Have you noticed your wash is taking longer to ferment in winter? Or maybe you’re not collecting as much spirit as you do in summer? You’re not alone.
As the seasons change, so should your approach to fermentation. Cold temperatures can significantly impact the performance of your yeast — and ultimately, the quality and quantity of spirit you produce.
Let’s explore why winter fermentation requires a few extra steps, and share five essential tips to help keep your yeast happy and your wash on track during the colder months.
The yeast in your sugar wash thrives within a specific temperature range. Too hot, and the yeast can die off. Too cold, and it goes dormant – pausing fermentation and potentially stalling your entire batch.
Each yeast strain has its preferred range:
Pure Distilling Premium Spirit Yeast works best between 20–26°C, with optimal performance at 24°C. Pair it with the Pure Distilling Reflux Condenser & Pure Distilling Output Cooler and it can produce up to 4.5-4.7L of high-strength spirit.
Our Specialised Rum Yeast, on the other hand, prefers a much warmer 35°C, which helps bring out those classic rum characteristics.
While fermentation may proceed faster at higher temperatures, this often stresses the yeast and can lower spirit quality. Colder fermentation might be cleaner, but it takes longer and doesn’t offer much improvement in final product.
With that in mind, here’s 5 tips on how to create the perfect environment for your wash during the winter months:
Every fermenter should have a stick-on thermometer. If you’ve purchased a Pure Distilling Distillery Kit, you likely already have one. If not, you can pick one up from your local home brew store for just a few dollars.
Stick it mid-way up your fermenter, and it will give you an accurate read on your wash’s temperature. Keep it between 20–26°C, and aim for 24°C whenever possible.
Tip: Always make sure the thermometer is visible – it’s the easiest way to keep tabs on your wash at a glance.
If your wash is running cold, a heater belt or pad is a great investment. It warms your fermenter from the sides, offering even heat distribution without disturbing the bottom layer of trub (sediment).
Covering the fermenter with a blanket is another technique that people use to keep the wash warm. If fermenting in a cold shed, using a large cardboard box to cover the fermenter & heater will insulate the air around the fermenter allowing less heat to escape. However, both these techniques will block our view of the stick-on thermometer, it is important that distillers are constantly checking temperature readings for any issues.
Warning: Always avoid using blankets and heaters together, the blanket traps the constant heating of the belt/pad and cooks the wash. For the same reason, avoid using an electric blanket.
It’s essential to stay aware of both room temperature and outdoor conditions throughout the entire fermentation period – especially during winter. Sudden drops in temperature can slow or stall fermentation if not managed properly.
In colder climates where overnight temperatures regularly fall below 0°C, many brewers find success by running two heater belts overnight to maintain that critical 20-26°C range. Then, as the day warms up, they’ll scale back to one heater belt to prevent overheating. This technique ensures your yeast stays active without being stressed by sudden shifts in temperature.
Remember: fermentation is a living process, and small changes in temperature can have a big impact on both time and spirit quality. Always base your heating adjustments on your thermometer readings – not how the air feels. Even if the room feels warm, your wash might still be too cold, especially if it’s sitting on a concrete floor or in a drafty area.
If you live in a particularly cold region, even heater belts might struggle to maintain a consistent fermentation temperature in the garage, shed, or laundry. In these cases, one of the simplest solutions is to bring your fermenter indoors – where the ambient temperature is more stable and easier to control.
Yes, it can smell – but there’s an easy fix:
Pure Distilling Smell Eliminator Kits attach to your airlock and neutralize odours completely. They’re around $30, and the cartridge lasts roughly five washes. This allows you to ferment in your lounge, kitchen, or even bedroom without complaint.
If your wash drops too low in temperature (typically below 16°C), fermentation can stall completely. Here’s how to bring it back:
Warm it up by following tips 1-4
Gently stir the wash to help reactivate the yeast.
If there’s still no activity after 12–24 hours, don’t add more spirit yeast – this increases the total nutrients in your wash which will form salts during distillation, in extreme cases this can turn your collected spirit blue!
Instead, add a pack of champagne yeast from your local brew store. It’s robust, reliable, and won’t affect the flavour or colour of your wash. Just note: it may take up to an extra 10 days to fully ferment.
With just a few small adjustments, you can keep your wash fermenting happily all winter long – and maintain both high quality and yield. Stick to the correct temperature targets, keep a close eye on your setup, and avoid overheating.
Have a winter fermentation trick of your own? Or questions about your wash setup? Drop a comment or Contact us – we’d love to hear from you.
— The Pure Distilling Team