The wikipedia article on dahlia says that they are perennial plants. However, the dahlia section at my local garden center claims (in their little info booklets) that they are annuals. Upon further research, I found that:
Generally, seed grown varieties of Dahlias are started as bedding plants and then treated as annual plants. They will produce tubers during their first year of growth which can be dug and replanted in the same way as larger Dahlias, but because of the ease of growing them from seed, most gardeners prefer to discard the old plants and start fresh the following year.
So, they're only treated as annuals and are not really annuals. This coincides with some other articles on the web that suggest removing dahlia tubers and storing them over the winter and replanting them in the spring (i.e., if you choose not to discard them) if you live in a cold place.
My question is: Will dahlias grow as perennials and not die if I just leave them in the ground? I live in SoCal and we don't have winters here.