I'm not much in favor of over wintering in containers, because some will suffer, it would be better if you could plant them permanent or bury the pots about half way
into the ground....or put them some place, where you will get more snow, like snowdrifts.
Konrad

some neat ideas, Glen. Thanks.

Mary, from Montreal, has an interesting theory of wintering in pots.

Here is a link that might be useful: Mary's idea of wintering pots.

Last year I had a few small plastic pots of mums that I placed in a protected corner and covered with plastic bags of leaves. When I uncovered them in the spring they had started some new growth but also had some mold on them. They overcame the mold and grew beautifully all summer. This year I tipped them and covered them with shredded leaves - no plastic.

What did you end up doing with your containers for the winter?

I do this every year with 3000 potted conifers.

These are in 2 gallon square pots. Pots are tapered, and about 6x6 at the top and 4x4 at the bottom.

Pots are set in rows of 6 as close as I can pack them. These are penned in with small square straw bales, also close packed. Old tarps are used to cover the top and windward side of the bales. Loose straw is used to stuff the bigger cracks.

When there is snow, I use the snowblower and cover with a foot of snow.

Oh yeah: water well the during the last week before the temps stay below freezing.

whatever method you use, the over-all goal is to keep the root ball in as steady a winter environment as possible. Out here, its the continual freezing & thaw during late winter/early spring that kills a lot of plants. If they thaw out and break dormancy, their sap starts to flow...which freezes, expands and breaks the bark and what not when a hard freeze comes back.

I lost 8 highbush blueberries and a 15yr old apple tree to our spring freeze/thawing a few years back when it was particularly bad and I had forgotten to cover the blueberries with fall mulch. The apple tree was just a freak of nature.

Snow makes a great insulator, if you can get the pot part covered by a snowbank they will stay in dormancy longer which is good, as they will stand a better change of not being hit with continual freezing & thawing during early spring.

Sherwood's idea sounds like a good one. I think I'll try it with some of my patio planters next fall. Beats having to burying them in the garden every October.

Whatever method you try, best of luck. I hope they all make it through for you.

When I gardened in zone 4/5 in Wisconsin I had several roses in pots and I overwintered them in my unheated attached garage. I had the floribunda Sunsprite in one pot or another since 1984. In November I would remove all of the foliage from the bushes and water the pots real well. After they drained I would slip the pots inside extra large 55 gallon black plastic garbage bags and fold the open ends over - dont' tie the bags shut, they need air. I found these large bags at farm and fleet type stores. Then I'd prop the bagged roses up off the cold cement floor. I used wooden boards or styrofoam sheets to place the bagged roses on. The plastic bags helped keep the potting mix just moist. Heck, the last 2 winters when we were snow birds here in FL I wasn't even around to water the pots during the winter! When I returned north the roses had begun to sprout. This new growth was pale and weak. I left them alone - unless they really needed water. When the forsythia bloomed I would take the roses out of the bags and into the sunshine and remove the pale sprouts. Then I'd water them real well. In a week or so new normal looking shoots would begin to appear. This was my sign to begin giving them regular care (fertilizer, etc.).

It also depends on what you grow in them. I have read that you need plants hardy to two zones colder than where you are, to leave them in containers all winter. I know from experience that lilacs and sumacs will survive in a container, unprotected, all winter in zone 5.

My question us also about overwintering plants. Lemon verbina, pineapple sage, and an unknown but very tender tropical. I live in a VERY windy and dry area. As I write it is blowing a pretty steady 50 mph and gusting well above that. No snow lives long here but in rare years. (Had 2 yrs. ago, spectacular perrenals!) No attached or slightly heated areas, and in 1/2 barrels or large pots so don't think burying is an option. To tender, I think, anyway. Have a heated garden room that I am keeping cool at present (right-wrong don't know, but it is where I start my seeds so it will soon be well lighted and warm. If I invest in full spectrum lighting will that make them sturdy if I cut them back and they start growing. I am at a loss.
Thank you so much for any help that you can offer.

I have 4 2 gallon pots with Miss Kim Korean lilac shoots from an established shrub.The shoots have all been in the pots from May of 2013. They survived the drought ridden summer here in Minnesota with occasional watering from my sprinkler system. My question: how can I winter these safely so I can transplant them when I move in the spring> I live in zone 3b in central Minnesota.

In your zone, I would try to overwinter them in an unheated garage or cold cellar. If you have to leave them outside, dig the pots in the ground up to their rims and cover with lots of mulch, leaves, etc, after the ground freezes. Any well-drained area that gets lots of snow cover sould be okay.

I have about 50 Peonies in 10-12-14 inch wide pots that we dug last fall and did not have time to give them away or plant them, the pots are at least 12 inches deep, some deeper, as these were large transplants.
The same problem happened last year and this method worked. We dug a trench about 14 inches deep and 14 inches wide or about those measurements. Large enough for the pots to sit in without being exposed. Now covered in and around and over with soil and about 5-6 inches above the plants. This was after a freeze and the plants were dormant. Last year and this year we have had about 2 ft. of snow cover. In the Spring get them uncovered early as Peonies start growth early. One year we left them just in pots on top of the ground and had very little snow cover and they all died.