To bake sourdough bread, you’ll need a starter. You can get one from a friend or relative, buy one online, or you can grow your own.

Growing your starter

A 100% hydration starter contains equal parts of water and flour. When you’re ready to bake with it, it’ll create a light loaf with a familiar, tangy sourdough flavor.

Materials

Flour – People have all kinds of opinions about what kind of flour is best for growing yeast. Some swear by rye flour while others will only make starters that are all-purpose flour; I use whatever I’ve got lying around and this very laissez faire method hasn’t failed me yet.

Water – Because yeast acts sluggish in cold water (below 65ºF) and will die in temperatures warmer than 95ºF, room temperature water is the way to go. Some bakers use distilled water or let their water stand overnight to let chlorine dissipate, but I think water fresh from the tap works just fine. If it’s good enough to drink – and NYC has the champagne of water, after all – it’s good enough to bake with.

Large glass jar with a lid – Give yourself fewer dishes to wash: grow your starter in the same jar where you’ll store it long-term. Glass is imperative because the acid produced by lacto-bacteria will react with some types of metals. A 1 quart wide-mouth mason jar will do the trick, but 1 liter weck jars are really pretty and even easier to fit a spatula into.

Spatula – A rubber spatula lets you mix in the flour and water, aerate your starter, and clean off the insides of the jar each day. One that’s made out of a single piece of rubber is easiest to clean.

Kitchen scale – While most Americans are used to baking with cups and teaspoons, baking bread really requires a scale. You can pick up a totally acceptable digital scale for as cheap as $10. If you want to get fancy, solar-powered scales run $40 and up and smart scales that link to your phone or ipad sell for $80.

Rubber band – If you want to be able to really watch your starter’s progress, find a rubber band that fits around your jar so that you can mark your culture’s starting point.

Observation record – Print out this observation record (or make your own) so that you can track what your sourdough looks, feels, smells, and tastes like each day that it’s growing. This will help you understand what’s going on and keep you on track for the first five days.

Timer app – For me, the most frustrating part of growing a sourdough starter is getting the timing right. Officially, you should be paying close attention and becoming one with your starter so that you can sense its every desire. Unofficially, you have to work and sleep and eat and have a life that prevent you from babysitting a bowl of bacteria and yeast for a week. Maintain your sanity by downloading Timeglass, a timer app that lets you set multiple steps and save timers to use over and over. You can create 3 timers for free or buy unlimited timers for $2.99.

Anything else? – Nope. Nada. Sometimes you’ll hear that tossing a grape or other fruit in your starter will help spur growth. Don’t do it! There’s plenty of wild yeast in the air and on your flour and sugar in fruit inhibits yeast growth. In all likelihood, adding fruit to your starter will add nothing but mold.

Instructions

Day One

1. Measure jar – When you start discarding portions of your starter, you’ll want to know how much your jar weighs. Weigh the jar and write the mass on the jar so that you don’t forget.
2. Measure flour – Growing a sourdough starter requires regular feeding. This can be tough for anyone with a hectic schedule, so you can make it easier on yourself by pre-measuring. Measure 60 grams of flour in the jar for today’s use and then 60 grams of flour each in four small bowls for the rest of the days.
3. Mix – Combine and stir today’s 60 grams of flour and 60 grams of water in your jar and stir with a spatula until all the water is incorporated.
4. Store in a warm, but not sunny place – Yeast is most active when the temperature is in the high 70ºF, low 80ºF range. Store your jar away from drafts, which will slow yeast down, and sun, which contains Uv light that kills yeast
5. Set 24 hour alarm – You’ll feed your starter exaaaaactly (or as close as possible to exactly) a day from now. Set a timer, alarm, or calendar reminder so that your starter has the best chance of survival.
6. Make your initial observations – Right now, your mixture should be pretty viscous. It will stick to the spatula and temporarily hold its shape. The only thing you’ll smell is flour because no big lacto-fermentation action has happened yet.

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Day Two

1. Observe and adjust marker – Today, you’ll notice that your starter looks a tiny bit bubbly and is starting to smell… off. Call it vinegary, bitter, like gym socks – there’s no getting around the fact that the starter stinks. This happens because the lacto-bacteria hasn’t quite gotten around to killing off all the bad bacteria and is totally normal at this stage in the process. Your starter might have formed a hard crust overnight. Go ahead and break it up with your spatula and stir it in. While there’s not going to be much rise on day two, marking the starting height by adding a rubber band will let you know when the yeast does start rising.
2. Feed – Add 60 grams of flour and 60 grams of water, stir, and clean the sides of the glass with your spatula.
3. Set 24 hour alarm

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Day Three

1. Observe and adjust marker – Today, you’ll notice that your starter looks a bit more liquid than yesterday. There may be a few bubbles or even some liquid on the surface. This is all happening because yeast and lacto-bacteria are starting to take over the mixture and produce alcohol, carbon dioxide, and lactic acid. Move your rubber band to the top of the mixture to mark the starting point.
2. Feed – Add 60 grams of flour and 60 grams of water, stir, and clean the sides of the glass with your spatula.
3. Set 24 hour alarm

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Day Four

1. Observe and Adjust marker – Today, you’ll notice more bubbles on the surface and a more pleasant sour smell as the lacto-bacteria continues killing off the bad bacteria. Depending on how warm the starter is, it might rise overnight, leaving streaks on your jar. Your starter is almost ready to use.
2. Discard – Discard a portion of your starter so that 200 g remains. Weigh the jar and starter, then subtract the mass of the jar. For example, if my jar and starter together weigh 760 grams and my jar weighs 400 grams, I know I have 360 grams of starter. I’ll remove 160 grams of starter so that total mass of the jar and starter (what till show up on the scale) is 600 and the total mass of the starter is 200.
   • Discarding is essential for a healthy, flavorful starter. Lacto-bacteria grows much faster than yeast and inhibits yeast activity. Discarding part of the starter keeps lacto-bacteria and lactic acid levels low so that yeast can thrive. While discarding may seem wasteful, this portion has already done its job: it’s fed the yeast and lacto-bacteria.
   • There’s plenty you can do with your discard other than throwing it away, though. After a few weeks, your starter should be nice and mature; you can give the discard from your feedings away to friends so they can bake their own sourdough. If you don’t have any crafty friends, you can use the discard to make any other baked goods. Because it’s half water, half flour, you can substitute it in almost any recipe that calls for both. If that’s too much math, there are thousands of sourdough discard recipes out there.
3. Feed – Add 60 grams of flour and 60 grams of water, stir, and clean the sides of the glass with your spatula.
4. Set 24 hour alarm

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Day Five

1. Observe and Adjust marker – Today, your starter should smell more familiarly like sourdough. It should be nice and bubbly and will rise and fall as the yeast respirates.
2. Discard – From now on, you’ll always discard a portion of the starter to keep it fresh and maintain a constant amount of starter. Discard enough starter so that you’re left with 200 grams.
3. Feed – Add 60 grams of flour and 60 grams of water, stir, and clean the sides of the glass with your spatula.
4. Set alarm – At this point, your starter is ready to use. Wait until it’s doubled in size (approximately 12 hours) and then use it for baking or store it in the fridge.

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Maintaining Your Starter

Your starter can last indefinitely as long as you feed it when it wants to be fed. Underfed starter will die because there’s not enough flour for all your little yeasties and lacto-bacteria to eat. Overfeeding will dilute the culture and eventually kill it.

At room temperature, a starter needs to be fed at least once a day. If you want a really vigorous starter, twice a day. Put your starter in the fridge, though, and all the microflora will hibernate. At fridge temperature, your starter only needs to be fed once a week.

Here’s your weekly feeding plan for weeks when you’re not baking:

1. Remove hooch – When you remove your starter from the fridge, it will likely have a few millimeters of clear liquid on top. This “hooch” is just yeast-produced alcohol that has condensed. While you can stir it in, it will make your bread more bitter. Instead, carefully pour it off.
2. Discard – Discard a portion of your starter so that you’re left with 200 grams. Don’t forget to share your discard or use it for something else! Depending on how much you used last time you baked, you may not need to discard any.
3. Feed – Feed your starter 60 grams of flour and 60 grams of water, just like when you first grew your starter. Stir and scrape down the sides.
4. Allow to rise – Allow the just-fed starter to rise until it has doubled in size (approximately 12 hours). Once it’s ripe, you can store it.
5. Store – Seal your jar tightly and place it back in your fridge until next week.
6. Set alarm – Set a weekly calendar reminder so that you never forget to feed your starter.

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Prepare Starter for Baking

While this weekly maintenance will keep you going indefinitely, there’s going to come a week when you want to bake with your starter. The protocol it mostly the same, but requires a little more planning and repetition.

Here’s your feeding plan for weeks when you want to bake with your starter:

1. Plan 1-2 days in advance – You want a nice, vigorous starter if you’re going to bake with it. This means at least two feedings. When I’m going to bake, I like to time my feedings 12 hours apart (which is just a few hours after the starter has doubled in size and started to drop). I usually start a loaf Saturday morning so I pull out my starter Friday morning. After giving it its first feed, I feed it again Friday night so that it’s nice and bubbly Saturday morning.
2. Remove hooch – Pour that slime off.
3. Discard – Discard a portion of your starter so that you’re left with 200 grams. Depending on how much you used last time you baked, you may not need to discard any.
4. Feed – Feed your starter 60 grams of flour and 60 grams of water. We use a little less since we’re going to feed it a few times. Stir and scrape down the sides.
5. Allow to rise – Allow the just-fed starter to rise until it has doubled and started to drop. This should take around 12 hours but might be quicker in warmer kitchens. If your starter is still growing, wait another hour or two for it to start to drop to avoid overfeeding.
6. Set alarm – Set an alarm for 12 hours so that you don’t forget to feed your starter
7. Repeat – Repeat the discard, feed, set alarm, allow to rise steps as many times as you want until you’re ready to bake. One more time is sufficient.
8. Use – Use your starter to make dough when it has doubled in size. At this point, it’s at peak yeast activity and should be able to pass the float test, something we’ll talk about this more in another post.
9. Store – There’s no need to feed your starter after you use it. Seal it up and put in back in the fridge immediately.