Keeping a Sourdough Starter Alive and Fed
Sourdough starters are low-maintenance once you understand the rhythm. The culture wants to eat, reproduce, and be used. Your job is feeding it on schedule and not overthinking the variations in how fast it rises.
What you're actually managing
A sourdough starter is a self-sustaining colony of wild yeast (mainly Saccharomyces cerevisiae) and lactic acid bacteria (mainly Lactobacillus) living in a flour-and-water paste. It ferments, produces gas, and creates acid—all the things that make sourdough bread rise and taste the way it does. You feed it to keep the yeast and bacteria population strong and ready to leaven bread.
- a glass or ceramic jar (at least 1 quart / 1 liter capacity)
- a kitchen scale (grams preferred)
- a wooden spoon or silicone spatula
- a clean cloth or paper towel for covering the jar
What goes in.
- 100gall-purpose or bread flour (unbleached works best)
- 100gfiltered or tap water (room temperature)
Discarding and replenishing at peak
The starter rises predictably after feeding, then falls back down as the yeasts and bacteria consume the flour and produce organic acids. Feed when it has risen and shows bubbles on the surface—not when it collapses. This keeps the culture strong and prevents a buildup of dead yeast at the bottom.
The method.
Establish a feeding schedule based on temperature
At 70–75°F (21–24°C), feed once daily. At 65–70°F, feed every 12 hours or switch to once daily and keep the jar in a warmer spot (top of the fridge, near a window). Cold slows fermentation; warmth speeds it up. You'll quickly learn your kitchen's rhythm.
Check the starter before feeding
Look for bubbles throughout the paste and a slight dome or peak on the surface. You may see a thin liquid layer (hooch—mostly alcohol and acid) sitting on top; this is normal and means the yeast has been fermenting. Stir it back in or pour it off (your choice; both methods work).
Discard roughly half the starter
Scoop out and discard about half the jar's contents. You're doing this to reduce the amount of waste byproducts and keep the jar manageable. Don't be precise—50 grams out of 100g is fine; 60 is fine too. The goal is making room for fresh food.
Feed with equal parts flour and water by weight
To the remaining starter, add 100g water and 100g flour. If you prefer metric, use 50g starter, 50g water, 50g flour—the ratio is what matters, not the absolute volume. Stir until the flour is fully hydrated and there are no dry pockets. The mixture should look like a thick pancake batter.
Cover loosely and leave at room temperature
Drape a clean cloth or paper towel over the jar (don't seal it—the culture produces gas and needs to breathe). Leave it on the counter. In 4–8 hours at normal room temperature, you'll see new bubbles and a slight rise. This is the starter ready to use or ready to feed again.
Use or feed again on schedule
If you're baking, use the starter when it's at peak—bubbly and risen. If you're not baking that day, feed it again as you did in steps 3–4, then leave it out for a few hours before moving it to the fridge to slow fermentation overnight or longer.
Other turns to take.
Once-a-day feeding for less frequent bakers
Feed once daily at the same time each morning or evening. Between feedings, keep the starter on the counter at room temperature. This works well if your kitchen stays between 68–72°F. If it rises and falls before your next feeding, it's fine—just feed it anyway.
Refrigerated maintenance for occasional use
Feed the starter, let it rise for 1–2 hours on the counter, then cap it loosely and refrigerate. In the fridge at 40°F, fermentation nearly stops. Feed it once a week by removing it, discarding half, adding fresh flour and water, letting it come to room temperature, and then returning it to the fridge. This extends the time between feedings to a week or more.
Using a different flour type
Rye, spelt, or whole wheat flours ferment faster than all-purpose, so the starter rises more quickly and may need feeding more often. Whole grains also attract more wild microbes, which can create a more sour flavor over time. You can use these flours for feeding, but the timing will shift.
When it doesn't go to plan.
A starter doesn't need filtered water, but if your tap water is heavily chlorinated, use filtered or let tap water sit overnight to let chlorine evaporate.
Room temperature matters more than exact feeding times. A starter at 75°F fed at 8 AM might be ready again by 4 PM; the same starter at 65°F might not peak until the next morning. Let the rise guide you, not the clock.
Hooch (the clear liquid on top) is your starter telling you it's hungry. If you see a thick layer of it, the starter is overdue for feeding. Stir it back in before feeding, or pour it off—either way, feed promptly.
Never use a metal spoon with the starter if you can avoid it. Glass, ceramic, wood, or silicone won't react with the acids. Metal is usually fine for brief contact, but ceramic or wood is safer long-term.
If mold appears (fuzzy growth, any color other than white), discard the entire starter and start fresh. Mold is rare if the jar is clean and the culture is fed regularly, but it's a sign something went wrong.
A neglected starter (forgotten for weeks in the fridge) isn't dead. Feed it, wait for activity, feed again. Most starters revive within 2–3 feedings, even after a month of neglect.
The stronger the smell—tangy, yeasty, slightly vinegary—the more active and mature the culture. A weak smell or smell like acetone means it needs consistent feeding or a warmer home.
The ones that keep coming up.
How long does a sourdough starter take to get going from scratch?
A starter typically shows reliable bubbles and rise within 5–7 days of daily feeding with flour and water. It can take 2–3 weeks to become robust and truly predictable. Some starters peak earlier, some later—the microbes in your environment are different from someone else's.
Can I use whole wheat or rye flour instead of all-purpose?
Yes. Rye and whole wheat ferment faster because the bran particles and nutrient density feed the culture more readily. Your feeding schedule may shift—the starter might rise in 4 hours instead of 6. You can switch flours anytime; the culture adapts within a feeding or two.
My starter smells like nail polish remover. Is it dying?
That's acetone, a byproduct of fermentation when the culture is under stress—usually either too cold or underfed. Move the jar to a warmer spot and feed more frequently (every 8 hours instead of 12) for a day or two. The smell will fade once the yeast population rebounds.
How much of my starter should I use for a loaf of bread?
That depends on the recipe and how much fermentation time you want. Most sourdough recipes call for 50–100g of active (freshly fed and bubbly) starter per loaf. More starter = faster rise; less starter = slower, more sour bread. A standard loaf uses about 20–30% of the dry ingredients as starter by weight.
What if I want to bake less often but keep my starter?
Refrigerate it. Feed it once a week with the same discard-and-replenish method, let it peak for 1–2 hours at room temperature, then cap it and refrigerate. When you want to bake, remove it, feed it, let it come to room temperature and peak (4–8 hours), then use it. This stretches the feeding cycle to once a week.
Can I use tap water or does it have to be filtered?
Tap water is usually fine. If your water is heavily chlorinated, the chlorine can inhibit fermentation slightly. You can use filtered water, or let tap water sit uncovered overnight to let chlorine evaporate. Most home bakers use tap water without issue.
Is it normal for my starter to separate into layers?
Yes. Hooch (a thin liquid layer) forms as the yeast ferments and the paste settles. It's mostly water, alcohol, and acidity. Stir it back in or pour it off—both work. If you see a thick layer of gray or brown liquid, the starter is telling you it's overdue to be fed.
My starter has been in the fridge for two months. Is it still alive?
Almost certainly. Remove it, feed it, and wait. It may take 2–3 feedings before it shows bubbles and rises reliably again, but the cold just slows fermentation to a crawl. Keep it at room temperature between feedings until it's active again, then you can move it back to the fridge if you want.