Why Has My Wine Stopped Fermenting? Stuck Fermentation in Wine, Cider and Mead

Wine, cider and mead stall more often than beer. Malt wort is full of yeast nutrients, but fruit juice, sugar and honey contain very little. Here's how to tell if your brew is stuck and how to get it going again. For beer, see our separate guide to fixing a stuck beer fermentation.

Is it really stuck?

Don't go by the airlock. No bubbles can mean the fermentation has finished, or that the lid has a small leak. The only reliable test is a hydrometer reading taken in a trial jar:

• Finished: the reading is steady and close to the final gravity in your kit or recipe. Dry wines usually finish just below 1.000.
• Stuck: the reading hasn't changed over several days but is clearly above the expected finish.
• Just slow: the reading is still falling, even slowly. Leave it alone.

Hydrometers are calibrated at 20°C. A cold sample reads higher than it really is, so let the sample warm up or correct the reading before you decide.

Common causes

Cause	Why it happens	Fix
Too cold	Yeast slows right down in a cold room, garage or utility in winter	Move the brew somewhere warmer, or use a heat belt or heat pad
Not enough nutrient	Fruit, sugar and honey musts lack the nitrogen yeast needs	Yeast nutrient, 1 teaspoon per gallon
Campden added too soon	Sulphite inhibits yeast added within 24 hours	Wait it out, then re-pitch fresh yeast
Very high sugar	Strong musts stress the yeast and it gives up early	Re-pitch a robust yeast. Add sugar in stages next time
Tired yeast	Old or underpitched yeast runs out of steam	Rouse the yeast or pitch fresh yeast

How to restart a stuck fermentation

1. Confirm it's stuck with hydrometer readings taken a day or two apart.
2. Warm it up. Bring it gently into the yeast's comfortable range. For most wine yeasts that's room temperature, around 18 to 22°C. Avoid sudden jumps.
3. Rouse the yeast. Give the vessel a gentle swirl to lift the settled yeast back into suspension.
4. Add yeast nutrient, dissolved in a little warm water. Don't overdose: more nutrient won't speed things up.
5. Re-pitch if nothing changes after a couple of days. A robust wine yeast such as Lalvin EC-1118 is a common choice for restarts and copes with cooler rooms. It works best if you hydrate it first, then add it gradually with a little of the stuck wine.
6. Keep measuring. Fermentation usually picks up again within a day or two of a successful restart.

How to avoid a stuck ferment next time

• Use yeast nutrient in every fruit wine, cider and mead.
• Wait 24 hours after adding Campden tablets before you add the yeast.
• Keep the brew at a steady temperature. A heater or thermostat helps a lot in a UK winter.
• For very strong wines and meads, add the sugar or honey in stages. See our step feeding guide.

Frequently asked questions

How do I know if my wine fermentation is stuck?

Take hydrometer readings a day or two apart. If the reading isn't changing but is still well above the expected final gravity, it's stuck. If it's steady at or near the expected finish, it has finished.

Can yeast nutrient restart a stuck fermentation?

It often helps, especially in fruit wines, ciders and meads that are short of nutrients. Combine it with gentle warming and rousing the yeast, and re-pitch fresh yeast if needed.

What yeast should I use to restart a stuck wine?

A robust wine yeast such as Lalvin EC-1118 is a common choice. Hydrate it first and add it gradually to the stuck wine.

Does no bubbling in the airlock mean fermentation has stopped?

Not necessarily. It may have finished, or the lid may not be sealing fully. Only a hydrometer reading can tell you.

Can I bottle a stuck fermentation?

No. Leftover sugar can start fermenting again in the bottle and cause gushing or burst bottles. Restart it, or stabilise the wine properly once it's genuinely finished.