Walk into any artisan bakery, and you'll notice the flour they use isn't just any old bag from the supermarket shelf. The truth is, flour is the foundation of your sourdough bread, and choosing the right one can be the difference between a loaf that's merely okay and one that makes you want to cancel your dinner plans just to eat another slice.
Let me share what I've learned over years of baking (and yes, a fair number of dense, disappointing loaves) about selecting flour that will help you create your best sourdough yet.
Why Flour Choice Matters So Much
Flour isn't just about providing structure—it's also feeding your sourdough culture and influencing flavor, texture, crust color, and how your dough behaves during fermentation. Different flours contain varying amounts of protein, minerals, enzymes, and natural sugars, all of which affect your final loaf.
The wild yeasts and bacteria in your starter absolutely love certain flours. Whole grain flours, for instance, contain more minerals and nutrients that feed fermentation, while highly refined white flours provide a cleaner canvas for milder flavors and lighter crumb structure.
Understanding Protein Content
Protein content is your first consideration. When flour meets water and gets worked, those proteins form gluten—the elastic network that traps fermentation gases and gives bread its structure.
For sourdough bread, you generally want flour with 11-13% protein content. This range provides enough strength to support a long fermentation and achieve good oven spring, but not so much that your dough becomes tough or difficult to work with.
Bread flour typically sits at 12-14% protein, while all-purpose flour ranges from 10-12%. Many experienced bakers use bread flour or a blend of bread flour and all-purpose to hit that sweet spot.
The Big Four: Essential Flour Types for Sourdough
Bread Flour
This is my go-to workhorse flour. Bread flour has higher protein content (usually 12-13%) and creates strong, elastic dough that can handle long fermentation times without collapsing. It produces loaves with excellent oven spring, an open crumb, and substantial chew.
If you're just starting out or want consistent, reliable results, bread flour is your best friend.
All-Purpose Flour
Don't underestimate all-purpose flour—it's more versatile than many bakers realize. With protein content around 10-12%, it creates a slightly softer, more tender crumb than bread flour alone.
I often use a 50/50 blend of bread flour and all-purpose when I want a less chewy texture or when making sandwich loaves. It's also more forgiving for beginners still developing their shaping skills.
Whole Wheat Flour
Whole wheat flour is where things get interesting. It contains the entire wheat kernel—bran, germ, and endosperm—which means more flavor, nutrients, and food for your fermentation.
The trade-off? Those bran particles cut through gluten strands like tiny knives, which can lead to denser loaves. I typically use whole wheat at 10-30% of my total flour weight. Even just 15% whole wheat adds beautiful nutty flavor and a gorgeous golden crumb without compromising structure too much.
Keep in mind that whole wheat absorbs more water than white flour, so you'll need to adjust your hydration accordingly.
Rye Flour
Rye flour is the secret weapon many bakers overlook. It contains pentosans—complex carbohydrates that absorb enormous amounts of water and create an incredibly moist, dense crumb with earthy, slightly sour flavors.
Rye also supercharges fermentation. Your starter will bubble enthusiastically with even a small amount of rye flour. I love using 10-20% rye in my sourdough for added complexity, though you can certainly go higher if you enjoy the distinctive flavor.
Be warned: rye has less gluten-forming protein than wheat, so doughs with high rye percentages become sticky and require different handling techniques.
Specialty and Heritage Flours Worth Exploring
Once you've mastered the basics, the world of specialty flours opens up fascinating possibilities.
Spelt flour is an ancient grain with a nutty, slightly sweet flavor. It has adequate protein but forms a more delicate gluten structure, so doughs need gentler handling and less fermentation time.
Einkorn flour, one of the oldest cultivated wheat varieties, produces tender crumb and unique flavor but requires careful gluten development.
Turkey Red, Red Fife, and other heritage wheat varieties have gained popularity among artisan bakers. These stone-ground, minimally processed flours offer remarkable flavor complexity you simply can't get from modern commodity wheat.
Fresh-Milled vs. Commercial Flour
If you're truly passionate about sourdough, you might consider milling your own flour. Fresh-milled flour contains all the wheat berry's oils and nutrients, which oxidize and diminish over time in pre-milled flour.
The flavor difference is stunning—fresh-milled whole wheat tastes vibrant and sweet rather than slightly bitter. However, fresh flour also ferments much faster and behaves differently in dough, so there's a learning curve.
For most home bakers, high-quality commercial flour from companies like King Arthur, Central Milling, or local mills that stone-grind in small batches will serve you beautifully.
What About Organic and Unbleached?
I always recommend unbleached flour for sourdough. Bleached flour has been chemically treated to whiten it and age it artificially. While this creates consistent baking properties for commercial applications, it can affect fermentation and produces less flavorful bread.
Organic flour isn't essential, but it tends to be less processed and may contain more mineral content that benefits fermentation. Many bakers report more active starters and better-tasting bread with organic flour, though quality non-organic flour from reputable mills can produce equally excellent results.
Reading the Bag: What to Look For
When shopping for flour, check the label for:
Protein content per serving - Calculate the percentage by dividing grams of protein by serving size (usually 30g) and multiplying by 100. Look for 11-13% for sourdough.
Ash content (if listed) - Higher ash content means more minerals and nutrients, which generally means more flavor and better fermentation.
Milling method - Stone-ground flours retain more nutrients and flavor than roller-milled varieties.
Origin and wheat variety - Single-origin or heritage variety flours often have more distinctive character than commodity wheat blends.
My Recommended Starting Formula
If you're wondering where to begin, here's the flour blend I recommend for beginners that balances flavor, structure, and forgiveness:
70% bread flour - Provides strength and reliable structure
20% whole wheat flour - Adds flavor and fermentation power without being overwhelming
10% rye flour - Boosts fermentation activity and adds complexity
This combination gives you an approachable dough that handles well, ferments predictably, and produces delicious bread with character. Once you're comfortable, start adjusting percentages to suit your taste.
Storage Matters Too
Even the best flour won't perform well if it's stored improperly. White flours stay fresh for 6-8 months in a cool, dry place in an airtight container.
Whole grain flours contain oils that go rancid, so store them in the refrigerator or freezer if you won't use them within a month or two. Let cold flour come to room temperature—around 21°C (70°F)—before mixing your dough for more predictable fermentation.
The Flour That Works for You Is the Best Flour
Here's the truth: bakers around the world create spectacular sourdough with vastly different flours based on what's locally available. A baker in rural France might use different flour than someone in California or Japan, and all can produce exceptional bread.
The "best" flour isn't necessarily the most expensive or exotic—it's the one that works with your technique, your environment, your starter, and your taste preferences.
Start with quality bread flour, experiment with small additions of whole grains, pay attention to how different flours behave in your hands and in your kitchen's specific conditions. Keep notes on what you try.
Over time, you'll develop an intuition for flour—how it feels, how it absorbs water, how it ferments—that no blog post can fully teach. That hands-on knowledge, combined with good flour, is what transforms you from someone following a recipe into a real bread baker.
Trust Your Hands (and Your Taste)
The most important tool for choosing flour isn't a protein percentage calculator or an expensive mill—it's your own developing sense of what makes bread you love to eat.
Buy a few different flours. Bake the same recipe with each one. Notice the differences in how the dough feels, how it ferments, and especially how the finished bread tastes. Your palate and your hands will tell you more than any expert (including me) ever could.
Because at the end of the day, the best flour for your sourdough bread is the one that helps you bake loaves you're proud to share—or too delicious to give away.
Happy baking!