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Hardiness Zone: 9a
Jo from Louisiana
One of the best products I have found for keeping ants out of my flower pots (and my house) is diatomaceous earth (DE). Just sprinkle a tiny bit around the base of your pots or on the ants' "runs". It won't hurt your plants if you also want to spread a little on the topsoil.
I like DE because it is organic and it is safe. It contains nothing more than the powdered skeletal remains of tiny algae-like plants called diatoms (and maybe some water). DE is considered a mineral-based pesticide. It is made of up magnesium, silicon, calcium, sodium, iron, and several trace minerals. You can find it at garden centers, feed stores, and some health food stores, or order it online. DE is usually sold in 1-2 lb bags and has the look and feel of ground up chalk. I'm not exactly clear whether ants ingest it, or just perish as a result of coming into contact with it, but either way, it dries them up within about 30 minutes of exposure. The only caution about using diatomaceous earth is that you should not continuously breath any of the dust. Once you open the bag, you may want to store it in an additional bag to help contain the dust. I've used DE both indoors and out. I also have pets and have never had any problems, but like any pesticide, I restrict their contact with it. Always read and follow the label directions carefully.
Another organic method I've read about is scattering worm casings 1 inch thick across the topsoil of potted plants. Apparently, fire ants (and whiteflies) in particular don't care for this. I have not tried this method personally, but I like the sound of it. You are feeding your plants, while keeping troublesome bugs at bay. If you try it, let me know how it works. You can order worm casings online, get them from worm composters, or find them where organic garden products are sold.
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Here are questions related to Getting Rid of Ants in Outdoor Potted Plants.
How do I get rid of ants in the soil of my outside plants on my patio?
By Brenda C from Clinton, NC
I place my plants in a large saucer or tub containing about an inch of soapy water, then flood the potting soil with a soapy-water solution (a little Dawn dishsoap in water). The soapy water will kill the ants, which can't get away because of the water in the saucer/tub. When the ants climb up the pot or up the plant, I spray the soapy water on them. But don't do this in sunlight because it can burn the plants. After the ants are dead, I spray clean water on the plants to remove the soapy water. I've never had a plant die, and I put all my plants out in early spring, each year. Sometimes, I'll water my plants with soapy water just to make sure they don't contain any ants before bringing them in. It's a cheap solution to an aggrevating problem.
I have a large pot outside with several kinds of plants in it, I just discovered it is full of small black ants. When I moved the pot, the ant "holes" were all under where the pot has been sitting for quiet awhile. Does anyone know how to get rid of these little devils without killing my plants or having to dump the entire pot? Thanks, any help would be appreciated.
Hardiness Zone: 8a
By Harden from NC
I have had good luck with cinnamon. Just sprinkle it on top of the soil and they should leave.