Beginner's Starter moldy after 1 day 18hours

Hi, Sarah. I have a problem here I'm a beginner, just started to make my own starter. But after 1 day 18 hours later my starter grow fungus and moldy on the surface. I follow the steps using cloth to cover it and leave it outside. For the first day, it start bubble in it. It looks fine. Just right after this morning, it grow mold on the surface. What should I do? Discard it fully and make a new one or discard half of it and continue the process? Hope to hear from you as soon as possible. Thank you.

Rachael Dang


Rachael D. October 28, 2019
Hi, Stephanie B. I'm having another problem here about the volume of flour and water that I add into my starter after I discard 1/2 of it in every feeding, I'm not very sure whether I do it right or not. I use the method 1:1:1 ratio, its kind of slimy, slightly liquidity and has bubbles on the surface but the amount and weight of the starter together with the jar has been increased to 1,449g. It has milky smell and small bubbles on the surface as you've mentioned last comment. Due to the increased of amount, I've been changing the jar 3 times. I'm worried the amount is still increasing and yet my starter is not ready yet. Its been my 7th feed, 3rd day of 24 hours and it's still quite liquid. Even I did try the float test but it sink. So my question is my feeding is it correct? the latest flour and water that I added each is 237g. I feed it every 12hours. The starter with the jar is 1214g. The empty jar is 740g. Please advice. Thank you.
Rachael D. October 22, 2019
Thanks for your answer. I was misunderstood the instruction of the preparation for making a sourdough starter. The notes written on 1st steps "Stir together 60g flour and 60g water to form a thick and sticky mixture with no lumps remaining. Cover loosely with cheesecloth or a clean towel and set in a warm location for 2 to 3 days or until you detect a light, boozy scent and see bubbles breaking out the surface. Discard half and add another 60g flour and 60g water and stir to combine. Replace the cheesecloth and allow to ferment at room temperature for 8 to 12 hours. The mixture should be bubbly and active after this time." Is it means on the first beginning time of the 60g mix of each flour and water, allow it to sit for 12 hours, once we see life (the bubbles), we need to start the 1st feeding already. But is it means also we need to discard half of the starter and add or we just directly add in another 60g mix of each flour and water? Please guide and help me to be able to understand more the theory of the sourdough starter. Thank you for your speedy reply.
Stephanie B. October 22, 2019
In response to your question under my first comment: No, I don't think is not proper feeding or misunderstanding the instructions. I think 3 days might be too long to leave out the starter, especially if you're in a warm and humid environment.

Yes, you need to discard half the starter every time you feed it. It's a little wasteful, but once your starter is healthy and active, you can find recipes to use up this "discard" instead of throwing it away. But while you're getting your starter going, throw away half when you feed it. If it helps you any, when I started my starter, it smelled pretty weird the first couple of days. When it's healthy and ready to bake with it should smell a little boozy (like the recipe mentions) and fruity, and have some nice, larger bubbles. But before it reached that stage, it was bubbly (with lots of small bubbles) and smelled less fresh, more cheesy for the first few days.
Stephanie B. October 22, 2019
If the mold is only on the top, you can skim it off, discard a good portion of the starter beneath it, and using a clean utensil move some of the uncontaminated starter to a new container and carry on with that "clean" bit. But since you're just starting your starter and there probably isn't a strong microbial community yet, I'd just start over.

I notice these instructions have you leave your starter untouched for 3 days, that might be enough time for mold to grow undisturbed, and since you don't have lots of active microbes yet the acidity of your starter is probably not enough to inhibit the mold growth. There are so many recipes and instructions for getting a starter going, if one doesn't pan out try another. I had good luck with instructions from King Arthur Flour (, and once a day (not two a day) feedings. Getting a sourdough starter started (sorry if that sounds confusing) is the trickiest bit, but once you get it going it's very forgiving - if you can hang in there the first week or so it's so worth it!
Rachael D. October 22, 2019
Yes, Stephanie B. I left my starter untouched for 1 day 18 hours because I thought that the instructions said that after the mix of 60g flour and 60g water let it sets for 2 to 3 days before we start the first feeding. The first 12 hours to 24 hours it was okay, there's bubbly inside the starter and has the some breaking up to the surface. So is it my failure due to not feeding on proper time?
Recommended by Food52