Sourdough Pain de Campagne with a Poolish: The Autumn Bake-Along Where the Calculator Did the Heavy Lifting

How the Calculator Changed the Plan

My original instinct was to use 40% poolish. I have seen that figure in a few French bread books and it felt right. But when I plugged my numbers into the Preferment Calculator, something shifted. The calculator showed me clearly that at 40% poolish with a 74% final hydration target, I would need to add barely any water in the main mix because the poolish itself is already 100% hydration. The numbers got tight and awkward, and the margin for error shrank fast.

At 30% poolish, everything balanced neatly. The preferment contributed 135g flour and 135g water, leaving me with clean, easy numbers for the final dough: 405g total flour, 270g total water (minus the 135g already in the poolish, so 135g to add in the main mix plus an extra 65g for the warm final water). That clarity is the whole point of running the calculation before you start weighing anything out.

Night Before: Making the Poolish

I did this on a Friday evening with some Shed Seven on in the background (yes, I know, not house music, it was a different mood). Weigh 135g of strong white flour into a clean bowl. Add 135g of cool water and stir until there is no dry flour left. It will look like thin wallpaper paste. Add 1g of instant yeast and 15g of your active starter, stir again, cover with a shower cap or clingfilm, and leave at room temperature overnight.

In the morning, the poolish should have domed slightly, be covered in bubbles, and smell faintly of beer and yoghurt. If it has already collapsed back to flat, it went too fast and your kitchen is too warm. Next time, use colder water or put it somewhere cooler.

Morning: Building the Final Dough

Combine 315g of white flour and 90g of wholemeal flour in a large bowl. Add the poolish and 200g of warm water (around 28°C). Mix until everything comes together into a shaggy mass, then cover and leave for 30 minutes. This rest is not an autolyse in the strict sense because the poolish is already active, but it gives the flour time to absorb the water before you add the salt.

After the rest, sprinkle over the 10g of salt and squeeze it through the dough with your fingers until fully incorporated. It will feel slippery for a moment and then pull back together.

The Bulk: Folds, Patience, and a Good Podcast

At an average October kitchen temperature of around 20 to 22°C, this dough needs roughly four hours of bulk fermentation. Perform four sets of coil folds, one every 30 to 45 minutes for the first two hours, then leave it alone. By the end, the dough should feel noticeably airier, pull away from the sides of the bowl cleanly, and jiggle with a slight wobble when you shake the container.

Because the poolish has already been fermenting overnight, the bulk moves at a good pace. This is one of the things the Preferment Calculator helps you account for: a higher poolish percentage would push bulk fermentation faster, which is useful in some contexts but on a cold autumn morning when you want to get out for a walk first, 30% gives you time to breathe.

Shaping and the Overnight Proof

Turn the dough onto an unfloured surface (the slight tackiness helps you build tension). Pre-shape into a rough round, leave for 20 minutes uncovered, then do a final tight round shape. Drop it seam-side up into a well-floured banneton, or a bowl lined with a floured cloth. Cover and refrigerate overnight, or for at least 10 hours and up to 16.

I did mine for 13 hours and baked straight from the fridge the next morning. Cold dough holds its shape better when you score it and the contrast between the cold interior and the hot oven gives you a better crust.

Baking: Dutch Oven, Screaming Hot

Preheat your oven to 250°C (fan 230°C) with a Dutch oven inside. You want at least 45 minutes of preheat time because you need the cast iron genuinely saturated with heat, not just the oven air temperature. Turn the dough out onto a square of baking paper, score it with a single curved cut or a cross, and lower it into the Dutch oven using the paper as a sling.

Lid on for 20 minutes. Lid off, temperature down to 220°C (fan 200°C) for a further 22 to 25 minutes until the crust is a deep, genuine brown. Not pale gold, not caramel: proper chestnut. Pull it out and leave it on a wire rack for at least an hour before you cut in. The crumb is still setting inside and if you slice too early, it will be gummy in the middle.

What Came Out of the Oven

This loaf was, honestly, one of my better ones this year. The crust had that proper shattering quality when you tapped it. The crumb was open and slightly irregular, with a creamy colour from the wholemeal, and the flavour was exactly what I was after: mildly tangy, wheaty, with that unmistakeable poolish depth underneath. It is the kind of bread that is genuinely excellent with good cheese, which is convenient because I had a wedge of Comté sitting in the fridge specifically for this purpose.

The key was the preferment calculation. Getting the percentages right meant the timing worked, the hydration balanced, and I was not making adjustments by feel in a panic at 7am. The maths is not glamorous but it is what separates a bake you can repeat from one you sort of got away with.

If you bake this one regularly, it is worth saving the formula somewhere. I have been using DoughRise Pro to keep all my working formulas and notes in one place, which means when I come back to this loaf in December with a slightly colder kitchen, I have the previous bake data to work from rather than starting from memory.