Read below on a very similar poster's problem.

I'd like to amend my post on that link to say, although deer chewed their way through my perennials last year, not one dahlia was touched. They even nibbled immediately adjacent raspberries and blueberries, left the dahlias absolutely alone (bless their little hearts!)

Here is a link that might be useful: Disappearing Dahlias Thread

Okay, the thing is the broken off stem and leaves are still there. I go out and find a wilted plant, not even moved out of place, when I lift it, it is completely broken/chewed off at the base. It doesn't appear to be chewed anywhere else. Almost looks like something/someone has stepped on it but I've got tomato cages around them so I don't think that's the case.

Could it be that they are too wet? Crown rot..

Cutworms?

Here is a link that might be useful: Cutworms

Rabbits do this in our garden if we don't put chicken wire around the whole field. They do it in the rose garden, too-- & look you right in the eye while they bite off a stem & leave it there, then hop away! I tried blood meal in the rose garden & that worked until the first rain & then they were right back at it but the big garden is just too big to do that so the husband puts 3' high chicken wire around it until the plants get a couple of feet high. They don't seem to like the plants after they get big-- too tough I suppose.

I'll bet you're right! I've seen cutworms (I've always called them roly poly's) in my garden before, but I have never had a problem with them destroying my plants. They didn't touch my zinnias that I had planted last year.

Now off to research cutworm control!

Thanks so much, this is a great forum!

Happy gardening! BTW- my windowbox dahlias are FULL of buds, I can't wait to see what my first dahlias ever look like. I feel like an expectant mother!