You need to head in the other direction :-) You want perennials that are hardy to at least zone 5. However, that advice can be taken with a grain of salt. A lot depends on container size as well. Larger containers tend not experience the temperature extremes as much as smaller containers - harder to freeze a larger soil mass. And clustering containers together over winter can create a microclimate that allows for greater cold tolerance.

I am in a warmer climate than you, so keep that in mind, but all of my containerized plants remain outdoors throughout winter without any significant protection. In some cases these include plants of marginal hardiness for my area. With most of these, it is the improved drainage provided by a container situation that makes the difference, as they would normally languish and possibly rot out in our damp winter soils.

It is unusual for our zone 8 to experience frozen soils for any length of time deeper than an inch or two. But I would avoid smaller containers to test your plants' hardiness, as smaller containers (1-2 gallons) have a much greater ability to freeze solid, especially in a colder zone. Nearly all of my containers are a minimum of 16"x16", whatever that translates to in gallons, most quite a bit larger.

And FWIW, my nursery is borderline zone 7/8 and all our outdoor plants remain outdoors through winter, with very few exceptions (primarily those that prefer drier conditions). These include even smaller 3.5" groundcover plants, 1 and 2 gallon perennials and all trees and shrubs. We lose very few to winter cold.

OOops! It would help if I counted in the right direction. Thanks for checking me back in gardengal, and thanks for the advice too.

I generally look for perennials hardy to zone 5 so I won't have to worry about the winter.
I have some non-hardy ones that I over-winter in my mother's basement. (Canna, Tuberose, callas, elephant ears & Dahlias)

I don't have enough light or space to take in a lot of plants so I have lots of hardy perennials & annuals.
The day lilies came with the house (I've been here 10 years) After dividing them - sharing with family, I now have 4 pots. They come back faithfully every spring and bloom throught the summer- even surviving attacks by a local raccoon who thinks they are tasty. :oD

Other Stay-Outsiders: Phlox, Yarrow, mint, chives, coral bells. Bee Balm, dwarf Lilac, hops, honeysuckle, gay feather, black eyed susans, strawberries & blue berries.
Most of these I have had for over 7 years.

Here's my yard in mid-August-
{{gwi:48746}}

Here is a link that might be useful: More garden shots (and other stuff)

I am in zone 6b. I have a Japanese maple in a container. What would it require to winter in the pot?

Best would be to bury the container to the soil line against the north side of a heated building away from sun and winter winds and mulch well. Some protection like a burlap wrap would help to guard the top against dessication if the site is windy.

Not so preferred, because the tree is guaranteed to leaf out too early in spring, is to overwinter in an unheated garage. If that happens you'll have to do the "Acer two-step" (move the tree in and outdoors as temperatures allow) until danger of frost has passed to prevent the long internodes and weak growth that will occur in the garage and destroy the trees form by radically altering its normal growth habit.

Al

You could try too group them together and fill the gaps with mulch for more protection as well.

Most of my Stargazer Lilies did not survive overwintering in pots and none of them rebloomed the following year, but it may not necessary be an issue of temperature protection but water and pot size. The problem can also be because I'm just starting to and still learning about caring and overwintering bulbs and didn't get the best or proper instructions, or that most bulbs unless specified will not bloom in containers the second year. I'm still searching.

... or an issue of insufficient sunlight or too much during dormancy. Does anyone have steps in overwintering potted lilies (or containerized Stargazer) year after year? Any input appreciated.

I have a unheated garage/barn. The downstairs averages about ten degrees warmer than the outside in winter. The upstairs can get much warmer. If its in the 30s and sunny the upstairs can be 50. Which is better for overwintering? Up or down. filix

For overwintering material hardy to zone 7 & below, down is better by far. For 8 - you might be able to get most material through the winter upstairs - that part is hard to guess at.

I hope George is OK with your piggy-backing on his thread, Filix?

Al

Thankyou Al. And yes your right about piggy-backing. Should have asked first. Sorry George. Hope you don't mind. filix