7 Myths About Baking Soda and Hydrangeas You Need to Stop Believing

“I gave baking soda to my hydrangeas and they exploded with blooms!”

Ever heard someone say that? Or claim their sad, wilting shrub suddenly came back to life thanks to a sprinkle from the spice rack?

And the wildest one—baking soda turns hydrangeas blue. Yep, that’s going around too.

But here’s the real question: is there any science behind these tips, or are they just feel-good garden myths passed down like old family recipes?

Let’s take a closer look at 5 popular claims about baking soda and hydrangeas—and separate the real advice from the backyard folklore.

Myth 1 – Baking Soda Changes Your Hydrangea Flower Color to Blue

7 Myths About Baking Soda and Hydrangeas You Need to Stop Believing 1

Nothing could be further from the truth! While hydrangeas change flower colors according to soil pH (pink to blue and vice versa), to get the color of the sky you need acidic soil – and guess what? Baking soda is alkaline – the exact opposite (about 8.4).

So, will it turn them pink instead? Not really, unless you really use an awful lot, and then you may damage your hydrangea.

“Hold on, but they told me that it also depends on aluminum in the soil!” You are correct – its availability matters (and hydrangeas absorb more aluminum with acidic pH). But there isn’t a single trace of this metal in baking soda, which is made from sodium, hydrogen, oxygen and carbon (NaHCO₃).

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So no—baking soda won’t help your hydrangeas change color. In fact, it might do more harm than good. If you’re serious about shifting bloom color, skip the kitchen shortcuts and use proper soil amendments like sulfur or lime instead.

Myth 2 – Baking Soda Is a Great Fertilizer for Hydrangeas

It might be handy in the kitchen, but baking soda doesn’t belong in your garden beds—especially not as fertilizer for hydrangeas.

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Baking soda, or sodium bicarbonate (NaHCO₃), doesn’t contain the nutrients your hydrangeas actually need. Real fertilizers are packed with nitrogen, phosphorus, and potassium—the big three that fuel plant growth. Baking soda? It’s mostly sodium, and that’s not doing your shrubs any favors.

Sure, sodium is a micronutrient… in theory. But plants only need tiny amounts of it—if at all. And most soils already have plenty. Add more, and you’re asking for trouble. Too much sodium can throw off the soil balance, damage roots, and leave your hydrangeas with yellow leaves and stunted growth.

So if you’re thinking of giving baking soda a try as fertilizer, it’s better to skip pantry shortcuts and feed your hydrangeas what they really need: compost, balanced fertilizer, and healthy soil.

Myth 3 – Baking Soda Prevents Fungal Diseases Like Powdery Mildew on Hydrangeas

This one’s not a hard no—but it’s far from a yes.

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Baking soda does have some mild antifungal properties. It can make the leaf surface less welcoming for fungal spores, which might slow the spread of powdery mildew or leaf spot. But don’t count on it to fix an infection that’s already taken hold.

Potassium bicarbonate, which is closely related, has been tested on hydrangeas and does show some preventative benefits. But even then, results were limited—and when used in higher amounts, it actually harmed the plants. Popular varieties like ‘Nikko Blue’ were especially sensitive.

So while baking soda might help slow things down early on, it’s not a cure, and it’s definitely not risk-free. Too much can cause salt stress and hurt your plant. Better to rely on proven treatments and prevention methods like neem oil, proper spacing, and good airflow to keep fungal issues in check.

Myth 4 Baking Soda Keeps Aphids and Slugs Off Your Hydrangeas

I hate to break it to you, but this one’s pure garden gossip.

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Baking soda doesn’t do a thing to stop aphids or slugs from snacking on your hydrangeas. You could spray it, sprinkle it, chant over it—won’t matter. At best, you’re giving the bugs a light rinse. At worst, you’re wasting time while they keep nibbling away.

If your hydrangeas are under attack, you’ll need something stronger than kitchen chemistry. Go with pest solutions that actually work—and save the baking soda for your next batch of cookies.

Myth 5 – Baking Soda Can Revive Hydrangeas

We’ve all heard the tale—“My hydrangea was on its last legs, I tossed on some baking soda, and boom—it came back!” Sounds like magic, right?

Sounds magical, right? But let’s be real—it wasn’t the baking soda.

If your hydrangea perked up, it was probably because something else changed—maybe you watered less, the drainage improved, or it finally got the nutrients it needed. Baking soda doesn’t solve any of those issues. It doesn’t fix soggy roots, poor soil, or missing minerals.

So while it’s a nice story, it’s just that—a story. If your hydrangea is droopy or yellowing, skip the soda and check the basics.

Myth 6 – Baking Soda Kill Weeds Around Your Hydrangeas

Let’s cut to the chase: yes, baking soda can kill weeds. But should you use it around your hydrangeas?

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Ehh… probably not.

Baking soda might seem like a clever home remedy—cheap, easy, already sitting in your pantry. And yes, when dumped directly on weeds, it can dry them out and stop them in their tracks. But it doesn’t exactly have precision. It’s more like dropping a mini plant bomb.

The problem? It doesn’t stop with the weeds. Baking soda can also damage your hydrangeas. It builds up salt in the soil, messes with water uptake, burns roots, and—if you’re really unlucky—can even kill the plant you were trying to protect.

Plus, rain or watering can carry it to other parts of your garden.

So, is it worth it? Probably not. The weeds might go, but so could your flowers.

Stick with hand-pulling or mulching around your hydrangeas. It’s safer, cleaner, and you won’t lose your favorite blooms in the crossfire.

Myth 7 – Baking Soda Gives You Brighter Hydrangea Blooms

Want brighter, bigger hydrangea blooms? Baking soda won’t get you there.

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Flowering isn’t a magic trick—it’s about giving your plants exactly what they need. Hydrangeas depend on balanced nutrients like nitrogen, phosphorus, potassium, and micronutrients to push out those vibrant blooms. Baking soda (that’s sodium bicarbonate, or NaHCO₃) doesn’t supply any of these essentials.

Sure, baking soda contains sodium, but plants barely need it—and too much is actually harmful, stressing the roots and cutting down on flowering potential. The bicarbonate portion, which is just carbon, hydrogen, and oxygen, is already abundantly available from the air and water.

If you really want brighter blooms, forget baking soda and give your hydrangeas balanced nutrition, plenty of sunlight, and regular watering. That’s the secret to show-stopping flowers.

So, the Verdict: Is Baking Soda Good for Hydrangeas?

And the verdict is in… Baking soda is at best totally ineffective for these hydrangea problems and care. Excessive use can actually be noxious, so, better safe than sorry!

Amber Noyes

Written By

Amber Noyes

Amber Noyes was born and raised in a suburban California town, San Mateo. She holds a master’s degree in horticulture from the University of California as well as a BS in Biology from the University of San Francisco. With experience working on an organic farm, water conservation research, farmers’ markets, and plant nursery, she understands what makes plants thrive and how we can better understand the connection between microclimate and plant health. When she’s not on the land, Amber loves informing people of new ideas/things related to gardening, especially organic gardening, houseplants, and growing plants in a small space.

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