Hi Cathy~Maybe you can place them against the house or some sheltered area. What about getting some hay bales and doing some kind of "mulch"? How hardy are they? Zone 4 or so? I ask that because if they can survive those temps in the ground then maybe they'll survive your temps above ground. Do you have a shed or an extra bay in the garage or room in the basement. Maybe you can put some in there, and then leave some outside, so if you do lose some, you won't lose all. Good luck!

Try wrapping the pots with those big christmas lights and leave them on when the temp drops below freezing. It may keep them a few degrees warmer and they may survive. You could also constuct a crude green house out of a plastic drop cloth and some scrap wood. Combine that with Christmas lights for added warmth during the really cold spells and you might get some that make it.
Jennifer

Placing them up against the south wall of your house may also help, Cathy. I'm leaving mine in pots (some) this winter, too, but I'm a bit warmer than you are in zone 6.

I've overwintered plants in my backyard (south facing) that were zone 7 (no colder than that) by placing them in a corner of my stockade fenced backyard. There is an oakleaf hydrangea close by, lots of trees, a shed, and they did fine. I also took some leaves and just piled them up on top of and around the plants. Since your milkweed is pretty cold hardy, I would think that would be just dandy! Just make sure they don't totally dry out for long periods of time. I don't think you'll have to worry about that in PA. Also, your snow cover and ice will insulate them as well.

Susan

Cathy; I was actually wondering what I was going to do with my 3 1 gallon swamp milkweed pots. I have a few potted perennials (hosta, chinese lanterns, platycodons) that have survived for years now. Even that late cold snap we had earlier this year didn't do them in, although it did do in a potted Rose of Sharon. The hosta and chinese lanterns are exposed on the deck, with no protection, but the platycodon I did put up against the house. As for my milkweeds, I have no place to plant them right now, and if they're going to remain potted, I'll probably bury the entire pot in my veggie patch. Otherwise, I'd prop them up against the house. I'm not big on mulching...

When I lived in WI, I had swamp milkweed in pots. I placed them in the garage for the winter and cut them down to stubs. Garage was not heated, but maybe 20 degrees warmer than outside. It did have a fiberglass door so left in some light. I had them for several years that way.

Thanks to all of you for your great suggestions. They're so good that I still haven't decided what to do. Ha. I wish our winters were a little warmer than what they are, but it does get pretty cold here. Some winters we have lots of snow and others we don't have much. When we get snow, sometimes it lays on the ground for weeks if the temps stay low enough, and sometimes it melts after just a day or two. It all depends how much snow we get and how cold/warm the temps are. I can't depend on snow cover for protection against the cold because it's not always there when the temps are real cold. I'm going to have a lot of pots to move closer to the house. I'll put as many as I can on the south side and when I run out of room there, I'll put the rest of the east side. I hope it will make a difference. Our back porch is on the south side of our house, so it's not like they will be getting any heat from the house. I hope that most of them make it over the winter. I just thought this would be easier than having to plant that many all over again. If I'd have to, though, I'd just keep the soil in the pots that's there already and plant milkweed seeds in the pots in the spring.
Cathy

Can I plant swamp milkweed in pots? I live in South Mississippi. I thought that they needed swampy areas to grow.

Yes, it's perfectly fine to plant swamp milkweed in pots. I put the plants in 3-gallon pots because I plan to keep them year after year (crossing my fingers that they make it above ground during our winters). The seeds need a period of cold, so you can either put them in the frig for awhile before planting in the spring or do what I did and plant them in pots in the fall and they will sprout in the spring. I'm not sure how cold it gets where you're at though. Maybe you'd have to put yours in the frig first if your winters don't get very cold. I know that ours get plenty cold.

I kind of wish swamp milkweed would have another name because for one thing, I think maybe people probably do assume that they need to be in a swampy area to do okay, but that's not true. They do fine in pots or in the garden. We had a drought this year and mine didn't die. Of course, I did water them occasionally just to make sure they pulled through. I'm talking about the 100 plants that I planted in a bed of their own. I just started them this year, so you'd think if they'd have died any year from the dryness, it would have been this year because of both their young age and the drought. Another reason why I wish swamp milkweeds would have a different name is because maybe people who aren't familiar with them hear the name and get a mental picture of some horrible-looking plant.

I would recommend not planting them in just one-gallon pots if you're going to let them grow and not cut them back at all. I had bought some in one-gallon pots at the nursery in the late summer of 2005 when I was just starting my butterfly garden and those plants were so tall compared to the pot and not much weight in the pots with just that small amount of soil that the plants/pots kept falling over before I got them planted in the garden.
Cathy