Ummm well, I don't think I would want to grow my dahlias inside. You may want to start them in pots under lights inside early....then transplant out to the garden. For me in zone two, I plant the clumps of tubers in the ground in May.......in your zone you could probably plant them right in the ground in April. Just watch that the ground isn't too wet. Unless you want to buy and plant new tubers each year.....then you would lift them out of your garden at the end of the season. This is done after your first frost and leaves are all brown/black. You would just cut off the stems 4 to 6 inches from the top of the tubers. Then just follow the directions that are on this forum for storing for the winter.

Happy gardening,
Sierra

I think what you really mean to say is that the bulbs cannot overwinter in the ground in your zone. They will grow beautifully for you, because they do for me. You just have to dig and clean off and store the tubers inside each winter. I put mine into plastic grocery bags and store them in my garage. As Sierra said, I sometimes start mine inside to get earlier blooms, but you probably won't even have to do that much! I agree with her, though, a dinnerplate dahlia inside probably isn't a very good idea.