· Nora Whitfield
How to feed a sourdough starter: ratios, timing and reading the rise
Feeding is the whole of keeping a starter, and it is far simpler than the internet makes it look. What complicates it is that the right answer depends on your kitchen temperature, and almost nobody tells you that up front.
What a feeding ratio actually means
A ratio is written as three numbers — starter : flour : water — by weight, not by volume. So 1:1:1 with 50 g of starter means adding 50 g of flour and 50 g of water, giving 150 g in the jar.
The first number is what you keep. Everything above it gets discarded, which feels wasteful the first few times and is simply how it works: a starter that is never discarded becomes a huge quantity of increasingly sour paste that you cannot feed enough to keep healthy.
| Ratio | Meaning | Suits |
|---|---|---|
| 1:1:1 | Equal parts starter, flour, water | Counter storage, feeding once or twice daily |
| 1:2:2 | Double flour and water | A warm kitchen, or stretching to a longer gap |
| 1:5:5 | A small seed, a big feed | Warm weather, or feeding once before bed for the morning |
The pattern is straightforward: more flour and water relative to starter means a slower peak. If your starter is peaking and collapsing before you get back to it, feed it a bigger ratio rather than feeding it more often.
How often
Once a day works for most starters kept at ordinary room temperature. Twice a day suits a warm kitchen or a starter you are building up before a bake.
But "once a day" is a proxy for the real rule, which is: feed it when it peaks. A starter rises, reaches a maximum, then falls back as it exhausts its food. The peak is the moment it is strongest, and feeding on or near it keeps the culture vigorous.
Finding your own peak time takes about three days of paying attention. Mark the level at feeding time, then note when the rise stops climbing. That interval is your starter's rhythm, and it is remarkably consistent as long as the temperature is.
Why temperature changes everything
This is the variable that makes generic advice unreliable. Fermentation speed tracks temperature closely: the same starter, same flour, same ratio behaves like two different cultures in a 65 °F kitchen and a 78 °F one.
Practically, that means the schedule you read in a book written in a warm climate will not match your kitchen in February. A starter that peaks in five hours in summer might take twelve in winter, and feeding it on the summer schedule in winter means feeding it long before it is hungry.
Reading the temperature off the jar solves this in one glance. A stick-on strip covering 64 to 93 °F tells you which regime you are in, and therefore whether a slow rise is a cold starter or a problem.
Reading the rise properly
Here is the mistake almost everyone makes: judging the rise by how far it climbed up the jar rather than by ratio.
A starter going from 200 to 400 ml has doubled. One going from 400 to 500 has risen by a quarter — yet the second one covered more glass. If you are eyeballing height, you will read the second as the bigger event, and it is not.
A printed scale removes the ambiguity, which is why our jar is graduated from 100 to 900 ml. Slide a band to the surface at feeding time and the comparison is unavoidable: the number you started at, the number you reached.
When it peaks too early
You come back and the surface has fallen below the band. It did not fail — it rose, peaked and collapsed while you were out.
Three fixes, in order of how much they change: feed a bigger ratio (1:2:2 or 1:5:5), move the jar somewhere cooler, or use a stiffer feed with slightly less water. Any of them stretches the timing out to meet your schedule.
When it barely rises
First, check the temperature. Below about 68 °F a healthy starter looks inert, and the answer is patience or a warmer spot rather than intervention.
If it is warm and still sluggish, feed twice a day for three days with a 1:1:1 ratio and a little wholemeal flour in the mix. Wholemeal carries more of what the culture feeds on, and a short course of it usually restores vigour.
By weight or by volume?
By weight is more precise and it is what every ratio above assumes. A kitchen scale that reads in grams makes 1:1:1 trivial: 50 g starter, 50 g flour, 50 g water.
By volume works too, and plenty of people keep a starter perfectly well without ever weighing anything. The catch is that flour and water have very different densities — a cup of flour weighs far less than a cup of water — so "equal cups" is not the same as 1:1:1. If you feed by volume, use roughly two parts flour to one part water by cup measure to land near the same consistency, and judge by texture: a thick paste, not a batter.
Whichever you use, keep it consistent. A starter fed the same way every time settles into a predictable rhythm; one fed differently each day never does, and the peak time you worked out stops meaning anything. If you feed by volume, a set of measuring spoons kept beside the jar removes the temptation to eyeball it.
What consistency should it be?
A 100% hydration starter — equal weights of flour and water — sits somewhere between a thick batter and a paste. It should fall slowly off a spatula rather than pour.
Stiffer starters, made with less water, ferment more slowly and taste less sharp. That is a useful lever: if your starter peaks faster than your schedule allows, a stiffer feed buys you hours without changing anything else. Slacker starters do the opposite. Most people never need to touch this, but it is there if the timing fights you.
The discard question
Discarding feels wrong and is necessary. Without it the jar fills, the ratio of fresh food to old culture collapses, and the starter gets progressively more acidic and less lively.
Discard need not be waste — it goes into pancakes, crackers and flatbreads, none of which need the starter to be at peak. But do not skip the discard to avoid the waste; that is trading a small loss for a weaker culture.
Some numbers
starters sequenced across four continents in the largest survey of sourdough microbiomes to date. The variation between healthy starters is enormous, which is why your own peak time matters more than anyone else's schedule
— Landis et al., eLife, 2021
the span of a stick-on jar thermometer, which covers a cold winter counter through to a warm proofing spot
— Technical sheet, 2026
A minute a day
The whole routine, once it is habit: read the level, read the temperature, discard, add flour and water, scrape the walls, slide the band to the new surface, wipe and rewrite the date. Under a minute, twice a day at most.
What makes it stick is that none of it requires a notebook or a phone — the information lives on the jar. That is also why keeping the glass clear matters more than it sounds: a jar you cannot read through is a jar that has stopped doing its job.
If you are still building your starter, start with making one. If you bake occasionally rather than weekly, storing a starter covers the fridge routine, which changes the feeding schedule considerably. And if you are choosing a jar, what size you need and what makes one worth owning both help.