Can You Add More Yeast To Fermentation?

Wanting To Add More Yeast To This WineAfter the wine is done fermenting and it sits for a few days can I add more yeast and sugar to increase the alcohol level?

Name: Dennis
State: Missouri
Hello Dennis,

Once your wine has successfully fermented there is never any reason to add more yeast to the wine. The wine yeast you originally added at the beginning multiplies during the fermentation. If the fermentation went as it should, there should be about 100 to 150 times the amount of wine yeast you added, originally.

If the activity has stopped it does not mean that the yeast are dead. They have just gone dormant and are settling to the bottom. They ran out of sugar to consume, so they became inactive. When more sugar is added the yeast should pick up just fine on their own. There is absolutely no reason to add more yeast to the wine.

If you have racked the wine off the sediment this is still okay. There will still be plenty of wine yeast to get the fermentation up and running, again. Adding more yeast is not necessary.

Now that we have established that there is no reason to add more yeast to the wine, I would like to bring up a little twist that could put a wrench in the works.

There is a limit to how high of an alcohol level a wine yeast can produce. Most strains of wine yeast can make it up to 12% or 13% just fine. Some strains can even produce up to 16%, faithfully. But each strain of yeast does have its limits.

Shop Wine YeastThe point here being, is if you add more sugar than your wine yeast can handle, you could end up with a sweet wine – even one that is disgustingly sweet. It is important to understand this when making high alcohol wines.

So in summary, you can add more sugar to the wine to increase the alcohol level of the wine to a point, and to answer your specific question: Can you add more yeast to wine? There is absolutely no reason to do so, your wine will still have plenty of yeast in it.

Happy Winemaking,
Ed Kraus
Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.

39 thoughts on “Can You Add More Yeast To Fermentation?

  1. On day 7 of fermentation in my primary my P.A.=1(from12)now I would like to add the remaining sugar that I held back(feeding the sugar) to increase alcohol level……my question is…,should I get rid of the must or leave it in my primary? Should I add the sugar and put it in a carboy?
    Thanks in advance,
    Ron Boutet

  2. Ron, you need to rack the wine away off the sediment into another primary fermenter. Dissolve the sugar into the must. Once you see the fermentation is continuing (in a day or so) rack the wine into a carboy with an air-lock.

  3. My wine has been setting for about 8 days and is not fermenting like it should can I add more yeast and sauger to make it start back it’s setting in the apples what do I need to do???

    • Catfish, the first thing that you need to do is take a hydrometer reading to see if the fermentation is already complete and that is why you are not seeing any activity . If the reading indicates that it is not finished, you need to find out why it stopped before you can correct the situation. Adding more sugar is not the solution, that will just increase the alcohol content. The following article will go over the most common causes of fermentation failure.

      Reasons For Fermentation Failure

        • Do you need to stir the wine again after adding water the water to restart the fermentation? I have already added the finings and the mash is sat at the bottom 🤔

    • Thats not even 2 weeks so its fine not to see really any progress. Give it about ruffly 14 – 16 days then see, this is to say if u have been mixing your stuff daily.

  4. All that I’ve read makes sense and has been helpful, but when you go and tell me to take a hydrometer reading…this is life changing from English to Greek… I bought a hydrometer thinking that directions came with it…not!!..Sooooooo,I put it back into the wrapping and carefully stored it where it wouldn’t get broken. By God’s grace Iam making better wine than I’ve purchased in the store…for the most part; once in a while I have a batch with a little bite in it. Thanks for the emails.

    • Craig, we do hear from a lot of people that are not sure how to use the hydrometer. However, it is not as intimidating as it seems. Since your hydrometer did not come with instructions, you might want to take a look at the article posted below that explains the scales and how to use them.

      Getting To Know Your Hydrometer

  5. I have found adding more sugar seems best when added before all the original sugars are fermented. It doesn’t happen often but I’ve had a few batches over the years get stuck when I waited too long resulting in sweeter wine than I wanted.
    For about the last 5 years I add when the hydrometer reads between 1.005 and 1.010 and never had one get stuck since.
    Two words of CAUTION: 1. Don’t add more sugar then the yeasts alcohol profile can handle. I often use D-47 AND EC-1181, the D-47 can help develop a nice bouquet and the EC-1181 has a high alcohol tolerance. 2. If you add sugar before racking BE SURE there is plenty of room for expansion because it WILL foam quite a bit.
    FYI My ‘table wine’ for everyday consumption is SunCal Cabernet Sauvignon which averages 17-18% alcohol. To balance the high alcohol I use 3 cans to 12 gal. water, 2 oz. of acid blend gets my target of 3.5 ph. Yeast nutrient, energizer and tannin are per can recipe. I start with 25 lbs. sugar (OSG 1.105 [14% POTENTIAL ALCOHOL]) and add another 5lbs. @ 1.005.
    To finish the ‘balance’ I shoot for a final reading at end of fermentation of 1.010 for a semi-sweet wine with extra body and high alcohol. My daughters and I bottle in 1gal. jugs with loose caps with no re-fermentation problems.

  6. I put the yeast nutrient in after I put in my. Y yeast Will that affect My wine fermenting at a all this Is the first time I’ve ever used y yeast nutrient. Please help.

  7. My wine has been in a carboy for over 3 months. I did a hydrometer test and it never sank. Wine is really sweet. How do I get the yeast to start working again?

    • Jeff, if you are experiencing a stuck fermentation, the following article will go over the most common cause of fermentation failure. It could be a number of things causing this to occur such as the temperature. Before you correct the situation, you need to find out why it is stuck.

      Top Reasons For Fermentation Failure

  8. Hi ed I have made a batch of mead and has been fermenting for 4 weeks.It tastes Very carbonated and there is still bubbles coming to the surface and tastes quite strong in alcohol could it still be fermenting?I used bread yeast and have a hydrometer which I bought halfway through fermentation and don’t no the original reading. What should be my reading about please

    • Lee, if it tastes carbonated and there are still bubbles that tells me that it is still fermenting. When the fermentation is complete, the hydrometer specific gravity reading will be .998 or less.

  9. First time making wine from home grown grape. We rack it 3 times and it’s very clear now. But it sour but not like vinegar. Alcohol content less than 1 %. We only add 1 TBSP of sugar. I think we read the measuring sugar of must wrong. Can we add sugar right now? Or can we treat it like plain sour grape juice start all over again?

  10. I made a batch of wine with black currant a nd raspberries over half a year ago. It super sweet…not as bad as it was but srill way too sweet. Can i add yeast and start it up again? Alcohol level seems really low too.


    • Laura, if it is sweet, it did not finish fermenting. Before you can get the fermentation started again you need to find out what caused it to stop in the first place. The article posted below will discuss the most common caused of fermentation failure.

      Top Reasons For Fermentation Failure

  11. 16% is probably a safe statement and from what I’ve read trying to go too high from the beginning might slow or stall the fermentation. Almost always I start with a hydrometer reading telling me the potential is at least 15% and by the end of secondary the result is mostly 1% to 2% higher with the yeast that I use. The HOT taste is reduced by combination of More Fruit than called for, Ice in my glass and mostly by Aging.

  12. I have made a 5 gallon pail of Plum wine and it was fermenting for about 4 days, than it stopped, but i never added yeast. is it to late to add yeast now??

    • Jason, it is not too late to add wine yeast but first you need to destroy the wild yeast. Fortunately, there is a simple remedy for such a situation. Wild or natural yeast are not very resilient to sulfites, and sulfite is the active ingredient in Campden tablets, potassium metabisulfite and sodium metabisulfite. All you need to do is add a dose of any one of the above, and the wild yeast will easily be destroyed and no more natural fermentation. Wait 24 hours, then add a domesticated wine yeast to the juice. During this 24 hour period you should leave the grape juice uncovered, or at most, covered with no more than a thin towel. Shop Potassium BisulfiteThis will allow the sulfur to release as a gas and dissipate. Once the domesticated wine yeast has been added, you should see a renewed fermentation start within 24 to 36 hours.

  13. Hello Ed and everyone.
    I am attempting to make a 5 gallon batch
    ‘mixed’ plum wine and it is in the fermentation stage. It has stopped bubbling so I went on holiday and returned after 8 days believing it would be time for its second racking so I did a hydrometer test.
    The reading was 60 on the specific gravity scale which I believe equals approximately 10% alcohol. Ok I thought the hydrometer would have sang much more than this. It is also still cloudy but that is another issue so I have wrapped it again and added some pectalase.

    I am disappointed as it is ‘very’ sweet and only 10% alcohol. Is there anyway I can rectify this to achieve a higher alcohol volume or just leave it for a few more months and see what the outcome is.

    Many thanks

  14. Im new to home-brew but have recently made 2 x 7 day kits, one a White Pino , the second a Solomon Red Sauvignon blanc with Turbo Yeast 48 and 3kg extra sugar – I did not use the lid but a pair of tights so nothing could get in, kept them both warm. The white produced a lovely tasting but approx 10% creation, Initial fermentation seemed to conclude about 3 days, the red has produced %14 after 3 days, taste is perfect and obviously will last much longer, very happy.

  15. Restarting a stuck ferment – by accident

    I am not exactly a rookie but reading your posts have explained several of my stumbling blocks,, So I started a batch of white/blush wine, yeast is 1118, pot. alc. ..10% after two weeks I checked it at .990 and added two lbs of melted sugar, ferment stopped! after two week I transferred it to secondary and no significant ferment resumed, Sg at 1,50, stuck! , wasn’t overly sweet but not clearing either,, So I sterted adding bentonite to maybe help it clear and maybe salvage it, when I slowly added bentonite it started foaming, slowly added the five table spoons allowing the foam to lower as I added and stirred it. its working again, ferment is on day four and starting to slow. bentonite restarted the ferment! don’t understand why but not complainng.

  16. I have made my own homemade wine in a 5 gallon Poland Spring water bottle. I added 8 cans of Apple concentrate three packages of dry active yeast in 6 lb of sugar it’s been 2 weeks and still fermenting. But my question is I do not use an airlock I do not own an airlock I took a sterile surgical glove and taped it to the top it isn’t the size of a small balloon should that be sufficient if I do not have an airlock???

    • That can be a substitute with some success. What you have to watch out for it the glove shooting off the container and exposing your wine. Something else you can do when in a pinch such as yourself, is to simply stretch saran across the opening. Secure it with a rubberband then prick a tiny hole in it. Then, take a second piece of saran; prick a hole in it in a different location so the two holes don’t line up, and stretch it over the first piece and secure with a rubberband.

  17. Hi Ed,
    Following Catfish question above, i also have the same problem, my wine is on day 7 now and the first 3 days the activity was fine. I went to your “wine making reason for fermentation failure” i found that 1. the temperature in my room was either too cold at night and medium cold during the day, sometime i helped the activation by warming up the room with a heater. Day 5 all activity was gone. 2. I realised my wine was way too sweet, almost like syrup. I tried to fix this by adding more water but not Yeast. Now i have a huge batch of wine that i am so worried to toss out. Can i be able to fix this? Is it possible to restart the wine using the same batch and new yeast? Oh yes one last question, how long am i suppose to let it ferment for next time?

    • Fermentations vary dramatically in how long it takes to ferment. This is simply because if the conditions are not right, it can drag on for months. Conversely, I’ve had fermentations done in 3 days. Using a hydrometer to check the progress of the fermentation is the real key to knowing where you and your fermentation stands.

      Once you get the condition right based on the the Top Ten Reasons For Fermentation Failure, it will start fermenting again.

  18. Below i mentioned my wine recipe,
    1- 5kg grapes
    2-2.5kg sugar
    3- 2 liter water
    How much yeast aaded into this?

  19. Hello! I think I added waaaay too much sugar originally to my mango wine, the initial gravity reading was 1.132. I used Lavlin EC 1118 yeast for 4 litres of must. It seemed to ferment quite well for the last 30 days, the airlock happily bubbling steady, but eventually slowing. After 30 days the SG reading is 1.080. Why would the alcohol be so low after 30 days of fermenting? Have I just used way too much sugar?
    I decided to rack the wine today regardless. If I let it sit another 30 days will the alcohol level eventually creep up higher than beer? I see from the article that adding more yeast would be redundant?

  20. when making wine with a 28 day kit we totally forgot to add the yeast on day 1. it is now day 25 and the wine is clear but very sweet.

    can I add the yeast now will that give me a drier wine ?

    • Marion, I am not clear on if you ever added the yeast. If you did not, there was no fermentation and all you have is sweet juice, not wine, and you need to add the yeast to start the fermentation process and start all over again with the kit directions.

  21. Ok yeast is dormant or died. Was really alcoholic and little sweet ,now it’s more sweet I just racked it first time probably late, can I add more water to give more room for yeast to eat more sugar ie. Lower alcohol content to let yeast awaken and eat some sugar.

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