How often to wash the jar?


 Hi everyone,

I'm new to starters and sourdough. from the little I have read i understand that unwanted things can grow on the sides of the jar (the jar that I keep the starter in), and I wanted to know how often do I need to clean it. 



166 users have voted.


panfresca 2011 April 27

 Hi Tali

I've never had anything grow on the sides of the jar - the starter's biology actually fights against nasties. It is possible that unmixed flour could harbour mould or bacterial infection, but if my experience is anything to go on it's not a high risk.

I really only wash out the jar when it starts to look too messy - if I'm in a particularly neat mood that might be a couple of times a week, or sometimes up to a couple of weeks apart.


andrewd 2011 April 27

Like Kym said, it's only the unmixed flour that might harbour nasties. And obviously, some nasties might fall in if the lid's off.


But if you're regularly using your starter, it will constantly have a good population of yeast to keep nasties in check. Active yeast will be producing CO2 which will form a protective layer in the headspace of the jar. It's only after a couple of days without a feed that your yeast population will decline and the CO2 will disipate and therefore the nasties will move in.


So keep your friendly yeast well fed and bake on!



tali 2011 April 27

Thanks Kym and Andrew, but what if I only bake once a week? I usually bake once a week and for the rest of the week the starter is in the fridge...

I am afraid that this will enable nasties to develop on the sides of the jar and if I don't wash before feeding this will get mixed into the starter....

I really appreciate your opinion!




farinam's picture
farinam 2011 April 28

Hello Tali,

My starter has been in the same jar in the fridge for weeks and weeks.  I only bake once or maybe twice a week and nothing terrible has happened.

When I bake, I take mother from the jar to feed up for starter for the loaf and the replace that removed mass to 'feed' the mother.  I scrape down the sides with a spoon to get the most of anything sticking to the sides of the jar (including any unmixed flour) and give that a little mix in before putting back on the lid (loose fitting) and back into the fridge.



panfresca 2011 April 28

 Hi Tali

The chances of it happening are very tiny; starters are very robust things with lots of organisms which actively fight the nasties. In your situation, the chances are even less, because it will be stored at cold temperatures which the nasties don't like. 

You're unlikely ever to have a problem, but if it ever does happen all you do is make another starter - or you could just keep a spoonful or so in the freezer as insurance. I've heard of starters being frozen for a couple of years and still coming back to life when thawed.

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