How to Feed Your Sourdough Starter

Feeding your sourdough starter means adding fresh flour and water to the existing culture so the wild yeast and bacteria have food to consume. Done consistently, feeding keeps your starter strong, active, and ready to leaven bread. Done poorly — wrong ratios, wrong timing, wrong temperature — it leads to a sluggish or unbalanced culture.

What Happens When You Feed Your Starter

When you add flour and water, the wild yeast and lactic acid bacteria in your starter begin consuming the sugars in the flour. Yeast produces carbon dioxide (which makes bread rise) and ethanol. Bacteria produce lactic and acetic acids (which give sourdough its flavour and preserve the bread).

The culture goes through four phases after each feed:

• Lag phase — the first 1–2 hours after feeding, minimal visible activity
• Rise phase — the culture accelerates, producing CO₂ and expanding in volume
• Peak — maximum volume, the ideal time to use the starter for baking
• Fall — the food is depleted, the starter collapses; acids accumulate

Your goal as a baker is to use the starter at or just before peak, and to feed it again before it collapses too far and the acid load builds up.

Feeding Ratios Explained

A feeding ratio describes the proportion of old starter to flour to water, always by weight. The format is starter : flour : water.

• 1:1:1 — equal parts. Feed 20g starter with 20g flour and 20g water. The culture peaks quickly (4–6 hours at 24°C) and is ideal for same-day baking.
• 1:2:2 — double the food. Peaks in 6–9 hours at 24°C. Good for baking the next morning.
• 1:5:5 — five times the food. Peaks in 10–14 hours at 24°C. Used when bakers want a slower, less acidic build, or to time overnight fermentation.
• Custom — anything goes. A 1:3:4 ratio produces a stiffer starter at 80% hydration; a 1:2:3 gives 150% hydration.

The higher the ratio (more food per unit of starter), the longer it takes to peak, and the milder the flavour. A lower ratio (less food) peaks faster but produces a more acidic culture.

Use the sourdough feeding calculator to get exact gram amounts for any ratio and hydration level.

How Much Starter to Keep

Most home bakers keep far more starter than they need. You only need a small seed to feed from — typically 10–30g. The rest is discard.

A practical approach: decide how much starter you need for your recipe (usually 100–200g), then back-calculate from your chosen ratio. For a 1:5:5 feed producing 200g total: keep 18g starter, add 91g flour and 91g water.

Keeping your maintained amount small has two benefits: you waste less flour, and you keep the acid load low (too much old starter starves the culture faster).

Discard: What It Is and What to Do With It

Every time you feed, you remove most of the old starter before adding fresh flour and water. The removed portion is called discard. It’s not waste — it’s unfed starter with a mildly sour flavour that works well in many recipes.

Discard can be used in:

• Pancakes and waffles (adds tang, helps with lift when combined with baking powder)
• Crackers (no leavening needed)
• Pizza dough (mix with a small amount of commercial yeast)
• Banana bread and muffins
• Flatbreads

Discard can be kept in a separate container in the fridge for up to a week. Use the sourdough discard calculator to see exactly how much flour and water is in your discard at any hydration level.

Counter vs Fridge: Which Schedule is Right for You

Counter feeding (room temperature)

Feed once or twice daily. The starter stays in continuous active fermentation and is always ready to use within a few hours of peaking. This is the best approach when you bake frequently (3–5 times per week).

Downsides: you use more flour over time, and you must feed consistently — missing a day means the starter gets very hungry and acidic.

Fridge storage (weekly maintenance)

Feed your starter, let it sit at room temperature for 1–2 hours to get activity going, then put it in the fridge. The cold slows fermentation to almost nothing. Feed once a week to keep it alive.

When you want to bake, take the starter out of the fridge 12–24 hours ahead of time, give it one or two feeds at room temperature, and use it when it peaks. This suits bakers who bake once a week or less.

The hybrid approach

Many bakers use a hybrid: keep the starter in the fridge most of the time, pull it out 1–2 days before a planned bake, feed twice daily at room temperature to build it up, bake, then return it to the fridge.

Flour Types for Feeding

White bread flour is the standard. It gives a consistent, predictable culture and a mild flavour.

Wholemeal / whole wheat flour ferments faster because it contains more native wild yeast and nutrients from the bran and germ. Adding 10–20% wholemeal to your feed can revive a sluggish starter or accelerate peak timing.

Rye flour is the most powerful accelerant. Even 5–10% rye dramatically speeds up fermentation and produces a more assertive, complex flavour. Many bakers add a small amount of rye to every feed to keep their culture lively.

All-purpose flour works but produces a slower, less active culture than bread flour. The higher protein content of bread flour feeds the culture better.

Avoid bleached flour — the bleaching agents can inhibit yeast activity.

Water for Feeding

Use room temperature water. If your tap water is heavily chlorinated, leave it in an open container for 30 minutes before using, or use filtered water. Chlorine can inhibit bacterial activity.

The temperature of your water matters in cold kitchens — using slightly warm water (26–28°C) helps get the culture active faster in winter.

Signs Your Feeding Routine is Working

• Starter reliably doubles within your expected window after each feed
• Consistent, predictable peak timing
• Clean, yeasty-tangy smell with no harsh vinegar notes
• Domed surface at peak, not flat
• Bubbles visible throughout the culture

If your starter is inconsistent — sometimes doubling in 4 hours, sometimes 12 — the most likely causes are temperature variation, inconsistent flour, or varying the amount of old starter you’re carrying over. Lock in all three variables and you’ll get reliable results.

Common Feeding Mistakes

Feeding too much at once. A 1:10:10 ratio is fine for a healthy starter, but for a sluggish one it’s too much food — the culture can’t work through it. Start with 1:1:1 and build up.

Feeding at the wrong time. The best time to feed is when the starter is past peak and starting to fall, not when it’s fully collapsed and starving. Feed on a schedule tied to when it naturally peaks.

Using cold water in winter. Cold water slows the culture from the moment of feeding. Use room-temperature water year-round.

Not discarding enough. If you keep 200g of old starter and add 200g flour and 200g water, the acid load from the old starter dominates. Keep your seed small relative to the new flour.

Changing flour brands mid-routine. Different flour brands have different protein levels and native yeast populations. Switching can throw off your timing for several days.

FAQs

How often should I feed my sourdough starter? If kept at room temperature, feed once or twice daily. If stored in the fridge, once a week is enough to keep it alive, though feeding before every bake produces a stronger result.

Can I feed my starter with self-raising flour? No. The added raising agents in self-raising flour will interfere with the culture. Use plain bread flour or all-purpose flour.

What if I forget to feed my starter for a week? If it was on the counter, it may smell very sour or have hooch on top. Pour off the hooch, discard down to 20g, and feed with fresh flour and water. Give it 2–3 regular feeds over 48 hours before trying to bake.

Does the water-to-flour ratio have to be equal? Not at all. Equal parts flour and water gives 100% hydration. You can run your starter stiffer (less water) or looser (more water) depending on preference. Most beginners start with 100% hydration because it’s easy to calculate and observe.

Can I use my starter straight from the fridge? You can, but it will be sluggish and underripe. Always bring it to room temperature and let it peak after at least one feed before using for bread. For discard recipes, straight-from-fridge is fine.

How do I know how much discard I have? If you keep 20g starter and feed 1:5:5 (adding 100g flour and 100g water), everything you removed before feeding is discard. Use the sourdough discard calculator to see the flour and water breakdown.