How to evict ants from your garden if you don’t want to kill them

Daisy, the protagonist of Carol Shield’s wonderful novel The Stone Diaries, is for a time a garden columnist for her local paper. One very funny section of the novel is written as a collection of letters to Daisy. Some are from her readers, addressed to her pen-name, Mrs Green Thumb – it’s 1963. One correspondent notes that she much enjoyed Mrs Green Thumb’s dramatic struggle with the ant colony.

That caught my attention because I am currently battling an ant colony of my own. The ants have taken up residence in a big pot on the terrace.

You generally see ants in the garden where there are sap-sucking insects, such as aphids, scales and mealybugs. These insects produce a sweet, sticky substance called honeydew that the ants feed on. The ants protect their food source by preventing predators, such as ladybirds or hoverflies, from attacking the sap-suckers.

So the first thing to do when you see ants is to hunt for insect pests. Get rid of them and your plants will be healthier, with the happy benefit of inducing the ants to move along.

In this instance though, it’s shelter, rather than food, that has drawn the ants. Ants don’t nest where it is wet – quite the challenge this year – and this pot is under cover. It is home to a big alcantarea, which gets its moisture from the well in the centre of the plant, so there’s no need to water the potting mix.

Perfect, said the ants.

There are various ways to kill ants – you can bait them with diatomaceous earth or borax mixed with an attractant; or spray them with pyrethrum – but I don’t want to kill them. Ants have an ecological role to play in the garden, they pollinate some plants, eat the eggs of some insects, distribute some seeds, and are themselves a food source for other creatures. I just want them to move out of the pot and a bit further away from the terrace so they don’t run up my legs when I’m enjoying a sunset gin.

I tried a subtle eviction using the garden hose, but the potting mix has become hydrophobic and the water simply ran down the insides of the pot without wetting the mix. I needed a soil wetter to dissolve the waxy coating that builds up on organic particles when they dry out. I like Eco-hydrate but there are plenty of other options.