Delicious Sourdough Zucchini Bread Recipe (Optional Walnuts or Chocolate) 

Buckle up buttercup, because you’re going to love this sourdough zucchini bread recipe. Not only is it melt-in-your mouth tender and delicious, but the recipe is also very flexible and easy to customize! You can make our sourdough zucchini bread with discard or active starter, turn it into muffins, make it vegan, let the batter sit to ferment, or bake it right away. Keep it simple with zucchini alone, or add walnuts, chocolate chips, or other mix-ins to change things up! We’ve played with several variations – and they all turn out great.

With no refined sugar, no added banana or pineapple (apparently that’s a thing), this healthy sourdough zucchini bread recipe is as simple and pure as they come. Made with wholesome real ingredients, it’s less overpoweringly sweet than some other recipes out there – but no less delicious! Plus, I’ve included options to use whole wheat pastry flour (my favorite) which makes it even more nutritious. Not to mention this is a great way to use up extra zucchini during peak zucchini season in the garden!

Need a strong, established starter? We offer organic sourdough starter in our shop here!

Can you make sourdough zucchini bread with frozen zucchini?

Absolutely! When we’re harvesting more than we can eat fresh, we often grate and freeze shredded zucchini in one or two cups portions to later use in baked good recipes – just like this sourdough zucchini bread! Simply defrost the frozen zucchini before adding it to the batter, using the same called-for amount. I like to pull it out of the freezer at least a day in advance to defrost in the fridge. See more tips about freezing zucchini here.

Should I use active sourdough starter or discard?

You can use either discard or active starter to make sourdough zucchini bread. Using active starter (recently fed, used at peak activity) will result in a slightly lighter, more airy and fluffy loaf. We’ve also made this recipe using discard and it turned out great! It was a tad more dense and tangy, but not in a bad way. 

Note: by “discard” I mean you can use inactive, not fully risen starter. However, I don’t recommend using the first discard from a very old, acidic, neglected starter that hasn’t been fed in several weeks or longer.

Looking for other ways to use discarded starter? See our list of the 15 Best Sourdough Discard Recipes here.

Tips to make the best sourdough zucchini bread:

• Use standard-size zucchini to make sourdough zucchini bread, NOT massive overgrown garden monsters. Extra-large zucchini has a lower skin-to-flesh ratio and are usually more spongy, soft, and watery – and will offer less pretty dark green specs in the bread! Instead, use huge zucchini to make zoodles or this fiesta-style stuffed squash recipe.
  
  
• You can also make this recipe with other summer squash, such as yellow zucchini or yellow crookneck squash.
  
  
• Mix the ingredients in the order provided in the directions: wet, then dry, then zucchini and other optional add-ins.
  

• Use appropriate wet and dry measuring cups for the given ingredient. Also, it’s best to fluff and spoon flour into measuring cups and then level it off with the back of a knife – NOT scoop the measuring cup straight into the bag of flour, which can pack it too much.
  
  
• Use whole wheat pastry flour if you can! While you can make sourdough zucchini bread with all-purpose flour or white bread flour, I really love the slightly more tender, soft texture whole wheat pastry flour yields. Plus, it has more fiber and health benefits (e.g. lower glycemic index) than white flour!
  
  
• The batter texture should be thick, pourable, but not runny. Given the unique nature of baking with sourdough starter, you may find the need to adjust the consistency. Adjust the texture if needed by adding a couple tablespoons more flour (to thicken) or a couple tablespoons of milk (to make more thin).
  
  
• For added nutritional value, let the sourdough zucchini bread batter ferment awhile before baking (though not required). See fermentation time notes below. 

A note on batter fermentation time

Because this sourdough zucchini bread recipe uses both baking soda and baking powder, an extended fermentation time isn’t required to get a good rise (unlike most other sourdough bread recipes). Meaning, you can bake it right away! However, if you skip the proof and fermentation stage, you’re missing out on some added flavor and nutritional benefits. 

I personally like to let the batter sit for at least 4 hours (up to 18 hours) before baking. I’ve found 8 to 12 hours to be the sweet spot! This gives the sourdough starter ample time to interact and ferment the flour and other ingredients in the batter, while still yielding an amazing texture, flavor, and rise.

Yet because this recipe contains egg, the raw batter can only sit out at room temperature for up to 4 hours according to food safety best practices. So, either set your timer and bake it after 4 hours at room temp, or let it sit at room temperature for a few hours and then move it to the refrigerator for the remaining ferment time.  

Learn why fermented sourdough bread is healthier than other bread here.

Sourdough Zucchini Bread Ingredients

This recipe yields 1 standard size loaf (9×5” pan or or 8.5″ x 4.5″ pan), two mini loaves, or 12 muffins.

Dry Ingredients

• 1.75 cup whole wheat pastry flour. Okay to substitute with all-purpose or white whole wheat flour, though I found all-purpose flour made it a tad more crumbly.
• ½ tsp baking soda
• ½ tsp baking powder
• 1 tsp sea salt
• 1 tsp cinnamon
• ¼ tsp nutmeg
• Optional: pinch (⅛ tsp) allspice

Wet Ingredients

• 2 cups fresh grated zucchini (lightly packed, not wrung out). You’ll need about 1-2 medium to large zucchini. Yes, you can substitute zucchini with other summer squash (e.g. yellow crookneck).
• ½ cup real maple syrup*
• ¼ cup honey*
• ⅓ cup coconut oil or butter, melted. We’ve tried both, and while the difference is subtle, we prefer the flavor and texture of the finished sourdough zucchini bread made with coconut oil.
• ½ cup sourdough starter, active or discard – or approximately 100 grams. 
• 1 egg or egg substitute
• 2 tsp fresh lemon zest
• 1.5 tsp vanilla

Optional add-ins: ½ cup each of chocolate chips, dried fruit (e.g. raisins or cranberries), nuts or seeds like walnuts, pecans, or pumpkin seeds (pepitas). Pepitas can be used whole, but I suggest to lightly crush walnut or pecan halves into smaller pieces. If using walnuts alone (no other additions), feel free to add up to 1 cup. We love these organic semi-sweet chocolate chips.

*If you don’t have both honey and maple syrup, you can substitute and use just one (¾ cup total) but we really love the balance and flavor when using some of each.

Supplies needed

• Mixing bowls
• Measuring cups
• Cheese grater or food processor
• A standard 9×5 bread pan, or muffin pan. 
• Parchment paper (if your pan isn’t non-stick) or muffin liners

If you have any issues with the sourdough zucchini bread sticking to your pan, try our favorite non-stick USA bread pan instead. I can’t recommend it highly enough. It’s lined with food-grade silicone, making it totally nontoxic – and the bread literally slides right out! (We use this wide shallow version to bake our sourdough focaccia too).

How to Grate Zucchini for Bread

The easiest way to grate zucchini is with a box cheese grater. Simply cut off the stem and butt end, and shred away! You could also run it through a food processor. And no, unlike some other zucchini recipes, you do NOT have to strain or wring out the liquid from the zucchini! It helps make the sourdough zucchini bread perfectly moist as-is. Simply grate and mix into the batter at the end.

How to Make Sourdough Zucchini Bread

Instructions: Batter Prep

1. Whisk together the wet ingredients: melted coconut oil or butter, maple syrup, honey, vanilla, and lemon zest. (When zesting the lemon, try to get only the yellow portion of the skin, not the bitter white part.) Then beat in one egg. Avoid adding the egg directly into hot oil or butter.
   
   
2. Next, stir in the sourdough starter. Mix well.
   
   
3. In a separate bowl, combine and thoroughly mix all of the dry ingredients: the flour, baking soda, baking powder, salt and spices.
   
   
4. Slowly add dry ingredients into the wet bowl. Gently stir and mix only until combined. Do not over mix! A few lumps are okay.
   
   
5. Finally, fold in the grated zucchini along with any optional add-ins like nuts or chocolate chips. Again, avoid over-mixing.
   
   
6. Cover the bowl with beeswax wrap or a damp towel during fermentation to prevent the batter from drying out.
   
   
7. For the most nutritious results, allow the batter to ferment for 8 to 12 hours (though you can bake it sooner if you wish). Following food safety best practices, batter with raw egg should not be out at room temperature for more than 4 hours. So, we typically let the batter sit at room temperature for about 2 to 3 hours, then refrigerate it for the remainder of the time (usually overnight). For a shorter schedule, leave it out the entire time and then bake before the 4 hour mark.

Instructions: Baking & Storage

8. Preheat the oven to 350° F. Take the batter bowl out of the refrigerator and allow it to warm up at room temp for 30 to 45 minutes (while the oven is preheating).
   
   
9. Grease a 9×5″ bread pan with butter or oil, or line it with parchment paper like this.
   
   
10. Pour/scoop the batter into the greased pan and smooth out the top with the back of a spoon.
    
    
11. Bake the sourdough zucchini spice bread on 350° F for 60 to 65 minutes, until a tester (toothpick) comes out clean. Check the bread around the 40-45 minute mark and cover/tent with foil if the top is browning too quickly. Half loaves and muffins will take about half the time.
    
    
12. Allow the bread to cool for 15 mins in the pan. Then take it out and transfer it to a cooling rack.
    
    
13. Enjoy! This healthy sourdough zucchini bread is excellent on its own, but also pairs incredibly well with cream cheese.
    
    
14. The bread is best if consumed within 4 to 5 days. (Honestly, it’s even better on the second day than the first!) To retain moisture, store the bread wrapped, in a sealed bag, or in a food storage container with a lid. Refrigeration not required. You can also wrap and freeze leftovers for up to three months.
    

How to make sourdough zucchini muffins:

You can easily turn this zucchini sourdough bread recipe into muffins by following the same instructions , but divide the batter into a greased or paper-cup lined muffin pan instead. Bake for 25 to 30 minutes for standard size muffins and about 35 minutes for jumbo-sized. 

And that’s how to make delicious, healthy sourdough zucchini bread.

I hope you love this sourdough zucchini bread recipe just as much as we do! If so, please let us know in the comments and leave a review or rating. Please also feel free to ask any questions you may have. Otherwise, be sure to check out our other popular sourdough and zucchini recipes below. We even have another zucchini sourdough recipe to try: this rustic (not sweet) classic sourdough boule loaf with zucchini and walnuts. Enjoy!

Other recipes you may like:

• Healthy Sourdough Pumpkin Bread Recipe
• Sourdough Pancakes recipe (discard or active starter)
• Cinnamon Spiced Sourdough Chocolate Chip Cookies
• How to Make the Perfect Pesto Zucchini Zoodles
• Parmesan Zucchini Fritters with Healthy Dill Yogurt Sauce
• Basic No-Knead Sourdough Bread Recipe
• Simple Sourdough Focaccia Recipe
• Herb and Whole Wheat Sourdough Crackers
• Soft and Chewy Sourdough Ginger Molasses Cookies