How to revive a neglected sourdough starter

Step by step

A clean jar matters: the old one holds dried, acidic starter. See which jar to use.

1. Pour off any grey liquid and scrape away dried or discoloured starter from the top and sides.
2. Take 50 g from the middle into a clean jar.
3. Feed it 50 g unbleached all-purpose flour and 50 g warm, not hot, water, as King Arthur does.
4. Keep it warm and feed again every 12 hours.
5. When it doubles within 4 to 8 hours of a feed, it is back.

How long it takes

The longer it sat unfed, the longer it takes, King Arthur says. As a rough guide of ours: after a missed day or two, one or two feeds; after a few weeks in the fridge, 2 to 4 days; after months, up to a week. If it is still sluggish after a week of warm, regular feeds, check why a starter stays weak.

Alive, or not?

Any rise or bubbles after the first two warm feeds means it is alive; keep feeding. If nothing happens, keep going: the longer it sat unfed, the longer it takes to wake, and King Arthur's advice is simply to repeat the feeds. Our rough limit is a week of warm, regular feeds after months of neglect. King Arthur gives a shorter one for a starter that has dried to a hard block: if three or four days of daily feeds bring no growth and no bubbles, you might as well start over, stirring some of the old starter into the new. Starting over is a practical choice, not proof the old one has died; a spoonful from a friend's starter is the fastest way back.