Please help me identify why my fermentations are stuck!

I made 6 batches of wine (sloe, blackberry, blackcurrant etc) of a gallon each. I started them all 6-9 months ago and after fermentation that was initially encouraging things slowed right down to the point where the SG was dropping by a couple of points per month. SG levels are still sitting at 1.030-1.050 and although I want a sweet wine 1.030 is still too sweet.

I racked all wines for the first time (thought maybe the yeast was getting old - don't know if this is logical) and decided to innoculate it with fresh re-start yeast hoping this would get things going again so I mixed half wine with half warm boiled water but fermentation remains painfully slow.

So what is the cause of this? I have eliminated a number of possible causes:
temperature - has been kept at a constant temp of 18 degrees celsius
too high alcohol - wines are only about 10% at this stage so not excessive
too much sugar - sg levels are 1.03 - 1.05 so no

Other causes I think I can discount are:
acidity - this is affecting all wines and I can't imagine all are too acidic
bacterical infection - no visible signs of infection but maybe there's something going on

So any suggestions about what I can do? My only thought is yeast nutrient which I did not add at the start.

Thanks in advance

You could try warming it up a little bit to see if that changes anything, maybe just a couple of degrees. I had a blacberry wine the was creeping along until I went from 64 F to 73 F then I saw it change within a few days.
What type of yeast were you using, and did you rehydrate it first? Could it have been old yeast?

I put in the airing cupboard but that did not make a noticeable difference. I used young's re-start yeast. I bought it a few days ago so it's not old and I rehydrated in half wine half warm boiled water.

As you said, I think nutrient would be the next logical step.

Cheers

HW

I'm not understanding your post. What was the OG of the wine?

wildfoodie said:

I put in the airing cupboard but that did not make a noticeable difference. I used young's re-start yeast. I bought it a few days ago so it's not old and I rehydrated in half wine half warm boiled water.

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Youngs states that it only works BELOW 8% ABV.

If you started at 1.100 and are now at 1.030, that's almost 10% ABV

You may not get much help if you don't post your recipe...... like.. What yeast did you use? What was your Starting gravity? Did you use any sort of yeast nutrients? How about pectic enzyme?

Anyway... Think about the timeline 6-9 months ago was..... October.... Not sure where you are from - but in most places, October is solidly into Fall - with temperatures running quite a bit cooler... If you kept it in a cool root cellar or a garage - no surprise fermentation would have stopped during the WINTER..... Even inside the house at Energy Saving temperatures around 65F - most wine yeast goes *Really* slow....

Suggestions... It's hard to give suggestions without knowing anything about it.... Like.. say the pectin floc'ed out of solution when the alcohol increased... It acts like a fining compound and will also take most of your yeast and nutrients with it.....
But.. Since it happened to *all* your wines.... maybe it's related to your yeast choice or OG or lack of nutrient or the temperature was lower than you think it should have been (Easy to do if it's sitting in a cupboard against and outside wall - it can be 10-degrees cooler in there)..... Not sure...

If you *Really* need to dry it out and can't just let it sit a while to see if it kicks back over in a month or 2 when it warms back up - try putting it somewhere it can warm up to around 22-25C and pitch a specially made starter using Champagne yeast. Also, don't forget the nutrients....

Thanks

You said acid was nt a problem, but you said you just did not think it would be. Blackberries have a lot of acid, test it, Pectic enzyme would have no effect on slow fermentation but Temp, acid and lack of nutrients would. If it is just creeping along and not stopped temp, acid and lack of nutrients are the only real causes

Thanks very much for your feedback guys. I added some yeast nutrient and that kicked things off. Hopefully the wines will all be fermented out to the desired SG levels within a couple of weeks