Can chilli powder really stop animals from digging up your garden?

If you have ever gone out and found your newly planted flower beds dug up or your vegetable garden ravaged, you will know my pain. From curious foxes to marauding squirrels, the destruction wrought by garden mammals on lovingly tended plants can be enough to test the patience of even the gentlest gardener.

That’s why garden centers are stocked with everything from ultrasonic devices triggered by motion sensors to creepy steel traps and even packets of dried lion droppings, all in an effort to protect your precious plants. But what if there was a cheaper, simpler, milder option that might already be on your spice rack: chili powder. Is this popular garden remedy too good to be true?

The idea is simple: Garden mammals respond to capsaicin, the spicy chemical in chili peppers, the same way humans do. When it binds to receptors in the mouth and skin, it causes that familiar spicy sensation that encourages them to avoid the treated areas.

You may be wondering why chili plants produce colorful, eye-catching fruits full of aromatic compounds, only to then associate them with this unpleasant-tasting molecule. Well, that’s because birds don’t have these receptors and are therefore immune to the effects of capsaicin. Researchers believe chili plants evolved the ability to produce capsaicin as a selective deterrent, discouraging mammals – which destroy chili seeds during digestion – while having no effect on birds, which shed the seeds intact.

Capsaicin is so effective at this task that it was added to birdseed to prevent it from being eaten by squirrels. It is also used to prevent rats and mice from eating poultry feed and has been shown to be effective in preventing rodents from eating wildflower seeds and destroying the nests of rare ground-nesting birds.

When it comes to larger mammals like deer and badgers, the results are less clear. A field trial conducted in the UK in 2005 found that although European badgers preferred baits without capsaicin, it did not stop them completely. They also haven’t learned to avoid it over time like other deterrents. This isn’t surprising, given that badgers are known to dig up and eat wasp and ant nests, so a bit of chili isn’t so off-putting.

Now let’s move on to nuance. What makes these trials difficult to compare is that they use different forms of capsaicin: pure chili powder, chemical coatings, or purified extracts. Additionally, although capsaicin is not water soluble, meaning it will not be easily washed away by rain, it biodegrades quickly, so multiple applications are necessary, especially since tolerance to its effects may increase with repeated exposure.

The main thing? Chili powder is a safe, natural and affordable way to deter mammals from your garden. Use the hottest type you can find, alternate its use to avoid habituation, and apply it only where needed. So save the rest for your kitchen!

James Wong is a botanist and science writer, with a particular interest in food crops, conservation and the environment. Trained at the Royal Botanic Gardens in Kew, London, he shares his small apartment with more than 500 houseplants. You can follow him on X and Instagram @botanygeek

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