input.

    I’m a new brewer. On my fourth batch at the moment, ended other beers WAY too early in the past (had a porter I bottled after 1 week with dry malt and corn sugar as a primer…. literal bombs and foam. I would have liked to have seen what Mentos could’ve done there.)

    Anyway, I am working on an IPA right now. Have made a few faults on it so far, pitched the yeast in a rush at a wayyy too high temperature, didn’t sterilize the oak chips well… etc. So, despite the costs, I’ve considered this another experimental beer to see what factors I can control and see what flavours I get with and without faults.

    I let my fermentation go for over a week in a primary container and have just switched it into a glass carboy for the thought that I would be doing myself a favour in avoiding yeast autolysis and allowing the yeast to settle. After reading everything that everyone has had to say, I think I’ve made a mistake now in doing that.

    Any serious ramifications? I don’t worry much about contamination… I’m quite cleanly and haven’t had many problems before. I think the main thing is that I realize now that the beer was nowhere near calming down fermentation and that it’s now going to continue for a while.

    Is it fine to stay in the carboy (out of light, obviously) indefinitely? Should I stop fiddling around with it like a petulant child faffing with Christmas presents under the tree?

    Ah beer, a culture long repressed by the mass producers is returning to the people!

    It’s a good cultivation, thanks all for the involvement and the effort.

    Cheers.

  13. Jordan,

    Yes, stop fiddling. Leave it in your carboy for another week to 10 days. You should be ok.

    I think the reason why the experts say to skip the secondary is to limit your chances of contamination.

  14. I’ve had one in the primary for 3 weeks now, and it’s still bubbling. The OG was 1.072 and today it read 1.020, I’ll check it again in a few days. I am seriously thinking about skipping the secondary on this one, but I am undecided right now. You’d think a month in the primary would be enough, but who knows…

  15. I think it largely depends on the situation.

    What yeast are you using? English Ale = shorter time, Brett = months or years of conditioning/fermenting..probably not primary though.

    Is this a high gravity beer?

    What is the fermentation temp? Cooler = Slower

    I usually let stuff sit, because, I can’t get around to it. On the other hand I’ve made a couple English Ales from wort to keg in a little over a week due to party deadlines.

  16. Is this new conventional wisdom of 2 weeks standard for all styles? I have a Witbier in the carboy, Saturday will make the end of week 1, and I really don’t have the time to bottle on Sat… Thinking about letting it sit until Monday (I have the day off) what say you?

  17. Hi Bryon,

    For your particular situation, I think you will be ok if you let it sit an extra day or two.

    Two weeks is just a guideline. I created this post because the two week guideline went against my own conventional wisdom of fermentation only taking a week for ales.

    I left my APA in the primary for two weeks…and it came out well. Mike’s opinion is that it’s the best beer I’ve brewed to date and I agree with him.

  18. Byron:
    Relax. Have a homebrew. ;-)
    3 days is certainly not going to kill it.

  19. RY, I certainly will relax, but all I have in stock is my left over holiday ale, not so great for this nice Spring weather…

    John, I concur, tomorrow (Monday) shall be bottling day!

    I really want to get one or two of those party pigs to make life easier, until I build up to kegging though… http://www.partypig.com/ Anyone ever try those things?

  20. I am confused after reading all the different posts. I just did a red ale last night, and was told to rack to a secondary when the air lock is only doing 1 to 3 bubbles a minute. This is only my second batch. So my question is, do I need to rack to a secondary, or should I leave it in the primary for two weeks or more and then bottle.

    Any help would be great.

  21. The party pig is cool, but they cost like $50 for one. You need 2 or more for a full 5 gallons. You can get a basic kegging system for about $150 and can expand it as you grow.

  22. Danny,

    For your red ale, I would leave it in the primary fermenter for 2 weeks and bottle.

    We feel that secondary vessels should be used for high gravity beers, for lagering, and for beers that are going to have additives (fruit, dry hopping).

    Unless your red ale fits into the above categories, just ferment it in the primary for two weeks and then rack it up.

  23. Thanks for your reply! My last question, is how long should I leave it bottled for?

    Thanks again!

  24. For this beer, I would store the bottles out of direct light at the same temperatures that your yeast needs for optimal fermentation for another two weeks.

    You can open one or two earlier, just to check on things or just to collect information about the young beer’s taste, aroma, appearance, etc. but I think the beer will be really good after two weeks of bottle conditioning.

  25. Hey all,

    I’ve got a friend who had done a few batches this fall, and he and I am starting again for the summer, here in two weeks.

    We have a couple 5gal ball-lock kegs, we were going to use for secondary, conditioning, filtering and serving. And I just wanted to get this straight.

    If we are conditioning, filtering and serving from a keg (and thus also doing a touch of force carbonation), does this sound like a good step by step (assuming clenlieness, no aration, and priming transfer kegs with CO2 to avoid oxidation):

    1. Primary ferment for 1.5-3 weeks.
    2. Transfer to keg and condition/flavor for 1-2 weeks.
    – – I had a thought here, should I transfer in a touch of the cake to provide yeast for the secondary? Or will there be enough yeast in the solution to continue fermentation with any priming sugars in the secondary keg?
    3. Rack and filter to Tertiary keg for forced carbonation for 1 week.
    4. Drop pressure and serve.

    Al transfers done in a closed system. The stopper of the primary fermenter has a gas release hose, as well as a permanent liquid hose. The first transfer works by connecting the liquid transfer hose to the liquid out nipple of a sterilized and primmed keg, and charging the primary fermenter with CO2 to transfer (forced transfer, not siphon). All other transfers would occur to primed kegs (CO2 displaced Oxygen) to prevent oxidation and aeration.

    Does this sound like a good plan? Or too over the top?

  26. Sounds like a nice closed system set up to keep O2 exposure real low. I think your steps are sound so I’ll add only a few comments.

    I routinely let my beers sit in primary for at least 2 weeks; most often it’s closer to 3 weeks. At that point I transfer right to a keg. There is always going to be plenty of yeast still in solution so I wouldn’t worry about that. You can call it a secondary fermenter, but all the sugars are gone and you aren’t going to get much more fermentation, of course unless you add priming sugars. But you say that you are going to force carbonate the beer, so I don’t quite see why you’d be adding priming sugar.
    I would just transfer the beer to the keg after primary, chill it, set the pressure for your forced carbonation process. Let is carb up for a week or two and condition in the cold. Then I’d draw pint to see if the carbonation and clarity is where you want it. If its good, then push that beer over to a fresh clean keg to leave the sedimented yeast behind.
    You’ll now be in that “tertiary” vessel with very little yeast and fully carbed ready to consume.
    Definitely not over the top. I’d just skip the priming sugar steps. That’s what kegging is all about.

    Brew ON!

  27. Richard says:

    my yeast did not start in the primary – wart may have been too warm. Suggestions? Add more yeast?

  28. If you have more yeast to add, you may want to add it.

    Next time you may want to try a yeast starter

  29. I usually do ~7 days of primary (until the foam has settled), then 14-20 days in secondary before bottling or kegging. When bottling another month is needed to achive desired carbination, but is worth the wait. Give your beer some time instead of bottling after a week after boiling. This is supposed to be about taste… the mass produced domestic lagers are there if you are in a hurry. Buy some more carboys, let it age, and enjoy patience.

  30. Hey all-

    Depending on the beer you are brewing, the risk of contamination isn’t really that big of a deal when going to a secondary. A belgian ale, for example, benefits greatly from a secondary, and by the time it’s siphoned it’s at 9-10 percent. This reduces the chance of contamination a lot. Generally speaking, the heavier the beer, the longer you want to keep it in both primary and secondary. It will benefit from a longer primary simply because it wil take longer for the yeast to do the job with the higher OG, and it will benefit from a longer secondary so you don’t end up with exploding bottles. Contamination isn’t as big of a deal as people think it is, as long as general cleanliness is followed. Look at Belgian monks: brewed delicious beer before they even knew what bacteria was. There’s nothing wrong with letting a heavy batch sit in primary for 3 weeks and seconday for a month. Don’t worry, there’s still pleny of yeasties left in there, and as long as you have a good ferm-lock and you havent exposed it a lot, you’ll be fine.

  31. Any chance of some advice?
    I’m just doing my first 2 brews, a coopers pale ale and a mexican cerveza, I started them both nearly a week ago and i hope to be battered for christmas!
    I got some (possibly duff??) advice to give them a stir so obviously they havent settled into a cake yet. Im not going to do a secondary fermentation because of time restraints and lack of any more buckets.
    How long should I ferment then for? and Should I leave them for longer in the primary and have them sat for less time in the bottle or should I bottle them early and have them resting for longer? Would filtering out some of the cloud when I bottle help?
    Any advice would be greatly appreciated because I havent got a scooby doo what im doing!
    Thanks Tom

  32. Hey Tom,

    If ‘giving them a stir’ means to open up the lid and stir them with a spoon, I would say, “Don’t do that.” You don’t want to risk contamination.

    Keep them in your primary bucket for another week. Bottle them after that. By my calculations, they will be in bottles for three weeks on Christmas. For these styles, your timing is spot on. They will be ready to be enjoyed on the 25th of December.

  33. When you say to ‘leave in the the primary’ for upwards of 2 to 3 weeks, you’re snapping down the lid and using a airlock, right? Just checking, as my primary is a solid lid, with no hole drilled for the bung.

    Thanks.

  34. Hey Mark.

    Yes, we mean snapping down the lid and using an airlock. You will need a way to let the CO2 escape if you are going to ferment a beer. I would look into retrofitting your fermentation vessel with either an airlock or a blow off tube.

    Brew On.

  35. Hi All!

    Great forum. This is my first post here.
    I have been struggling with this issue forever.
    My beer ingredients supplier tells me “never more than 5 days” but the fermentation is never over at 5 days and if i rack, it stops.
    So i leave it two weeks or more, until the fermentation slows down to 1 to 3 bubbling a minute in the air lock. Then most of the sugars are converted to alcohol.

    On the other hand, i am rarely completely satisfied with the taste of my beer and i think it has to do with autolysis and the fact that my beer stays for too long in contact with the dead yeast at the bottom of the primary fermenter.

    So it’s a dilemma. I don’t want to re-pitch the yeast after i rack as i don’t think this is standard procedure.

    My yeast seems healthy, my wort also, i have been brewing for more than 10 years.

    Still puzzled.
    Jimmy.

  36. I have a question for the Pro’s:
    I have a dunkelwizen kit, after one week in primary I moved to seconddary and I at the end of 7 days in secondary. The fermentation slows down to 1 to 3 bubbling a minute in the air lock at this time.
    My question is if I can keg it and force carbonate at this point?

  37. Go for it!

  38. I am a slacker – Here’s what I do.
    I have brewed hundreds of batches to support the consumption of a 4 piece band that plays 3x week. I’ve had excellent results with very quick turn around using the steps below, and I have never had a bad batch! Obviously each batch is different; for the most part I usually stay around a 12 pound grain bill and keep the two favorites in stock, a SN IPA clone and an catamount porter clone.
    I brew AG, depending on the batch I usually see rapid bubling to complete blow off occur within 45 minutes of pitching yeast. I use a yeast strain from my local brew pub owner, no idea on the specifics. Usually after 4-5 days I am down to 1 bubble every 1-2 minutes and a very low gravity. This point I transfer to a secondary glass 5 gallon carboy and let sit till it settles (usually about 3-4 days, when I can shine a flash light thru the beer and it’s consistent from top to bottom). At this point I move to my corney keg and crash at 28 degrees in the freezer for 24 hours. I crank the c02 to 30 PSI, lightly shake/roll on my lap for 100 seconds. You can hear the C02 disolve into the solution. Within a few hours I am drinking clear and fully carbed modertaly potent 5-7% beer that tastes as good as the store brand. Using all grain methods and hops grown in my backyard I only spend about 15-18 dollars a batch or 40 cents per pint. In the store we pay 1.50 for 12 oz bottles. I said earlier that I never had a bad batch. Well here’s the trick to recover from a bad batch. Get a 30 dollar reverse osmosis water filter kit from sears, run the bad batch through and out the other side guess what? Grain alcohol :) warning may cause short term disability – Have fun, don’t sweat the little stuff relax and have a pint!

  39. Brennon says:

    Seth,
    How the hell do you get rapid bubbling and blow off within 45 minutes of pitching yeast???? That is unheard of!

  40. I start the yeast the day before, rapid bubbling within 45 minutes. I have vidieo footage.

  41. tom zipp says:

    i have a batch in my primary now- its been a week and still getting 2 bubbles a miniute . never had it ferment this long befor i racked to a carboy – im getting nervouse !!

  42. Hey Tom Zipp. Let it ride. It’ll be ok.

  43. tom zipp says:

    just racked it to the carboy – bubbled 2/min

  44. I just bottled a 5 gallon batch of Enlish Brown ale after three days of fermentation at about 68 degrees F. Bubbles stopped appearing in the airlock and I decided it was time. I tasted the brew also and it was delicious but not carbonated. Is this normal? Do you think I got ahead of myself? I primed the brew with 5 oz of sugar before bottling. I’m a little worried I’m going to have exploding bottles on my hands. Thanks for all advice.

  45. Did you taste it out of the primary fermenter? If so, then it is normal that it wasn’t carbonated.

    If not, how long was it in the bottle? If only a few days, then yes…that’s normal. You should let it sit in the bottle for at least a week…if not two.

  46. Its been two weeks and a day, and my IPA has bubbles still coming out at about 2 per minute. first reading was 1.052 and now 1.015. The local beer store said it could have bacteria in it. What do you guys think.

  47. I tasted it from the primary fermenter. It’s been bottled for a few days now and I don’t think I’ll try it for another week at least. Keeping my fingers crossed that the bottles don’t explode…

  48. It’s been a week and the bottles haven’t exploded. I tried one and it’s not nearly carbonated enough. A potential problem I’ve just now realized is I may have “prepped” the yeast in warm water for too long before adding to the wort, thus leaving an amount of active yeast completely insufficient for proper carbonation. I’m hoping another week or two will do the trick. Comments appreciated.

  49. Wait another week. It takes about two weeks in the bottle to carb up fully. If they haven’t carbonated after another week, take your learnings and put into your next brewing session.

  50. I am brewing a batch of Dunkelweizen. It has been in the primary fermenter for 8 days now and the airlock has slowed down to about 1 bubble every 2.5 minutes. This is going to be the first batch that I ever keg with and don’t want to mess it up. Should I go ahead and keg, leave it in the primary, or transfer it to the secondary????

    Thanks,
    Dave

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