My wife has some nice pansies in pots on our porch. Sadly, she has noticed that some ants appear to be harassing them, leading them to look dull and unhealthy.
Our old neighbor mentioned that he uses a very weak soapy water solution when watering, and he swears that it keeps the ants out of his plants… including tomato’s and such.
Is there any truth to this?
My wife is trying to avoid using a chemical insecticide, as our 2.5 year old son runs around on the porch as well.
Dish soap will kill them. Use a couple of drops mixed with water in a quart sprayer.
The organic solution:
buy an anteater
They could have a nest in the pots, but I’ll bet they are going there for water. A next in a pot would be bad enough to kill the plants, otherwise I’d say they aren’t the problem. Pansies flower great starting early in the year. They then get tried out after growing for a few months. They may be to the point where it’s time to replace them with something fresh and she can cut them back to a couple inches and let them regrow. Pictures would help greatly, but I suspect that they are just entering that phase where they give out.
My carpenter plants (Silphium perfoliatum L.) were getting eaten alive by red aphids this year, so I decided to try an insecticidal soap on them. Went to the garden center, and they wanted $14 for a quart of solution in a hopelessly overorganic looking plastic spray bottle, so I decided to make my own. Based on a couple of recipes, I added 1/2 cup palmolive diswashing soap and 1/3 cup cooking oil to my hose end sprayer, and set it to come out with about 5 gallons of water.
It killed the aphids dead, and the plants are now all clean and happy.
Ants are a little tougher than aphids, so you might want to up the soap a bit. The recipes call for 1-2 tablespoons of soap per quart, my mix was juat a bit over one.
The commercial soap contains rosemary oil rather than sunflower oil, so it might be a little more effective, but the 5 gallons I used would’ve cost me $280, and I’d have gotten hand cramps from the little sprayer thingy. I’ll take the cheap stuff any day.
I have used Squink’s soap/oil/water concoction with success. I would also use some ant bait to decrease the population size. Terro works great, and is relatively safe when used as directed.
If you had aphids, the ants may well be “farming” them for their sweet excretions. Now that the aphids are gone, so will the ants, unless the ants bring some more in.
Yes, I’d check the plants over carefully for tiny soft-bodied pale yellow or greenish aphids. A weak soap/dishwashing detergent solution sprayed on the plants (go especially for the undersides of leaves and the newest immature growth) will kill the aphids, though you probably will want to repeat sprayings every week until the problem is under control. Aphids reproduce at a fantastic pace, so even a few leftovers can repopulate in a hurry.
The ants will likely leave once the aphids are gone, though a few species (i.e. fire ants) like to nest in pots and can damage plants if they do enough excavation.
Wasn’t “Sweet Excretions” a song by Aerosmith? 
Do ants actually eat plants? I would have thought that the ants were an indication of aphids, and the aphids were eating the plant.
How does the soap affect the pH of the soil, and how does this affect the plants? Are there varieties that the soap/oil combo should not be used on? Does this recipe work for other kinds of bugs besides ants/aphids?
Most liquid dish soaps are pH neutral, so there’s little effect on soil pH. The powders used in electric dishwashers are often basic. I wouldn’t use use them because they’re likely to burn plants. Most cooking oils should be OK to use. I’ve seen preparations containing corn, soybean, cottonseed, rosemary, neem etc. Stay away from the drying oils, like flax, unless you want your plants varnished.
Soap is hardest on soft bodied insects, but it does seem to annoy most bugs. Adding garlic, rosemary, mint, marigold, or cayenne to the mixture will make sprayed plants repellant to some bugs too.
