Zucchini & Walnut Sourdough Bread Recipe

Yes, another garden zucchini recipe. Sorry, not sorry. I don’t know about you, but by midsummer we’re drowning in the stuff! Even if you’re not in the same (zucchini) boat as us, this zucchini sourdough recipe is most certainly worth making!

This moist, fluffy, chewy zucchini sourdough bread is a healthy and savory twist on traditional zucchini bread. It is the perfect way to use up some of your excess homegrown zucchini, or simply inject more veggies into your life – which is always a good thing! It’s also much more versatile than sweet zucchini bread, and can easily be enjoyed on its own, as sandwich bread, or as a side with other meals. 

Before we get mixing and baking, I should note that this article will be most easy to follow for those who are familiar with making sourdough bread. Meaning, I am not going to go into extreme detail when explaining each step – such as “stretch and fold”. It follows the same process we use for our basic sourdough bread, but with a few tweaks along the way. Therefore, if you’re new to sourdough baking, you may find it helpful to check out this simple sourdough loaf recipe to get your feet wet first. And if you are in need of a sourdough starter culture, learn how to easily make your own from scratch here!


  • 295 grams of white bread flour, or all-purpose flour. We use King Arthur organic bread flour.
  • 140 grams of whole wheat flour. Bob’s Red Mill organic whole wheat is our go-to choice
  • 20 grams of rye flour. If you don’t have rye, simply increase the whole wheat amount by 20 grams.
  • 1 ¼ cup of warm filtered water
  • 120 grams of active sourdough starter
  • 1 to 1 ½ cups grated zucchini (see sliding scale info in directions below)
  • 9 grams of salt
  • ½ cup of walnuts – We use raw, unsalted, halves & pieces (substitute with unsalted sunflower seeds or pumpkin seeds for those with walnut allergies)
  • Optional, but delicious: 1/2 tsp of garlic powder and 2 tsp onion of powder

Timing: We generally make our dough over the course of one afternoon. This includes about 5 to 6 hours total, from initial mixing of the autolyse to forming into loaf that evening – with plenty of resting down time mixed in of course! We then let the dough cold proof in the fridge overnight, and finally bake it the following morning. 


1) Feed Your Sourdough Starter 

Wake up your sourdough starter and get it ready for baking! Feed your starter as you typically would, at least several hours before you wish to begin making dough. If you starter has been refrigerated, I recommend taking it out the night before and feeding it at least twice to reach peak activity. 

A two way image collage, the first image is a close up of the top of a flip top container sitting on a white plate. The lid is open which reveals a creamy whitish sourdough starter inside that has risen to the edge of the jar. The second image shows a blue spatula inside the jar, stirring the starter, it has many gluten strands that are stretching this way and that amongst many air bubble throughout.
Our sourdough starter, ready and active. I didn’t take this photo until we we opened it and added to the autolyse, on step 4 below!

2) Create an Autolyse

About an hour before you think your sourdough starter will be at peak activity and ready to use, weigh and combine the called-for flour and water in a large mixing bowl. Avoid adding cold water to the flour. Mix well – I use my hands! Let this mixture sit for an hour, covered with a tea towel. If possible, keep it in a location with an ambient temperature between 70-80 degrees Fahrenheit. The same temperature range is ideal for the bulk fermentation described below.

Note that this autolyse uses less water than our classic loaf recipe, and will likely seem more dry than usual. That is intentional! We need to scale back on the water here a tad, to compensate for the additional moisture that will be added to the loaf through the zucchini. 

A two way image collage, the first image shows a close up of the inside of a white mixing bowl which contains different types of flour, there is a measuring cup in the top right corner pouring water into the bowl, there is a stream of water and some of it is already in the bottom of the bowl, mixing with the flour. The second image shows the same close up of the bowl but now there is a formed dough ball that is whitish brown. There are air holes and gluten strands here and there.

3) Prepare the Zucchini

Once the autolyse has been mixed and resting for about 40 minutes, begin prepping the zucchini. It needs about 15 minutes of its own “rest time” before being added to the dough too!  Grate the zucchini into medium-fine shreds – we use a basic box cheese grater. Here is the note about the sliding scale: If you’re after a “taller”, open-crumb sourdough loaf, use closer to 1 cup of grated zucchini. We chose to use a heavier hand and go with 1.5 cups. It is zucchini sourdough bread after all! However, the additional moisture and weight from the zucchini makes the loaf slightly more flattened than our average loaves. We don’t mind. You can see from the photos that it is still plenty airy!

Add the grated zucchini to a strainer. Next, sprinkle the zucchini with a few light shakes of salt, and toss to mix. Rest the strainer in a very clean sink, or set it over a larger bowl. Over the next 15 minutes, the salt is going to help draw excess water out of the zucchini, which will drain away. To help remove even more moisture, I suggest tossing, pressing and lightly wringing out the zucchini every 5 minutes – a total of three times. Do not add the collected zucchini water to the recipe!

A two way image collage, the first shows a stainless steel strainer sitting on top of a white bowl whose outer rim is copper, the bowl also has two copper handles. Inside the strainer there is grated zucchini. The second image shows the same bowl and strainer, however, this image shows the strainer suspended above the bowl and to the front left corner of the image, there is a greenish liquid that covers the very bottom of the white bowl.

4) Combine to Create Dough

Now that the autolyse has sat for an hour, and the zucchini has weeped, let’s mix up our dough! In the bowl with the autolyse, add the grated zucchini, 9 grams salt, 120 grams of active sourdough starter, and if you have some, ½  tsp of garlic powder and 2 tsp of onion powder. The seasonings are from our garden as well. If you’re interested, check out these tutorials about how to make your own garlic powder and onion powder!

Thoroughly mix to combine all of the ingredients. Again, using your hands to pinch, toss, and knead will help accomplish this. Finally, give it a “slap and fold” to help further combine and tighten the dough. Place the formed dough ball in your bulk ferment container of choice. We place it back in the mixing bowl. Cover the container with a tea towel and let it rest for 30 minutes

A two way image collage, The first image shows a close up of the inside of a white bowl, there is a dough ball in the very bottom with pink salt, a light greenish powder, and a darker green powder in three distinct lines across the top half of the loaf, the bottom half of the loaf is covered equally by shredded zucchini on the lower left and sourdough starter on the lower right. The second image shows the same bowl but the dough and all the ingredients have been mixed thoroughly together leaving a formed but wet ball of dough.

5) Stretch & Fold + Add Walnuts

Next, it is time to add the walnuts. We do this during the first set of “stretch and fold”, which gives the walnuts time to become evenly distributed throughout the zucchini sourdough during the following sets. Add ½ cup of walnuts and fold it into your dough. See the video below for a demonstration!

6) Bulk Ferment

Continue bulk fermentation at room temperature for about 4 to 5 hours. During the first couple of hours, repeat at least 3 more sets of stretch and fold, about 30 minutes apart. Then let the dough rest and rise undisturbed for the remainder of bulk ferment.

7) Form & Proof

Now that your sourdough has finished fermenting at room temperature, it is time to get the loaf formed, tucked into its banneton (proofing basket), and put away to sleep in the fridge. On a lightly floured surface, form your loaf into the desired shape with a few folds and tucks. Afterward, we generally let it sit to bench rest for about ten minutes, give it one final fold and form, and then slip it into a floured banneton. Cover the banneton with a tea towel once again, and allow the dough to cold proof overnight in the refrigerator. 

The image was taken directly above the finished dough ball sitting in a banneton. You can see strands of green zucchini and chunks of walnuts throughout the brownish cream colored dough ball.
The zucchini sourdough, after the overnight cold proof in the fridge.

8) Bake 

Time to wake and bake! Preheat your oven to 475°F for one hour, with your empty cast iron combo cooker or dutch oven inside. After everything has preheated for an hour, carefully slip your cold dough straight from the fridge into the piping hot dutch oven or cast iron. For a smooth transition, we place a piece of parchment paper on top of the banneton, a cutting board on top of that, then flip the whole thing upside down. Out comes the dough ball. Give it a very light dusting of flour, and a fancy or simple score with your bread lame across the top if you wish, before easing it into your hot pan. Cover the pan with its lid, and get it into the oven.

Bake covered for 40 minutes, remove the lid and bake for an additional 5 minutes. 

Baking tip: Some people struggle with the bottom of their loaves burning. If you place a baking sheet on the empty oven rack below the one your bread is baking on, it helps absorb and deflect some of the heat. No more burnt bottoms!

9) Enjoy Your Zucchini Sourdough!

Once the loaf is finished baking, immediately (and carefully!) transfer your finished zucchini sourdough bread from the hot pan to a cooling rack. As difficult as it is to resist, allow the bread to cool for several hours before slicing into it. This prevents all that delicious moisture from escaping! Once it is cool, dig in!

Fresh sourdough bread is always best the day of or after baking. To store your bread, I suggest wrapping it in a lint-free tea towel before putting it inside a paper bag. That way, you can enjoy it over four to five days. However, if it becomes stale, you could also toast or broil it first!

We like to eat our zucchini sourdough bread much like we do any other sourdough bread recipe – any and every way! It is superb on its own, especially with those walnut bits and extra little spunk of garlic and onion goodness. We also like to pile on veggie sandwich toppings, like hummus or homemade “besto pesto“, tomato, cucumber, avocado, sliced radishes – whatever is available from the garden! Of course, zucchini sourdough would make an excellent side to any dinner meal, such as with soup, lentils, eggs, sautéed veggies, and more!

An image of 3 slices of sourdough bread displayed showing their insides. To the right of the slices there is the rest of the loaf of bread. There is a nice and brown crusty crumb showing on both sides of the bread and it is also littered with air holes, walnuts, and specks of zucchini.
A close up photo of a hand holding a slice of sourdough bread. It has humus spread over its surface and it is topped with three slices of red tomato and three slices of cucumber. The toppings have also been salted and pepper with specks of each showing throughout the slice. The background has a white plate with another slice of bread dressed in the same manner.

Ok guys. Finally, it is time for you to go make your own sourdough zucchini bread! But be sure to report back on how much you love it! Feel free to ask any questions, and spread the sourdough love by sharing this post. Pin it below!

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  • LucyD

    When adding “additions” is it always best to add them when adding the starter to the autolyse before various folds and bulk fermentation?

    • DeannaCat

      Hi Lucy – You can do it either way! I usually like to add herbs or seasonings (small stuff) in with the starter stage to let it all mix well. For larger chunky stuff (nuts, dried tomatoes, etc) I sometimes add them early, but most often add them during the first stretch and fold. That way, the starter has a chance to “feed” on primarily the dough for a good half hour and get happy before other goodies go in. I hope that helps!

  • Sarah

    Just tried this but added coco powder and chocolate chips for a double chocolate zucchini bread… will see what happens in the morning.

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