Sourdough Starter Activation Guide

What You’ll Need

  • A clean jar or bowl

  • Clean, lukewarm water (filtered or purified if possible)

  • All-purpose flour

Day 1

Mix ½ cup lukewarm water with your starter powder and stir for about 2 minutes.
Add ½ cup + 2 tablespoons all-purpose flour and mix well.

You’re aiming for a thick paste consistency—add a little more flour if needed.

Cover loosely with cling wrap or parchment paper and place in a warm spot (like your oven with just the light on).

⚠️ Tip: Put a piece of tape over your oven controls so you don’t accidentally preheat it! Some oven lights can get quite warm (100°F+), so if that’s the case, place your starter on top of the fridge instead.

Day 2

Give it a good, vigorous stir.
Cover again and return it to your warm spot.

Important Note (For All Days)

Keep your starter thick—more like a paste than a liquid.
When feeding, always mix in water gradually and only add enough to maintain that consistency.

Day 3

You may start seeing bubbles and notice a slight sour smell.

Add:

  • ½ cup flour

  • Up to ½ cup lukewarm water

Stir thoroughly, cover, and return to your warm spot.

Day 4

Repeat:

  • ½ cup flour

  • Up to ½ cup water

Give it a stir—and yes, feel free to say something nice to your starter.
Back to its warm home.

Day 5

Now it’s time to discard half of your starter (yes, really).

Then add:

  • 1 cup flour

  • Up to 1 cup water

Mix well and return to your warm spot.

👉 Why discard? Your starter is full of hungry yeast and bacteria. Reducing the amount keeps things balanced and ensures they have enough food to stay strong and active.

Reminder: Keep it thick—it should still be slightly difficult to stir.

Day 6

Feed again:

  • ½ cup flour

  • Up to ½ cup water

Stir, cover, and place back in your warm spot. Stay patient—you’re almost there.

Day 7

Repeat the process: discard, feed, and wait.

🎉 Congratulations! Your starter should now be active.

How to tell it’s ready:

  1. You see consistent bubbles

  2. After feeding, it doubles in size within 6–8 hours

Final Notes

  • It’s normal for your starter to rise and then fall—that’s part of the cycle.

  • If it overflows at some point… welcome to the club.

  • Keep feeding it regularly, and it will only get stronger over time.