You aren't doing anything wrong; your plants are doing what comes naturally this time of year. Caladiums are one of those plants that require a dormant period, where they die down to their tubers, even when grown indoors.

Once the foliage dies down completely, remove the tubers from the soil and store in a paper bag in a warm dry place. (You can put vermiculite or something similar in the bag, or just store them loose.)

In late winter--early spring, pot the tubers up again, and begin watering. Your plants will come back to life.

I just bought a beautiful, full, caladium this spring (3 weeks ago), not time to go dormant. I have kept it inside near a south window except for one day when it was nice outside. I forgot to bring it in and the night temp. was in the mid 50's. Recently the older leaves started drooping, but not dying, and new leaves are opening. What am I doing wrong? What are the watering requirements? Thanks

Caladiums on the whole are tropical shade lovers, though a plant kept indoors would probably need more light than the plants situated in an outdoor bed, I would guess that the south window is a little heavy on the sunlight.

Being tropical, they also prefer moist, well drained soil. When getting more sun than is ideal, they would really need more water in order to recover.

Some wilt and drop of older leaves is usual through the growing season, but it sounds like your guy is getting sunburned.

I bought a caladium in April, and it had been doing great for a while in my west-facing window. All of the leaves curve toward the window and lean against the glass like little puppies looking out. When I got it, all of the leaves were around 10-12 inches long. All of the newer leaves are much smaller and the older leaves are starting to wilt. I used to have it on a cart with my other house plants, but I moved the others to another window when the caladium started looking crowded. It's in a deep 10" pot. About seven stems are wilted drastically, with 16 still standing upright. I water a few times per week with reverse osmosis, and it's in soil that claims to release water as the plant needs it. I give it a very diluted drink of Miracid about every 3-4 weeks. Is it normal in northern Illinois for the plant to start going dormant in July? What do I need to do for my plant? Should I cut off the wilting stems? Does it need different soil? Should I let nature run its course and just hope to do better next year?

Here is a link that might be useful:

plantsim it looks fine. It's normal for the old leaves to die off. When they start looking bad cut them off close to the new leaf stem that has grown out of the old stem. The reason the leaves are smaller is that you are growing it inside and it was probably raised in a green house where it would get more light.