Cold Weather Sourdough Starter Maintenance: How to Keep Your Starter Active Through Winter  

Winter on the Mornington Peninsula might be mild compared to Melbourne's CBD chill, but even a modest drop in temperature can bring your sourdough starter to a near standstill. If your starter has been sluggish, slow to rise, or smelling a little off lately, the cold is almost certainly the culprit — and the good news is, it's one of the easiest problems to fix once you understand what's happening.

Whether you're working with our gluten-free starter kit or our organic wheat starter, the principles are the same: your starter is driven by living microorganisms, and those organisms are sensitive to temperature. Here's everything you need to know to keep your starter thriving through the cooler months.

Why Cold Weather Affects Your Starter

Sourdough starters are home to two types of microorganisms: wild yeasts and lactic acid bacteria (LAB). Both are temperature-sensitive.

At their ideal working temperature — roughly 24–28°C — these organisms are active, hungry, and productive. They consume the sugars in your flour, produce carbon dioxide (which makes your dough rise), and generate the organic acids that give sourdough its characteristic tang.

Drop the temperature to 15–18°C, which is common in unheated Australian homes during winter, and the activity slows significantly. Your starter will still be alive — it's not dead — but it may take two or three times longer to peak, and it may produce a different flavour profile, often more sour and acidic.

Drop it further, below 10°C (say, if you leave it near a drafty window or in a cold pantry), and fermentation can almost completely stop.

This explains why your starter that bubbled away reliably all summer is now sitting there looking flat and defeated. Nothing is wrong with it — it just needs warmth.

Signs Your Starter Is Cold-Stressed

Before adjusting your routine, it helps to confirm that temperature is actually your issue. Cold-stressed starters typically show one or more of these signs:

• Slow or no rise after feeding. A starter that used to double in 4–6 hours is now taking 10–14 hours — or not visibly rising at all.
• Liquid (hooch) forming on top. This grey or dark liquid is alcohol produced by hungry yeast. It means your starter has exhausted its food supply and has been waiting too long between feedings.
• Very sour or vinegary smell. At cooler temperatures, acetic acid bacteria (which produce vinegar-like acidity) become more dominant relative to lactic acid bacteria (which produce a milder, yoghurt-like sourness). This isn't harmful, but it does shift the flavour.
• Dense, heavy texture. A well-fed, active starter should be airy and light when you stir it. Cold starters feel thick and almost gluey.
• Starter sinking quickly after peaking. In cold conditions, starters can peak earlier and more subtly, then fall before you notice they've risen.

Finding a Warm Spot in Your Kitchen

The most effective fix is simply finding the warmest spot in your home for your starter to live during the cooler months. Here are some options, in rough order of reliability:

On top of the fridge.

The motor at the back generates gentle, consistent warmth — often 2–4°C above ambient. It's one of the classic sourdough baker's tricks, and it works.

Inside the oven with just the oven light on.

If your oven has an incandescent globe (not LED), turning on just the oven light can hold the interior at around 24–28°C — almost ideal for fermentation. Check the temperature with a thermometer before committing.

A Proofing Box or a Starter Warming Pad?

If you bake regularly through winter and want a simple, economical solution for both your starter and dough, our Electric Fermentation Heat Box takes the guesswork out of fermentation. It maintains a consistent temperature, is pre-set to the ideal 24–28°C range, is USB-powered, and folds flat for easy storage when not in use.

If you're looking for a sleek, compact solution specifically for your starter, while still allowing your dough to bulk ferment naturally at room temperature, our Starter Warming Pad is a great choice. It provides gentle, controlled warmth to keep your starter active and healthy throughout the cooler months. It comes with an Australian wall plug, precise temperature control (21–38°C) and an auto shut-off function for convenience.

Whichever option you choose, maintaining a consistent temperature can make a huge difference to starter activity, fermentation times and overall baking results.

→ Shop the Electric Winter Fermentation Solutions here

Adjusting Your Feeding Schedule for Winter

Temperature affects not just how fast your starter rises, but how quickly it depletes its food supply. In winter, you generally need to feed less frequently — not more.

This is counterintuitive for new bakers who assume a slow starter needs more feeding. But overfeeding a cold starter dilutes the microbial population and makes recovery harder. If your starter is at 15°C and you're feeding it every 12 hours as you did in summer, you're likely feeding before it has fully peaked — which means you're discarding a starter that still has work to do.

A practical winter feeding approach:

Watch your starter, not the clock. Feed it when it has risen and is just starting to fall — this is the "peak" and the ideal moment to feed. In winter, this might be every 18–24 hours at room temperature.

If you're baking every few days (or less), keep your starter in the fridge between bakes and feed it once a week. Pull it out 12–24 hours before you need it, feed it, find a warm spot, and let it peak before using it in your bake.

Using Warmer Water to Give Your Starter a Boost

One simple technique for giving a sluggish winter starter a quick boost: use slightly warmer water when you feed it.

Rather than using cold tap water (which in winter can easily be 12–14°C and will cool your starter down further), use water that's been warmed to around 30–35°C — comfortably warm, but not hot. Hot water above 40°C will harm your cultures, so err on the side of caution.

This warmer water will bring your starter's overall temperature up slightly and give the yeast a more hospitable environment to activate. Combined with a warm spot in the kitchen, this alone can noticeably improve activity.

A Note for Gluten-Free Starter Bakers

If you're maintaining one of our gluten-free starters, the principles are identical — your starter is just as temperature-sensitive as a wheat one. However, there are a couple of extra things to watch:

Gluten-free starters can appear less active even at their best, because the flours they're based on (rice flour, sorghum, and others) don't trap gas the same way wheat does. Don't be alarmed if your gluten-free starter bubbles rather than dramatically domes — bubbling is activity, and activity is what you want.

In cold weather, gluten-free starters can also take on a more pronounced sour note. This is normal. If the flavour becomes uncomfortably sharp in your finished bread, try shortening the fermentation time slightly, or reducing the proportion of starter in your recipe.

What About Storing Your Starter in the Fridge Over Winter?

If you're not baking regularly — say, once a week or less — refrigerating your starter is the most practical approach. The fridge (around 3–5°C) effectively pauses fermentation without harming your cultures. They go dormant rather than die.

To maintain a fridge-stored starter through winter:

1. Feed it as usual (1:1:1 ratio of starter to flour to water, or your preferred ratio). This may mean you'll need to discard.
2. Leave it at room temperature for 1–2 hours to let fermentation begin.
3. Place it in the fridge.
4. Repeat once a week, minimum.

When you're ready to bake, pull the starter out the evening before, feed it, and leave it in a warm spot overnight. By morning it should be active and ready. If it's been neglected for a few weeks, give it two consecutive feeds (morning and evening) before relying on it for a bake.

The "Float Test" in Cold Weather

You may have heard of the float test — dropping a small amount of starter into water to see if it floats, which indicates it's active enough for baking. It's a useful rough guide, but be aware that it can be misleading in cold conditions.

A cold starter may float (because it has some gas trapped) but still be past its peak and on the decline. It may also fail to float but still be capable of leavening bread — especially if your recipe uses a long, slow overnight fermentation. Use the float test as one data point, not the final word.

A better winter test: look for a dome at the top of the starter, visible bubbles throughout (not just on the surface), and a pleasant, slightly sour smell. If you have all three, you're good to bake.

Quick Reference: Winter Starter Troubleshooting