How to Feed Your Potato Starter with Real Potatoes

If you’ve been working with a potato flake sourdough starter, you’re probably familiar with the typical feeding ingredients: instant potato flakes, white sugar, and warm water. But if you’re ready to take a more natural, from-scratch approach—one that skips the instant flakes—you’re in the right place.

Good news: you can feed your potato sourdough starter with real mashed potatoes! Not only is this a great way to use up leftover potatoes, but it also creates a healthier, more traditional starter that fits perfectly into a homemade lifestyle.

I should mention that while most potato flakes include additives, I’ve found one brand that keeps it clean: Bob’s Red Mill. Their package of potato flakes contains just one ingredient—dehydrated potatoes. Still, using real mashed potatoes gives you even more control over your starter recipe.

In this post, I’ll show you exactly how to feed your starter with real potatoes—without losing that bubbly rise or sour taste you love.

Why Use Real Mashed Potatoes?

Feeding your existing starter with mashed potatoes is a great option for those looking to avoid processed ingredients. Here are some other benefits:

• Fewer additives – No preservatives or flavorings like some tablespoons of instant potato flakes contain.
• Richer flavor – The natural sugars in real potatoes help your starter recipe develop deeper, more complex flavors.
• Ingredient control – You choose the potatoes and the process—ideal if you’re concerned about pesticides or GMOs.
• Budget-friendly – A bag of organic potatoes typically costs less than a comparable package of active dry yeast or organic potato flakes
• Accessible Option – Not all countries have instant potato flakes, but I’d say all countries probably sell or grow potatoes. Using real potatoes is a great option for anyone, anywhere. 

Old-Fashioned Way: Real Potatoes

The potato flake sourdough starter we use today is a modern twist on something that’s been around a long time. Before instant flakes were ever on store shelves, families made their own starters using real mashed potatoes, the starchy potato water left after boiling, a little sugar, and sometimes flour. They’d stir it all together and set it in a warm place, giving it time to bubble and come to life with wild yeast and good bacteria.

This early method didn’t rely on a package of active dry yeast or commercial shortcuts. It was just simple, homemade goodness—made with ingredients already on hand and a little patience. People kept their starters in a glass jar or glass bowl, and passed them down through generations. That original starter recipe produced bread with a soft crumb and a mild, slightly sweet taste—a truly delicious bread that’s stood the test of time.

While today’s potato flake sourdough is a more convenient method (especially if you’re a busy mom like me!), it still carries on that legacy. So the next time you’re feeding your own starter or baking up a batch of rolls, remember—you’re part of a long line of home bakers who’ve been nurturing these living things for generations.

Feeding with real potatoes isn’t such a new idea, rather just a way to get back to our roots. Nothing is wrong with using the instant potato flakes, I do it all of the time, but there is another way, that’s been around longer than we’ve been alive!

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Ingredients for Feeding with Real Mashed Potatoes

Find printable instructions at the bottom of the post!
Here’s what you’ll need for each feeding (about once every 5–7 days):

• 1/4 cup plain mashed potatoes (skin removed, unsalted, organic if possible)
• 3/4 cup white sugar
• 1 cup warm water (filtered is best)
• 1/2 to 1 cup of the starter (glass jar or glass bowl recommended)

Helpful tip: Make sure the mashed potatoes are completely cool before feeding. Hot potatoes can kill off the wild yeast and good bacteria in your young starter.

How to Make Plain Mashed Potatoes for Starter Feedings

Boil 1 medium potato (peeled and chopped) in water until fork-tender. Drain and mash until smooth—either by hand or in a large bowl with a mixer. Don’t add any milk, butter, or salt. Just potato!

Let it cool completely before using it to feed your starter.

Feeding Instructions (Using Real Mashed Potatoes)

1. Combine the ingredients
   In a glass bowl or jar, mix:
   • 1/4 cup mashed potatoes
   • 3/4 cup sugar
   • 1 cup warm water
   • Stir until smooth and the sugar dissolves.
2. Add to your starter
   Mix this into 1/2 to 1 cup of the starter from your original starter batch.
3. Let it sitCover loosely with a lid, tea towel, or plastic wrap and place in a warm place (like on top of the fridge) for 8–12 hours. You’ll know it’s ready when your bubbly starter is active, has risen, and smells pleasantly tangy.
4. Refrigerate or use
   Use it in your favorite potato flake sourdough bread, dinner rolls, or even cinnamon rolls! If you’re not baking right away, store it in the fridge and feed again in 5–7 days.

A Few Tips for Success

• Stick to a schedule – Feed once every 5–7 days if refrigerated. Regular feedings = good rise and consistent results.
• Keep your mashed potatoes plain – No butter, cream, or salt.
• Don’t panic if it separates – A little liquid (called “hooch”) is normal. Just stir it in or pour it off before feeding.
• Discard before feeding – Always reduce your amount of starter to 1 cup or less. Use the discard in discard recipes like pancakes, white bread, or cake recipes.

Can I Use Leftover Mashed Potatoes?

Yes—but only if they’re plain and unsalted. If your youngest daughter helped make mashed potatoes and snuck in butter or cream, skip those for your starter recipe. Extra fats can disrupt the fermentation and encourage unwanted microbes.

TIP: The next time you plan on making mashed potatoes, just double the amount and set aside some mashed potatoes for your starter, before adding anything into them.

Adjusting to Real Mashed Potatoes

Your starter might behave a little differently when switching from tablespoons potato flakes to fresh mashed potatoes. That’s normal!

It might take a second time or even a few feedings for your starter to fully adapt. You may not see as much foaming at the top like with flakes, but listen closely—it should have bubbles and make a soft fizzy sound. That’s a sign of a healthy, living thing full of good bacteria.

How to Freeze Mashed Potatoes for Starter Feedings

If you’re using real mashed potatoes to feed your starter, consider making a larger batch and freezing it in portion-sized amounts. That way, you’re always ready for a quick and easy feeding—no boiling required!

Find printable freezing instructions at the bottom of the post!

Freezing Instructions:

Make plain mashed potatoes
Boil peeled potatoes and mash them without any salt, butter, or milk—just plain potato. An easy way to mash them quickly is to put them in the stand mixer and use the beater attachment to mash them quickly. 

Cool completely 

​Let the mashed potatoes cool to room temperature to avoid trapping steam (which causes ice crystals).

Portion out
Scoop 1/4 cup portions into freezer-safe containers, silicone muffin molds, or ice cube type trays. You can also freeze them in 1-2 tablespoon size portions if using an ice cube tray. After the portions are frozen, you can place them in a bag for bulk storage.

Label and freeze
Write the date and quantity on each container. Store in the freezer for up to 3 months.

How to Thaw and Use for Starter Feeding

When it’s time to feed your starter:

1. Remove one 1/4 cup portion from the freezer (or more if feeding double or triple.) 
2. Place the frozen portion in 1 cup of hot water until thawed.
3. Once softened, add the 3/4 cup of sugar for the feeding into the water and mashed potato-water mix. 
4. Stir to combine. Ensure that the mixture isn’t warmer than 100F and proceed with your feeding as normal.

Note: Be sure the potatoes are not hot when you add them to your starter—just warm or room temp. High heat can damage your wild yeast.

Easy Thawing Tip:

You can also thaw mashed potatoes overnight in the fridge if you’re planning ahead. Just add them to 1 cup of warm water to increase the temperature a little before mixing with sugar and feeding your starter.

Why Real Mashed Potatoes Are a Healthier Choice

One of the biggest perks of switching to real mashed potatoes for your potato sourdough starter is having complete control over the ingredients—especially when it comes to quality and sourcing.

Potatoes Are on the “Dirty Dozen” List

Potatoes consistently rank high on the Environmental Working Group’s “Dirty Dozen” list, which identifies the produce with the highest pesticide residues. Conventionally grown potatoes can carry residues from multiple pesticides—even after washing and peeling.

When you use instant potato flakes, you may not always know where those potatoes came from, how they were processed, or what kind of chemicals they were exposed to. Some brands don’t specify whether their products are non-GMO or organic.

The Organic Advantage

By feeding your potato flake sourdough starter with real, organic mashed potatoes, you’re giving your starter (and eventually your bread) a much cleaner foundation.

• No synthetic pesticides or herbicides
• Non-GMO and minimally processed
• Better for gut health and fermentation
• Safer for everyone in the family, especially kids

Not only are you avoiding unwanted chemicals, but you’re also preserving the natural integrity of the fermentation process. Your starter thrives on whole, clean ingredients—so giving it organic, real mashed potatoes is a nourishing choice that aligns beautifully with a from-scratch, homestead-inspired lifestyle.

PIN for Later and Share with a Friend:

Switching to real mashed potatoes is a simple and rewarding upgrade to your own starter. Your original potato flake sourdough starter will thank you by giving a great rise, rich flavor, and bakes that make you proud.

So go ahead—boil that potato, mash it, and feed your happy little jar of potato sourdough starter. Whether you’re baking sweeter bread loaves, sourdough dinner rolls, or your favorite multigrain bread recipe, you’re taking a delicious step back to tradition.

If you decide to try it out and feed your starter with real potatoes, I’d love to hear all about it/ Please come back and leave a comment. I would greatly appreciate if you gave it a 5-star review! It helps me out so much! 

I also love seeing all of the delicious creations you make! Share your photo over on instagram or facebook and give me a tag @littletennesseehome

How to Feed a Potato Flake Sourdough Starter with Real Mashed Potatoes

Here is how you can feed your potato flake starter with real potatoes!

Print Recipe Pin Recipe

Ingredients

  

• 1/4 cup plain mashed potatoes unsalted, no butter or milk, skin removed
• 3/4 cup white sugar
• 1 cup warm water filtered preferred
• 1/2 to 1 cup of potato flake sourdough starter in a glass jar or bowl

Instructions

 

• Peel and chop 1 medium potato.
• Boil in water until fork-tender.
• Drain and mash until smooth—by hand or in a mixer.
• Do not add milk, butter, or salt.
• Let cool completely before using.

Feeding Instructions:

• In a glass bowl or jar, mix: 1/4 cup plain mashed potatoes, 3/4 cup white sugar, and 1 cup warm water.
• Stir until smooth and sugar is dissolved.
• Mix into 1/2 to 1 cup of your starter.
• Cover loosely with a lid, tea towel, or plastic wrap.
• Let sit in a warm place for 8–12 hours, or until bubbly, active,

Notes

Tip: Make sure mashed potatoes are completely cool before using—hot potatoes can kill wild yeast and good bacteria.

Print

How to Freeze Potatoes for Feedings

Here is the easiest way to always have potatoes on hand for feeding your starter.

Instructions

• Make plain mashed potatoes (no salt, butter, or milk).
• Let cool to room temperature.
• Portion into 1/4 cup servings using silicone molds or ice cube trays.
• Freeze, then transfer to labeled storage bags.
• Store for up to 3 months.

To thaw and use:

• Place 1 frozen 1/4 cup portion into 1 cup of hot water until thawed.
• Add 3/4 cup sugar, stir well, and let cool to under 100°F before feeding starter.
• Bonus Tip: Thaw overnight in the fridge and mix with warm water the next day.