How to Make a Sourdough Starter from Scratch (Step-by-Step Guide)

If you’ve been curious about baking sourdough bread at home, it all begins with one magical thing: the sourdough starter. This bubbly, living culture is the heart of sourdough baking, replacing commercial yeast with natural fermentation.

With just flour, water, and a little patience, you can create your very own starter in less than a week. The best part? Once it’s alive and thriving, you’ll have a never-ending supply of baking magic to whip up breads, muffins, pancakes, crackers, and more.

In this guide, I’ll walk you through exactly how to make a sourdough starter from scratch, explain the signs of a healthy starter, and share tips for keeping yours happy and active.

🥖 What is a Sourdough Starter?

A sourdough starter is a mixture of flour and water that captures wild yeast and bacteria from the environment. These microorganisms ferment the mixture, producing gas (which causes bread to rise) and acids (which give sourdough its distinctive tang). Once established, the starter becomes your go-to leavening agent for all things sourdough.

Unlike store-bought yeast, a starter is alive and needs to be fed regularly. Think of it like a pet, but instead of walks and cuddles, you give it flour and water.

🛠 Equipment You’ll Need For Sourdough Starter

While you don’t need fancy gadgets, a few tools will make your life much easier:

• Digital Kitchen Scale – Accurate measurements are key.
• Thermometer Band or Temp Control Box – Helps maintain a cozy 70–75°F environment.
• Starter Jar – A medium mason jar works perfectly.
• Silicone Scraper – Gentle on your starter, won’t disrupt fermentation.
• Lid – For short or long-term storage.
• Breathable Cloth Cover – Allows airflow while keeping out contaminants.

(Starter kits sold on Amazon or Walmart usually include most of these items.)

Ingredients Needed

100 grams Whole Wheat Flour or Rye flour (gives depth of flavor) (could also use All-purpose flour)

100 grams of tap Water

⏳ How Long Does It Take?

Your starter will take about 5–7 days to be fully active. Some starters get bubbly in 3–4 days, while others need a little more time. Don’t rush the process, natural fermentation works on its own schedule.

🧑‍🍳 Step-by-Step Instructions

Day One

1. Measure 100 g flour (whole wheat or rye works best) and 100 g water.
2. Mix together in your starter jar until well combined.
3. Cover with a breathable cloth.
4. Store at room temperature (70–75°F).
5. Note the time — all future feedings happen at this same time daily.

Day Two

After 24 hours, you may notice tiny bubbles and a faint smell. Don’t panic, this is the first sign of fermentation!

• Stir gently.
• Replace the cover.
• Let it rest another 24 hours.

Day Three

Time to feed your starter!

• Discard half of your starter (about 100 g).
• Add 100 g of flour and 100 g of water.
• Mix well, cover, and rest 24 hours.

Days Four to Six

Repeat the Day Three feeding process:

• Discard 100 g.
• Add 100 g flour + 100 g water.
• Stir, cover, and let sit.

By this stage, your starter should show lots of bubbles and may start to double in size.

Day Seven

Your starter should now be:

• Doubling in size within 3–4 hours of feeding.
• Full of bubbles (big and small).
• Soft, spongy, and fluffy in texture.
• Pleasant-smelling (slightly yeasty and tangy, not sharp or pungent).

At this point, your sourdough starter is ready to use!

🔍 How to Know When It’s Ready

• It doubles in size.
• The texture is light, airy, and spongy.
• It smells pleasantly tangy (not sour in a bad way).

🚫 Signs Something’s Wrong

If your starter smells strongly acidic, like nail polish remover, or shows mold, it’s time to toss it and start over. Starters are hardy, but sometimes they just don’t cooperate. Don’t be discouraged, flour and water are inexpensive, and a fresh attempt often works beautifully.

📈 Growing a Bigger Sourdough Starter

Want a larger batch to bake more often? Easy!

• Use a larger jar.
• Feed every 12 hours instead of 24 hours until you reach the desired amount.
• Once established, you can return to once-a-day feeding.

🌾 Choosing the Right Flour

• Whole wheat or rye flour: Adds depth and stronger sourdough flavor (great for breads).
• All-purpose flour: Lighter, milder starter (perfect for pancakes, crackers, and muffins).

If you try a pre-made Amazon starter, note that they often use volume measurements (½ cup flour + ½ cup water) instead of weighing ingredients. Your results may taste a bit different depending on the flour base.

⭐ Recipe Tips & Tricks

• Use room temperature water (chlorine can inhibit fermentation, so filtered water is best if your tap water is heavily treated).
• Keep your starter at a steady temperature, avoid drafty or overly hot spots.
• Don’t skip feedings, consistency helps the yeast thrive.
• Mark your jar with a rubber band to watch your starter’s growth after feedings.

🙋 FAQs

Q: Can I use bleached flour?
A: Unbleached is best because it contains more natural yeast and bacteria.

Q: How often should I feed my starter once it’s ready?
A: Daily if left at room temperature. If stored in the fridge, feed once a week.

Q: Do I always have to discard half?
A: Yes, especially in the beginning. This helps maintain the acidity balance and prevents your starter from becoming too large to manage.

Q: How do I use the starter “discard”?
A: Don’t throw it out! Use discard in pancakes, muffins, crackers, or even pizza dough.

Your Starter Journey Awaits

Creating a sourdough starter may feel like a science experiment, but it’s also an incredibly rewarding kitchen project.

With just flour, water, and a little time, you’ll have a living culture that can transform simple ingredients into delicious, homemade sourdough bread and more.

Once you’ve made your starter, the sourdough possibilities are endless, and you’ll feel like a bread-baking pro every time those bubbly loaves come out of your oven.

For more homemade goodness, explore my collection of recipes and tips.

Sourdough Starter