You don’t need to buy a
sourdough starter.

Yes — several bakeries and marketplace sellers ship dehydrated or live starters, usually for £10–25 including postage. But a bought starter still arrives dormant and needs several days of feeding to reactivate before it’s usable, which is roughly the same wait as growing one from flour and water at home.

Around 5–7 days for a reliably active starter, sometimes up to 14 in a cool kitchen. You’ll usually see bubbles within 24–48 hours, but that’s early activity, not readiness — the full guide covers what to expect day by day.

The most common causes are a kitchen that’s too cold, heavily chlorinated tap water, or flour that’s low in the wild yeast and bacteria needed to get things going, and wholemeal or rye flour usually kickstarts a sluggish starter faster than white. If yours is showing other symptoms too, the starter troubleshooting guide covers hooch, acetone smells, and dense bread as well.

No meaningful difference once it’s established. After a few weeks of regular feeding, a starter’s flavour and strength come from your local flour, water and kitchen temperature, not from where the culture originally came from.

Wholemeal or rye flour to get it going — both carry more of the wild yeast, bacteria and nutrients a new starter needs in its first few days. Once it’s active, many bakers switch to white bread flour for a milder, more predictable starter.

Well under £1 in flour and water over the course of a week, compared with £10–25 for a shipped starter once postage is added.

Rarely. A layer of dark liquid on top ("hooch") or no visible activity after weeks in the fridge usually means dormant, not dead, and a few feeds will often bring it back. Genuine spoilage shows up as pink or orange streaks, or a foul smell — at that point, start again, which costs almost nothing either way.