I checked around on GW and apparently this is not uncommon. Will just go and get some ant poison I guess.

Over the last few years, I have had ants get into my pots both with dead plants and also with live plants. It's very frustrating. They tend to kill the plants. I tipped out a pot that was doing poorly and the bottom was filled with ants. I dumped it and put ant granules on it to kill them then later potted it back up in good soil and it eventually was ok and started growing again. I asked around and found out that it would be ok to put that soil where I put the granules, into the compost pile. So I did and it seems to be fine because I've used that compost since then. I don't know anything to do to prevent it. You just need to keep a watch on it and perhaps always dump the potting soil out when a plant dies into a bucket or some such so it's not tempting to them.

I saw several suggestions on another forum. The ants in my containers aren't just at the bottom of the container though. They are all through it. And, when I take the plant out; obviously, the soil just falls off around the roots...normally that would maybe be a good thing, but in this case the ants are creating huge air pockets which is not good. When I turn the plant over and take it out, it is as if I've picked up a giant ant mound and turned it over. It is awful.

We have had trouble with ants in some of our containers, especially the ones left outside all year. I think it is because most container planting medium tends to promote quick draining and air circulation, and some ants love to build nests in that type of environment. I saw something on Walter Reeves show a few years ago where he suggested a possible solution was flooding the containers with water. He said ants hate water flooding their nests and if you make the environment unfriendly they will move out. If the container has good drainage, flood the container till the water runs out the bottom. So I tried it and it worked. The ants hate the water and will quickly try to move all their eggs to the dry surface. The thing is you have to flood the container a few times before they decide to move on (I think I flooded several days in a row), and you have to continue doing it periodically or another group will take up residence. Also, the container must drain freely so you don't drown the plants roots and kill it.

opal -- That's a good suggestion and I saw a related one on another forum, where they actually suggested to take the whole container and literally submerge it in a big tub of water (holding it down with a brick or two). I am wondering now, how to keep it from happening to new plants I put out this year.

opal -- I was also wondering if whatever potting medium used is actually attracting the ants? That's what I initially thought, the first time, when it was shrubs from a nursery. After all, they'd only been on my driveway for four days. (Not that ants couldn't move in that fast...they certainly could.) But, I thought it was kind of fast for them to become the solid mass of ants that they were (with no mound on the surface). But, then when it happened to my containers (that HAD been out for a long time), I thought maybe it's just the area where I live. Now that I think about it, a related incident happened to me the first year we did tomatoes at our first house. I was standing in the bed, turning ground over, and before I knew it, my feet were covered in ants. (LOL I started RUNNING boy...but that's a funny story for another time.) Someone told me later that they were "ground ants." (I thought all ants live in the ground???) And, that I should treat any new veggie bed for ants, because in Georgia, we just have that problem more than in other places. But, wouldn't an ant poison be an unhealthy way to start out a veggie garden?

GirlGroupGirl might have an answer to this one...GGG, if you are around, will you weigh in on this? Have you had this problem before and, if so, what did you do about it? And, what can I do to prevent it?

Ant colonies can pop up anywhere near a food source and a suitable dry nesting area.
For many years I had no problem with ants in pots or in the garden, then a former resident across the road from me, began purchasing potted plants by the carload from a local nursery. Her property became infested with the hitchhikers and she resorted to a very strong pesticide for control and elimination. Where did they escape to? My garden, of course!
I use the dunk method for potted plants and then repot the plant with a new pot and soil. Mounds that are distant from plants are treated with boiling water. Several methods can be used around garden plants; corn meal, rice, chili pepper, etc.
Here's a link that discusses several successful biofriendly methods. I have never used tobacco and wouldn't recommend it, because it is toxic to some plants. Smokers that handle young, tender plants without sanitizing their hands first, can kill them.

Here is a link that might be useful: Kill Ants Without Pesticides