I started my first batch of home brew lager around 24hrs ago I aerarted it and it was at 20 Degrees celcius but does not appear to be fermenting..... I know people say I have to give it time as I read a lot of forums.

I took a hydrometer reading which was 1035 and will only open after 5 days to take another to see if fermented or not, Air locks are not bubling although I know this isn't a true sign

However it is in my shed wrapped up in one of my hooded tops to keep it warm and is at around 10 Degrees celcius.

So my question is can yeast function at this low temperature and if not any suggestions - I do not have a power socket for a heat belt in the shed so thats out of the question.

Any advise would be greatly appreciated.

Also if fermentation hasn't started after the 5 days do I justadd more yeast without aeraiting?


  • is this your first kit or just your first lager? Most lager kits ship with an ale yeast. Do the instructions say anything regarding fermentation temperature?
    – mdma
    Commented Aug 23, 2012 at 13:25
  • this is my first kit and first homebrew.... I'm a complete newby but I spent months researching about it and deciding whether to do it or not and have watched hundreds of youtube videos so do have some knowledge - maybe the yeast was not a lager yeast then! why would they provide the incorrect yeast it just doesn't make sence.... I just persumed yeast was perhaps old and dead.
    – up4fun2day
    Commented Aug 23, 2012 at 15:22
  • maybe ill get home after work tonight and it could be fermenting away, fingers crossed
    – up4fun2day
    Commented Aug 23, 2012 at 15:23
  • 1
    It's because most people don't have access to somewhere cold to ferment a lager, and because of the long ferment, hygiene is paramount. Since this is your first kit, I would continue with the ale yeast, and get a few brews under your belt before tackling the more difficult lager beer.
    – mdma
    Commented Aug 23, 2012 at 15:54
  • thanks for all the advise the yeast was slow acting and did ferment the lager took around 6 days to reach 1001 and tasted great which was better than expected at bottling kegging stage now to wait for carbonation and maturing to fully enjoy my brew
    – user2650
    Commented Aug 28, 2012 at 14:39

3 Answers 3


20C is 68F, which is normal-to-high ale temperature. Why do you think this is "low" for a lager? Lagers are typically fermented at about 50F, give or a take.

Also, I wouldn't wait 5 days. You don't have to check the gravity to see if fermentation has started, just take off the airlock and look down into the bucket/carboy through the opening. A clear, smooth surface mean that either fermentation hasn't started yet, or its totally done and the yeast has dropped, in which case there would be a ring of krausen/scum right above the liquid in the vessel. Either way, fermentation has a distinct smell that's "sharp", probably from escaping C02, so you can learn to tell if its underway from smell alone. If you are using a bucket, just put your nose right over the grommet and push down on the lid a little. This will force gas up to your nose and let you smell the wort without opening the lid.

Regardless, if its not fermenting within another 24 hours, then I'd question the viability of the yeast packet, and I'd probably pitch another to be safe. No need for further aeration.

  • I'll give it a smell tonight so if its a sharp smell its fermenting right???
    – up4fun2day
    Commented Aug 23, 2012 at 15:12
  • if it hasn't fermented and I need to pitch more yeast I just sprinkle it on top and is there any speciac type of yeast I should aim for as user below comented that there is lager and ale yeasts which I didn't realise I just used the one that came with the kit
    – up4fun2day
    Commented Aug 23, 2012 at 15:13
  • Don't just sprinkle the yeast on top of the wort. If you use dry yeast, rehydrate it before pitching by putting it in some warm water (95-105°F or 35-41°C) in a sanitized container. Warm water from the tap is probably fine, but to be safe, you can boil it first to kill any contaminants. Commented Sep 4, 2012 at 23:59
  • Meah, I've done both and never noticed a difference in lag time. Last batch a few days ago was sprinkled, it took right off. Basic Brewing Radio did a collaborative experiment and noticed no difference between rehydrating and sprinkling (albeit with a somewhat small sample size). I recommend new brewers to just sprinkle and focus their efforts in other places.
    – GHP
    Commented Sep 5, 2012 at 12:52

My guess is that you got an ale yeast with your kit, and 10C good for a lager yeast, but is far too cold for an ale yeast. You need to raise to at least 15C, ideally 16-17C. The way to know with certainty is to check the instructions that came with the kit. These will have advice on ideal fermentation temperature.

    – up4fun2day
    Commented Aug 23, 2012 at 15:16
  • kit I had was brewmaster original lager beer kit from UK - is there a specific name for lager yeast so that I buy the correct one? I will let you and the other user know how I get on thanks for both your help
    – up4fun2day
    Commented Aug 23, 2012 at 15:17
  • also if I heated it up how would you recomend doing this stand my bucket in a larger tub of hot water and would the heat not effect the lager as it should be brewed at low temperature...
    – up4fun2day
    Commented Aug 23, 2012 at 15:19
  • Is it this kit? brewuk.co.uk/store/beerkits/coopers/… These are designed to be fermented at room temperature - and as such they're not true lagers, but a pseudo-lager. Bring into the house if possible, somewhere around 16C.
    – mdma
    Commented Aug 23, 2012 at 15:24
  • no its 'brewmaker original lager beer kit' from the UK... Coopers is australian
    – up4fun2day
    Commented Aug 23, 2012 at 15:31

Also note that at lower temperatures, fermentation may not show up the way you would expect. I do agree though that you should be seeing something at 68F. I few degrees lower though and you might not, so thermometer error might skew things quite a bit.

You can try to add more yeast, or just let it sit for another few days and maybe take a hydro reading (I don't use a hydro though-- I go by taste).

You may also see about checking during the warmest part of the day or shortly thereafter. I would also suggest don't only look but smell. You may be able to smell the yeast and that is a good indication of fermentation.

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