Can you use flour to deter garden pests? That’s the question everyone’s asking at the moment, thanks to some pretty bold claims on social media.
Honestly, every week it feels like the online masses find a new kitchen staple that’s apparently destined to become the next miracle gardening hack. I’ve seen cinnamon, banana peels, coffee grounds and baking soda all have their moment in the spotlight. Now, though, it’s the turn of plain old flour.
Video after video has shown gardeners dusting it over their plants, with some even sprinkling it across flower beds, claiming it keeps pests away without using chemicals. All of which sounds… well, highly unlikely. Then again, stranger garden hacks have turned out to contain at least a tiny grain of truth.
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So naturally, I did what I always do when the internet starts making bold gardening claims. I turned to my husbandwho just so happens to be an RHS-trained professional gardener with over two decades of experience under his toolbelt.
Can You Use Flour To Deter Garden Pests?
My moment of curiosity happened halfway through an episode of Taskmaster (you know how it is), which meant I paused the TV, asked whether I should start throwing flour around the garden, and was met with the sort of long sigh that suggested I had committed a cardinal sin by interrupting Greg Davies.
Once my husband had accepted that the episode wasn’t restarting until he’d answered my question, though, he admitted the internet wasn’t completely wrong.
“There’s a grain of truth to it,” he told me. “But it’s one of those hacks that’s been stretched so far online that people think it’s a miracle cure, when really it only has a very limited use.”
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According to my husband, plain all-purpose flour can sometimes help against small, soft-bodied pests like aphids, cabbage loppers, and some mites.
“The flour isn’t poisoning anything,” he explained. “It’s purely mechanical. When tiny insects feed on leaves coated with flour, the starch mixes with moisture from their mouthparts and digestive system, creating a sticky paste that makes feeding much more difficult.”
Eyes flickering between me and the paused television, he rolled his eyes as he realized I needed more. “It’s a similar idea to using food-grade diatomaceous earth as a physical barrier rather than a chemical pesticide,” he added.
(Image credit: Samuel Howell / Getty Images)
The important word there? Sometimes.
“It’s only really effective as a very light dusting in dry weather,” he said. “As soon as it gets damp, most of the benefits disappear.”
And this is where his enthusiasm disappeared completely, as my husband pointed out that flour is (whether we’d happily chow down on it ourselves or not) food. “If you’re scattering it around your garden, don’t be surprised if mice, rats or other hungry visitors decide you’ve laid out a free buffet,” he warned
Warming to his theme of ‘don’t you dare use flour to deter garden pests in our yard, Kayleigh’, he moved onto the not-so-little issue of the weather.
“If flour gets wet, it it turns into glue,” he said. “You end up with this sticky paste coating the leaves, trapping moisture against the plant. And that’s exactly the sort of environment fungal diseases love.”
(Image credit: Ratnakorn Piyasirisorost / Getty Images)
My husband also pointed out that flour washes away surprisingly quickly, which means you’d need to keep reapplying it after rain or even heavy dew.
“And if you get a bit overenthusiastic,” he added, “you can end up coating the leaves so heavily that you’re blocking sunlight and making it harder for the plant to photosynthesize. That’s hardly helping, is it?”
So if you can’t use flour to deter garden pests, what should you use instead? Well, his answer came without hesitation: food-grade diatomaceous earth.
“It works on the same basic principle, as it’s a physical barrier rather than a poison, but it doesn’t become a sticky mess or invite rodents into the garden,” he said promisingly.
Shop Essentials for Deterring Garden Pests:
Diatomaceous Earth
Food Grade Diatomaceous Earth
Diatomaceous Earth is a widely used physical barrier against crawling pests that doesn’t turn into paste when it gets damp (although it does need reapplying after heavy rain).
Garavigo
Durable Fine Mesh Netting
Fine mesh netting offers a simple way to stop cabbage butterflies and other pests reaching vulnerable crops in the first place, without affecting pollinators once plants aren’t in flower.
Clark&Co Organic
Live Ladybugs
Rather than trying to eliminate every aphid yourself, encourage the insects that naturally keep their numbers under control with pollinator-friendly planting and insect habitats.
For gardeners dealing with aphids, he also recommends starting with the gentlest solutions first, such as a strong jet of water, encouraging beneficial insects like ladybugs, or simply tolerating small numbers of pests where possible.
As is so often the case with gardening hacks, the viral version isn’t completely made up, but it usually leaves out the important part. In this case, flour can have a small (albeit temporary effect) on certain pests under very specific conditions, but it’s far from the miracle cure social media sometimes makes it out to be
Personally, I think I’ll save the flour for baking… and let my husband get back to Taskmaster in peace.
