Ant Colonies in my Pot Plants

August 16, 2007 7:09 PM

Why are there ants setting up nests in my pot plants?! Every time I water my lavendar, Geraldton Wax (Aust native) and my mint bush, ants start pouring out of the ground in their hundreds. I suspect they are also making the dirt in my pots 'hard' - the water seems to just run off it instead of soaking in. I have tried stabbing the dirt with a chopstick around the plants to airate the soil and get some water down to the roots, but the ants persist. Any help/ suggestions?
posted by gerls to home & garden (10 comments total)

Sprinkle cinnamon on the surface of the soil to kill the ants.
posted by mds35 at 7:20 PM on August 16, 2007

Antsand works at my place... though I suppose I'll try cinnamon this summer.
posted by pompomtom at 7:23 PM on August 16, 2007

if there is a lot of peat in your potting soil, and you let it dry out between waterings, the water will just run off the surface, and down the side of the pot. The quickest way to fix this is to submerge pot in a sink/tub full of water until air bubbles stop coming out. Or if you have the time, initially add a little water with a watering can, wait for it to soak in, then add a little more, repeat ad nauseum until water comes out the bottom.

This only works if you have a pot with a hole in the bottom though.
posted by ArgentCorvid at 7:34 PM on August 16, 2007

Ants don't like mint either, used to put it around my dog's food dish to keep them away.
posted by starfish at 8:11 PM on August 16, 2007

Most hardware stores sell some stuff I've used before that works really, really well. It's clear, thick sugar syrup with borax dissolved in it. You pour a puddle of it the size of a quarter on a piece of cardboard and leave it where the ants will find it.

They love the stuff, but it doesn't kill them immediately. The reason it's effective is that they carry it back into the nest and feed it to the queen, who is eventually killed by it. Without the queen, the nest dies. (The workers continue on autopilot for two or three more weeks.)
posted by Steven C. Den Beste at 8:40 PM on August 16, 2007

Also, diatomaceous earth. I've put in on and around house plants with good results. That doesn't answer the why of your question, though, for which I think the (not helpful) answer is that they like your plants.
posted by gingerbeer at 9:36 PM on August 16, 2007

The "hard" soil comment makes me wonder whether your soil needs wetting. Soaking it in a weak solution of detergent (biodegradeable) will make it less hydrophobic, and may therefore help with the ants.
posted by kjs4 at 10:58 PM on August 16, 2007

To answer the "Why": because they prefer it there. If the ground is too dry, they'll up and move house to somewhere moist. If the ground is too waterlogged, they'll up and move somewhere drier. With the dry weather recently, pot plants seem to meet their particular Goldilockian "just right" criteria.

They can be a PITA - I'm in a first floor unit, and a few months ago when the ground got really dry they decided to up sticks and emigrate to my pot plants - but they're also fascinating little buggers. For instance, about a week before there's any sign of rain, they'll up and move house again (usually to another damned pot!).

Ants Know Things...

(Unfortunately for them, and fortunately for us, they also seem to be slow learners. The "keep away from ant sand!" message is yet to sink in...)
posted by Pinback at 11:40 PM on August 16, 2007

Yeah, I find they do this because it's a nicely contained area that doesn't get walked on and gets a reasonable amount of water, and the dirt is nice and comfy.

The borax sugar (which you can do with Borax off the shelf and plain old sugar, put it in a little plastic lid or cap in the plant pot right after a good watering and then leave it alone for a couple of days) is probably as good as anything. It's good for roaches as well.
posted by Lyn Never at 6:11 AM on August 17, 2007

As mint likes really soggy soil I lined my mint pot with a watertight plastic bag and keep it saturated. It's thriving and I doubt wether ants would like to nest there.
posted by Dr.Pill at 8:26 AM on August 17, 2007