Baking Soda in the Veggie Garden — Miracle or Myth?

There’s something about “old-school” garden remedies that I absolutely love.
The kind of tips passed down by oumas, neighbours, and that one uncle who swears he’s found the secret to the best tomatoes on the block. One of those golden nuggets that always pops up is baking soda — the humble white powder from your kitchen cupboard that’s said to do everything from curing powdery mildew to sweetening tomatoes.

But does it really work? Let’s dig in.

The Sweet Tomato Claim

You’ve probably heard this one before: “Sprinkle baking soda around your tomato plants and the fruit will be sweeter.”
I remember trying this years ago when we first started gardening — a light dusting around my tomato bed, hopeful that my cherry tomatoes would taste like little sugar bombs.

Here’s the truth:
Baking soda is alkaline, and the theory is that by slightly reducing soil acidity, the fruit becomes less tangy. But the reality? The soil’s natural buffering power and biological activity mean that baking soda has very little lasting effect.

Yes, it might temporarily raise the pH right on the surface, but it’s not enough to change the way your tomatoes develop sugars.
Sweetness comes from healthy soil, proper watering, and sunlight — not from a sprinkle of bicarb.

What Baking Soda Can Help With

That said, baking soda does have a few uses in the garden when applied correctly and cautiously:

1. Powdery Mildew Control
   A mild baking soda spray can help prevent or slow down early powdery mildew on cucumbers, pumpkins, and squash.

   • Recipe: Mix 1 tablespoon baking soda, 1 tablespoon vegetable oil or mild soap, and 4 litres of water.

   • Use: Spray lightly on leaves in the early morning (never in full sun).

   It works by making the leaf surface more alkaline, which makes it harder for fungal spores to germinate.

2. Fungal Prevention on Tomatoes
   For early blight or leaf spots, baking soda can act as a mild preventive spray — but it’s not a cure. I use it early in the season before heavy rain or humidity hits.

3. Cleaning Garden Tools & Trays
   Outside of plant use, baking soda is brilliant for scrubbing seed trays, pots, or even your garden gloves. It cuts through dirt and helps neutralise any fungal spores.

When Baking Soda Becomes a Problem

Here’s where I’m careful. Baking soda is sodium bicarbonate, and sodium is not something plants love. Too much can:

• Disrupt the balance of soil microbes.

• Burn tender leaves.

• Lead to salt build-up in the soil, especially in pots or raised beds with limited drainage.

So while it can be a useful occasional tool, it’s not something I use regularly or recommend sprinkling straight onto the soil.

Better Natural Alternatives

If you’re after strong, healthy plants that naturally resist disease, focus on:

• Compost & worm tea – feed your soil, not your plants.

• Neem oil – for fungal prevention and insect control.

• African wormwood tea – our VanZylStead favourite for natural pest deterrence.

• Good airflow – spacing and pruning your tomatoes to avoid fungal build-up.

• Mulching – keeps moisture even and reduces splash that spreads disease.

Healthy, biologically active soil will always outperform a chemical quick-fix.

My Honest Take

These days, I still keep a jar of baking soda in the garden cupboard — but mostly for cleaning, or a once-off preventative spray when humidity spikes.

It’s a helper, not a healer.
If your plants are struggling, reach for compost, mulch, and balance before you reach for the bicarb.

Because the real magic doesn’t come from a packet in the pantry — it comes from the life in your soil and the love you put into it.

VanZylStead Tip

If you want to explore more natural garden remedies and see what actually works in South African conditions, our DIY Fertiliser & Pest Control eBook and monthly Digital Garden Magazine dive deeper into tested home-grown recipes — from comfrey and wormwood teas to garlic-chilli sprays and beyond.  Become a member here

Happy Gardening My Friends

Tash & Family