I have grown a couple of perennials in pots before. What I usually do is wait for the first killing frost to bring them into the garage. That way they are dormant. I very sporadically give them a little water during the winter, like maybe once a month. I wouldn't say that mine have gotten a head start, they usually start emerging the same time as most of my other plants. I have even done this with plants that are not for our zone and they have survived. Our garage isn't heated, but it is attached to our house. Good luck!

aka margo, What plants have you had luck with?

I haven't tried it except for hens and chicks. A friend who is a horticulturist said that it isn't the cold that kills the more tender perennials, but excess moisture. So in a way, keeping plants in the garage could be safer because you can control the moisture. I don't know, but the only way to find out is to try.

I have a few that will be going into the garage this winter; some mini evergreens, gaura, and a couple of others that I can't remember off the top of my head. I can't keep Gaura alive in the ground, so I am hoping I can keep it alive in the garage. Some of the evergreens are zone 4 and one is a zone 5. I don't know if the garage will make a difference or not, but I doubt the plants would survive the winter in the ground.

I too would be interested in hearing from others.

When I lived in Zone 4 (Near Eau Claire) We built a deck with large open boxes to put hostas in. We used large plastic tubs (14- 16 deep; abt. 24"X24"), planted hostas in them. Then when it got cold, we dug holes in the woods behind our house to sink the tubs in. In Spring we dug them up and put them back in the deck boxes. We did this for about 5 years, until we moved upnorth where we are now. We never had a problem with winterkill. I don't know if that would work with other perennials. Hostas are pretty tough.

If you are putting them in a garage they needn't be hardier than your zone. In fact, you may be able to overwinter zone 6 plants in your garage. The colder zone applies to containers left out above ground. I overwintered Hakonechloa macra 'Aureola' several winters in my garage in ceramic pots. That is, until the rabbits and my dogs mowed them down to nothing one year. (shrug)

tj

I keep Mums in pots right outside over winter and they come right back up. No need to stick them in the garage. Z5 here too.

I have overwintered Hydrangeas not for our zone in the garage. Also hostas, irises, dahlias, and this year I am going to be trying to overwinter heuchera (which should be easy since mine don't die off during winter that are outside in the ground).

I overwinter sepervivum (hen and chicks) outside in containers and it is definitely true that cold doesn't kill them, moisture does so I slide the pots under a table on my deck to shield them from most of the precipitation.

Vinca vines have overwintered well with no protection at all (I am zone 5, border of zone 4, last winter -20 was the low).

Columbine has also overwintered in whiskey half barrels with no protection and emerged almost under the snow.

Not perennials, but some annuals that reseed have overwintered in containers for me. Dill and blanket flowers (Gaillardia) are reliable. Technically Gaillardia may be perennial, but the plants don't survive (in containers), the seeds do.