Mead Fermentation Troubleshooting: Slow, Stuck or Smelly Mead

Mead fermentation problems are easier to solve when you measure before acting. An airlock can mislead you; a hydrometer, temperature reading and batch notes show whether yeast is consuming sugar.

Start with three checks:

1. Gravity: has it changed since the previous reading?
2. Temperature: is the mead within the yeast maker’s stated range?
3. Time: are you reacting to a few quiet hours, or to unchanged gravity over many days?

Keep everything that touches the mead clean and sanitised. Avoid repeatedly opening the fermenter “just to look”.

Quick diagnosis

No bubbles after pitching

A quiet airlock does not prove fermentation failed. Bucket lids and bungs often leak enough gas that the airlock never moves.

• Wait the yeast maker’s expected lag time, commonly a day or two.
• Check that the fermenter is not too cold or too hot.
• Look for foam, rising sediment or a changing aroma without opening unnecessarily.
• Compare a sanitised hydrometer reading with the original gravity.

If gravity is falling, fermentation is happening. Fixing a harmless lid leak is optional.

If gravity has not changed after an appropriate wait, review whether the yeast was added, whether it was expired or exposed to damaging heat, and whether the must was extremely concentrated. Follow the yeast producer’s rehydration and pitching advice. Do not keep adding random packets without understanding the cause.

Fermentation appears stuck

A stall means gravity stopped falling before reaching a plausible finish. Confirm it with at least two readings—not with bubbles.

Common contributors include:

• temperature outside the yeast’s range;
• too little yeast nutrient in honey’s nutrient-poor must;
• very high original gravity;
• low pH or other chemical stress;
• unhealthy or under-pitched yeast;
• the yeast reaching its practical alcohol tolerance.

Try the least invasive corrections first:

1. Move the fermenter gradually into the middle of the yeast’s temperature range.
2. Gently swirl to lift some yeast without splashing air into the mead.
3. Recheck gravity after several days.
4. Review the exact yeast, nutrient and recipe instructions.

Late nutrient additions, indiscriminate alkalinity adjustments and repitching require product-specific calculations. If the mead is strong, very sweet or smells seriously wrong, seek advice from an experienced mead maker with your OG, current SG, temperature, yeast, nutrient and timeline to hand.

Never bottle a suspected stall. Fermentation can restart in the bottle.

Sulphur or rotten-egg aromas

Hydrogen sulphide can appear when yeast is stressed, including by poor nutrition or unsuitable temperature. A slight fermentation-stage sulphur note may dissipate as carbon dioxide escapes and the mead matures.

Check:

• whether gravity is moving;
• whether temperature suits the selected yeast;
• whether the nutrient schedule matched the product directions.

Do not splash an almost finished mead in an attempt to remove odour; oxygen can create a different fault. Persistent strong sulphur after fermentation may need specialist treatment. Prevention through healthy fermentation is easier than correction.

Cloudy mead

Cloudiness is common in young mead and does not by itself indicate infection. Yeast, proteins, pollen and wax traces may take weeks or months to settle.

• Confirm gravity is stable.
• Give the mead more time at a steady, suitable temperature.
• Rack carefully off compact sediment if prolonged ageing is planned.
• Minimise oxygen and headspace after fermentation.

Fining agents and filtration are optional techniques, not substitutes for a completed fermentation. Follow their product directions if used.

Mead tastes too sweet

First measure gravity.

• Gravity is falling: fermentation continues; wait.
• Gravity is stable but unexpectedly high: diagnose a possible stall.
• Gravity is stable and plausible: the recipe may simply have finished sweet.

Balance can sometimes improve with maturation. Do not “fix” sweetness by adding acid or tannin blindly to the whole batch. Trial tiny measured additions in samples first, then scale carefully if you like the result.

Mead tastes harsh, hot or thin

Young mead commonly tastes more alcoholic or disjointed than mature mead. If gravity is stable and there are no spoilage signs, two to six months of cool, dark maturation may help.

Harshness can also come from hot fermentation, excessive spices, oxidation or poor yeast health. Keep notes so the next batch can be adjusted. Thinness may reflect a very dry finish; sweetness, acidity, tannin and alcohol all contribute to body and balance.

Infection warning signs

Not every floating speck is infection. Yeast rafts and bubbles are normal. Be more cautious with:

• fuzzy green, blue, black or white mould;
• putrid, faecal or intensely rotten odours;
• an expanding surface film accompanied by unpleasant flavour or aroma;
• ropey or slimy texture.

Do not taste visible mould or an obviously putrid batch. Discard it safely and replace scratched plastic or other equipment that cannot be cleaned thoroughly.

A thin film without mould can have several causes and requires experienced assessment. Isolate the batch and provide clear photographs, aroma, gravity, pH if available, and timeline when asking for help.

Oxidation

After early active fermentation, splashing and excessive headspace can lead to dull aroma, browning and stale, papery or sherry-like notes.

Prevent it by:

• siphoning rather than pouring;
• keeping the tube outlet below the receiving liquid;
• limiting unnecessary transfers;
• using a suitably sized ageing vessel;
• closing the vessel promptly.

Oxidation cannot reliably be reversed.

Dangerous bottle pressure

If ordinary bottles become over-carbonated, bulge, leak, push corks or break, treat them as a physical hazard.

• Keep people and pets away.
• Do not shake or casually handle warm bottles.
• Wear eye and hand protection if movement is unavoidable.
• Cooling can reduce pressure, but does not make damaged glass safe.
• Ask an experienced local brewer or homebrew shop how to manage the batch safely.

Prevention is the priority: use stable hydrometer readings and make still mead for your first batches.

Information to record when asking for help

Provide:

• batch volume and honey weight;
• original and current gravity, with dates;
• yeast name, amount and expiry date;
• nutrient product, total dose and timing;
• fermentation temperatures;
• pH readings if you have them;
• additions such as fruit, spices, acids or preservatives;
• photographs and a precise description of the aroma.

“Stopped bubbling” alone is not enough to diagnose a fermentation.

Related guides

• Make a beginner batch of traditional mead
• Mead hydrometer guide
• Mead-making equipment checklist

Further reading: BJCP Mead Faults and BJCP’s Mead Making Process.

Reviewed 11 October 2026.