Ultimate Sourdough Starter Guide

One of the oldest forms of leavened bread has turned into the coolest carb to make and eat. Discover what makes sourdough bread unique, and the equipment you need to bake a beautiful loaf at home.

Recipe and tips for sourdough starter

Sourdough starter is a combination of flour and water, which, when mixed together, activates and produces carbon dioxide bubbles. This chemical reaction helps bread rise.

Unlike commercial yeast, a sourdough starter works with bacteria in the air. These wild bacteria produce acid, lending sourdough its distinctive sour tang.

The process of making sourdough starter from scratch takes about 5 days. Follow our instructions below for making your starter:

  • Day 1: Mix 50g strong white bread flour with 50g warm-to-touch water and leave, loosely covered at room temperature for 24 hours.
  • Day 2: Mix another 50g strong white bread flour with 50g warm-to-touch water into the existing mixture and leave, loosely covered at room temperature for 24 hours.
  • Day 3: Repeat the day 2 process again.
  • Day 4: Repeat the day 2 process again. 
  • Day 5: After four days, your sourdough starter should be looking nice and bubbly (if it doesn’t, keep feeding it with the above measurements once a day until it’s bubbly). Before you make your first loaf, discard all but 4 tbsp of the starter, feed it with another 50g of strong white bread flour and 50g warm-to-touch water, and leave, loosely covered for 8 hours. You are then ready to begin your first sourdough loaf.

Sourdough starter is best kept in a jar, with the lid a little open. This gives the starter room to breathe, meaning it won’t explode! You want to feed your starter with warm water and keep it in a toasty spot, as warmth helps wake up the starter and keep it nice and bubbly.

Sourdough Starter

Once you’ve created your starter, it’s possible to keep it alive for years, if not decades by following a few simple steps:

  1. When feeding your starter, discard all but 1 tbsp. This helps keep it fresh. You can keep the discard and use it to make crackers, pancakes and even crumpets.
  2. Once you’ve used your starter to make your levain (keep reading to learn more), you want to give your starter a really big feed (another 50g flour/50g water ratio) so it’s ready to use again next time you want to bake.
  3. When you’re not baking a loaf of sourdough, keep the covered starter in the fridge. When you want to bake again, take it out of the fridge 2 days before you want to bake, pour away any liquid that has pooled on top and feed it once or twice a day. The liquid might be grey, but this is completely normal.
  4. If you’re not going to be baking for a while (a few months), you can also freeze sourdough starter by spooning the liquid mixture into ice cube trays. When it’s time to bake again, let the cubes thaw, and feed twice a day for a few days. 

You’ll know when your sourdough starter is ready to use as it’ll have a sweet-sour banana-like scent and frothy head. If your starter doesn’t seem very active, it’s worth putting it somewhere warmer, or increasing the number of feeds up to two twice a day. And if it starts to smell of nail-polish remover, move it somewhere a little cooler. 

What is sourdough?

In its simplest form, sourdough is a leavened bread. This means there is a substance used to produce fermentation in the dough, which leads to the bread rising. 

With most breads, commercial yeast is the levain, whereas in sourdough, it is a starter made with naturally occurring yeasts.

To make sourdough bread, you need only a few key ingredients:

The process of making sourdough bread first involves making a starter which we’ve explained above.

It’s worth noting that there are numerous methods and recipes for making sourdough bread, and you’ll learn which way you prefer the more you bake. The recipe we’ve explained uses the folding method, and an overnight prove in the fridge.

Equipment you need for making sourdough

There are a few key pieces of equipment which will make your sourdough experience easier and more efficient.

  • Preserving jar: This clip-top jar is ideal for sourdough starter. You can keep the lid ajar letting the starter breathe, and also keep securely closed when storing in the fridge. A glass jar is great for letting you see how much the starter has grown each day.
  • Dough scraper: Use a dough scraper to keep work surfaces clean from any excess dough and to portion your dough into loaves.
  • Banneton: A banneton bread proving basket turns out beautiful loaves of sourdough bread, with distinctive concentric ridges. The second prove develops the texture and shape of your bread, which is why you can do it in a banneton for perfectly shaped loaves with crunchy crusts.
  • Lame or scoring blade: Before baking your sourdough, you need to score it. This helps the bread expand. You can hold the blade in two ways, curved or straight, great for if you want to create patterns on your bread.
  • Dutch oven: For baking sourdough, you want a pan with a lid. The lid keeps the steam in, letting the bread rise. Cast iron is a great material as it retains high heat, perfect for achieving a crunchy crust.

Sourdough Loaf Dutch Oven

What is a levain?

Sourdough bread is different from other breads in that it is made with a levain. The levain is just a larger version of your starter. 

  1. To make the levain, you take a portion of sourdough starter and mix it with equal parts flour and warm water. This is then left overnight, ready to make the dough in the morning.
  2. In the morning, the bubbly levain is mixed with flour and water and left to rest for 20 minutes. This step is called autolyse, and is when the gluten forms bonds and structure. After this step, salt is added.

Making sourdough might appear to be more time consuming than a farmhouse loaf, but a lot of time the dough sits and bubbles away on its own.

After the bread has had its first rest and the salt has been added, you want to gently fold the dough up and over, turning 90 degrees, creating pockets of air. This process (also known as bulk fermentation) is done every 30 minutes for around 4 hours.

Sourdough Process

How is sourdough bread different from other bread?

As well as being made with a levain, there are a few other key differences to sourdough bread:

  1. Sourdough bread is not made with commercial yeast, hence fewer ingredients, and some people find it easier to digest.
  2. The proving time for sourdough is a lot slower. The slow prove makes the final bread more flavourful, and also chewier.
  3. Sourdough bread keeps for longer before going stale.
  4. Studies of sourdough bakers’ hands show the microbes on their hands mirror that of the microbes in their starter, meaning the good bacteria is present when you eat and make the bread.

How long should I prove sourdough bread for?

Once you’ve got your dough ready, you can either bake straight away, or give the dough a second prove. This second prove is done in the fridge, overnight. A banneton helps the bread keep its shape, while the overnight prove lets the flavours slowly develop at a colder temperature. Even a few hours in the fridge is enough!

Sourdough Prove

How to bake sourdough bread

When you bake the sourdough, you want the oven to be at its highest temperature and steamy. The steam prevents a crust forming at the start of cooking - giving the loaf the best chance to rise. And the high heat results in a crunchy, crackling crust. 

If you don’t have a steam oven you can do in one of two ways:

  • Bake the sourdough in a pre-heated dutch oven with a lid. The lid keeps in water that evaporates from the bread, so the Dutch oven fills with steam, giving the loaf the best chance to rise. 
  • Place a roasting tin in the base of the oven, and 5 minutes before you put the bread in to the oven, pour a mug of boiling water into the roasting tin (taking care not to burn yourself as the steam evaporates)

Can sourdough be frozen?

It’s hard to resist sourdough when it’s fresh out of the oven, as it’s this point when the bread will have the crunchiest crust and chewy interior. If you won’t eat an entire loaf within a couple of days, it’s best to follow these instructions for freezing to prevent it from going stale.

  • Slice your sourdough.
  • Wrap each slice of bread in parchment paper, and place a few slices into a reusable freezer bag.
  • When you want to eat it, remove from the freezer and leave to defrost at room temperature.

Frozen sourdough bread is great for using for toast as well as making into breadcrumbs.

Is sourdough bread better for you than other types of bread?

When you’re making any kind of bread at home, it’s good because you know exactly what you’re putting into the dough, however sourdough has some slightly different properties.

Gut health is the biggest claim people link to sourdough. Some people can react poorly to commercial yeast, however as the fermentation process in sourdough is much slower, it makes the gluten easier to digest, and, those who struggle to digest gluten, may find sourdough easier on the gut.

Shop all bread making kit, and try our rye bread recipe.


  • When I first made my sourdough starter, I decided that I would not discard any as I thought it was a wasteful process for an occasional baker. I therefore, started and continued feeding with teaspoon measures of flour and water. This process took longer but became very vigorous; I increased the quantity of ingredients significantly the day before I wanted to bake. Thereafter, I decided that I wanted to keep my starter in a low maintenance way. A German lady, on her video, said that she kept a golf-ball sized starter for her next batch, in flour. In a container, she mixed flour into the starter until it was very, very dry. Then she placed a good quantity of flour on the top of the batch and stored it in the refrigerator. This would keep for about 6 weeks, she said. I have done the same and my new batch of starter ‘came alive’ again. I liked her ‘eye’ measurements because that is the way my mother taught me to cook and bake.

    Fabienne Mitchell on

  • Absolutely, that would be lovely. Rye flour and spelt flour are both great options.

    Ellie @ Sous Chef on

  • Hi,

    Can you use a mix of two flours? Such as bread flour and the flour? 25g each.

    Dionysios on

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