I have a coworker who uses ammonia - about a cap per gallon and waters well once with that. I tried it on some indoor ficus and it didn't hurt the trees. It also didn't totally fix the ant problem, but they were repeatedly coming inside from outdoors.

Boric acid laced baits are very effective at ridding a whole colony of ants. Boric acid powder could be sprinkled outside of your container, but it is not good for the soil (or plants growing in the soil). That's why the pre-mixed baits might do the trick for you.

I don't have any good ideas about how to PREVENT ants from colonizing your large containers...but I am sure that others will! ;-)

Find the place they enter the container and wash the area with boiling water, let it dry for about 2 min. then more boiling water, let it dry and then more water but be careful dont get the water in the pot or on the plant, after 3 times the ants usualy move on. If not get some amdro and sprinkle it on the ground around the pots.that wont get on your plants.

I've never heard of the boiling water concept. Wonder why that is purported to work? I ditto the use of Amdro as a very good (outdoor) ant bait, but it is a chemical pesticide used as a bait. Alexandrarose prefers not to use chemicals, but I think she might be encouraged to place one boric acid bait container inside her wine barrels. Maybe?

The way the boiling water works is disturb the ants as they run out in the open use the water, about 2 min. later more ants run out so more water and this soon gets them looking for a safer place to live, works for me.

another thought - Alexandrarose, would you object to insecticides that are contained so that they don't come into contact with you or your plants and animals? If you wouldn't mind contained baits, the Combat ant traps are fantastic. They come in an outdoor version, that will withstand the weather, and are very effective. I think that any ants that are attracted to them will take the 'food' back to the queen, which will then kill the colony and head them off from your barrels.
If containment of the chemicals in the baits doesn't address your concerns, then maybe you will get good use of the silica idea and someone else will like this one.

what is the problem with ants? dont they aerate the soil for free and eliminate certain pests? not to mention free ferts

Ants, when they set up housekeeping in containers, can create air pockets around the roots. They can do this in the soil, too. They can also make tending to the plants difficult, depending on what kind of ant. I have no idea what you mean about 'free fertilizer', perhaps you could elaborate on that interesting concept, lol. I'm sure that you don't mean 'ant manure'.

They tend to protect some of the most troublesome of plants pests such as aphids and scale. Some ant species will also harm the plants, damaging fruit especially.

depending on soil type the added air pockets could be a blessing.

and while yes they do tend to facilitate aphids and scale some also kill large insects for their meat such as catepillar,grasshopper, and other crop damaging insects.

others are also great pollinators and seed dispersers. my greenhouse was pollinated by the fans and little ants alone.

I don't like ants just for the fact that they do harbor and nuture pests... they like the honeydew that is secreted from many pets. Anyway, Alexandrarose, one of the things that I do when I have an ant problem is mix some plain table salt with some cinnamon(I don't like to use chemicals either) and sprinkle it around the container(if the container is in grass or a flowerbed, you will want to move it to keep the salt from killing anything). I don't think this actually kills the ants, but they DO NOT like the smell and most will not want crawl over it. After a couple of applications(from being washed away), the ants seemed to move on elsewhere. Sometimes, you have to have some patients with this method, but it has always worked for me. I also use this method when I find them trying to make their way into our home since I have a cat and I know this will not harm her! Just makes her sneeze! LOL!!!

I use a couple of methods, When planting, I put 2 inches of DE in the bottom of the pot. Then, I use rocks, or the stoneware legs sold at nurseries, to prevent contact between the bottom of the pot and the soil. This has stopped them so far, and I have 8 large pots out in the yard.

I JUST WANT TO THANK EVERYONE FOR THEIR GREAT IDEAS, KEEP THEM COMING.
WITH MUCH APPRECIATION
ALEXANDRA

Capslock is anoying

You could try some diatomaceous earth, it does tend to get in the joints and cut them all up.