On a hot summer’s day, the last thing I want on my patio is a trail of ants – and, thanks to this one plant, it’s the very last thing I’ll get. This plant has a fabulously fresh fragrance that I adore but ants absolutely hate, so while the patio bathes in its glorious scent all summer, those pesky garden pests stay away. The tiny lilac flowers are pretty, too.

I spotted the ‘Keep Ants Away’ sign next to a small pot of European pennyroyal (Mentha pulegium) at a flower show last summer. My patio was then overrun with ants – my perpetually crumb-dropping kids were entirely to blame for the invasion – so of course I had to give it a try. Because I like to garden organically, I appreciate that this natural pest control method wouldn't involve using chemicals that might harm the wildlife in my backyard. And hey presto, it actually worked to get rid of ants on the paving!

I’m pretty sure my pennyroyal plant is also working as a more general insect repellent, too, because I’ve noticed far fewer mosquitoes around the patio. My hunch may well be right because its name hints of historical use as a pest repellent as pulex translates to ‘flea’.

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Why I Recommend Pennyroyal to Everyone

I can honestly say that European pennyroyal was an effective solution at getting rid of ants on my patio, and keeping these pests away. Apparently, its strong scent disorients ants' navigating systems. The aroma sits somewhere between menthol and eucalyptus, and reminds me of childhood days off from school, cozy on the sofa with a tissue of Vicks VapoRub under my nose. It’s the sort of smell that makes you inhale deeply and relax. It’s fresh, cooling, and a welcome addition to a hot patio on a summer's day.

Since I added this plant to my patio, I haven't seen any new mounds of sand caused by ants burrowing beneath the paving, either.

European Pennyroyal is a Better Ant Repellent Than American Pennyroyal

The European pennyroyal is Mentha pulegium, not to be confused with the American native pennyroyal, Hedeoma pulegoides. Both contain the compound pulegone, which is effective at repelling insects, but concentrations are far higher in the European mint so it has a stronger scent.

Seeds of European pennyroyal are a little harder to get hold of but are available at the Seed Needs Store via Amazon.

The other benefit to Mentha pulegium is that it’s a perennial so you only need to plant it once for years of protection, while Hedeoma pulegoides is an annual so must be resown every spring.

Why You Should Grow Pennyroyal in a Pot

European pennyroyal is a member of the mint family so, just like any other mint, it's best to grow it in a pot because it can rapidly spread when planted in the ground. It’s a low-growing plant, only reaching up to a foot high, and needs a container at least 12 inches in diameter – though Mentha pulegium can spread up to two feet in a larger pot, if you’d like. Because it’s a creeping plant, it will look fabulous spilling over the edges of a bowl planter such as this contemporary resin container from Amazon or an urn such as this faux-brushed copper planter, also from Amazon.

Bear in mind that this plant loves moisture and damp conditions so will will need regular watering – and the bigger the container, the less often you’ll need to irrigate. It’s happy in full sun or partial shade and is hardy in zones 5–9 although, by putting it in a pot, you can easily grow it in colder zones by overwintering the container in a warmer spot.

It’s also good to know that there’s a bigger cultivar of European pennyroyal called Mentha pulegium ‘Upright’ that can reach three feet high so, if you want to grow that, you’ll need a larger pot.

More Plants With Ant-Repelling Properties

How to Grow Pennyroyal From Seed

Sow European Pennyroyal seeds on the surface of moist potting soil, barely covering them with a very fine sprinkle of soil (use a kitchen sieve) as they need light to germinate. Keep the soil consistently moist and warm (at least 68°F) and they’ll pop up in 1–3 weeks.

Must-Know Pennyroyal Facts

This mint variety is not edible and, though it’s been cultivated for years as a herbal remedy, should not be eaten as it’s potentially toxic. Historical texts record its use as a contraceptive and abortive remedy, so pregnant women should avoid it, and it’s best to wear gloves when handling the plant.