Anything rated Zone 3/4/5 (if you have Zone 6/7 winter) should do okay in a container, provided there is adequate drainage in the container and you can take steps to do some protection in severe cold spells and keep excessive moisture out of the container through winter, which can often kill a plant faster (rotting a crown) than any cold. The phloxes (paniculata/"Summer phlox" or subulata "creeping phlox") are hardy to Zone 4 & 3 respectively The heucheras (depending on type) are hardy to Zones 3/4 Astilbes are generally Zone 4. Daylilies can be Zone 3/4 depending on variety. Many of the mints (a large family) are very hardy and many of the menthas within that family are generally hardy to Zone 3. They can also grow in shade where other herbs prefer more sun. Some of the other plants you mention like the vinca, impatiens, trailing lobelia, pansies, basil are either tender perennials or annuals and may or may not reseed. I have seen the regular impatiens reseed here but not sure about the new guineas. One good reseeder as annual or perennial depending on variety (where some are hardy and others tender) are the salvias (which are in the mint family). They do like a little more light but some of the dwarf varieties might offer a nice combination plus with dead-heading, they can go from all summer until frost knocks them back. Another mint family potential reseeder and/or perennial are the balms (lemon balm, bee balm, etc). Yet another possibility includes one of my staples - the wax begonia and petunias. I have had both reseed as well and with the begonia being a tender perennial, they can be scooped out and nursed inside to be planted out the following season. They like other tender perennials, tend to have a longer bloom duration than the hardies - akin to annuals. The petunias bloom better in more sun but can have a decent bloom in part sun. Don't be afraid to grow perennials. If they spread, just dump them out, divide, and replant! I've done this with my containered daylilies and hostas and will be doing it for my asiatic lilies hopefully this fall (I keep putting it off...lol).

The primary problem is freezing. The water will freeze and in and of itself this isn't a problem. It's like a perennial in any other container. Where the problem comes in is the water freezing and expanding against frigid cold plastic and breaking it. I make extensive use of self watering containers, but only for annuals. If I were to try to overwinter a perennial in one I wouldn't fill the reservoir at all, I would simply top water the mix directly and in the winter only if the mix was bone dry. I would try to avoid a completely full reservoir that would just become a big ice cube.

The suggestions below were provided by the folks in the perennial forum. Posted by pegnj 6nj What are some of your favorite perennials for winter interest? I have a 9' paver circle in front of my front door/landing. FULL SUN. It is surrounded with some small trees and some backbone evergreens/shrubs. I put in some perennials (baptisia, peonies, salvia, catmint)and annuals but now that everything is starting to die back I realize that any other perennials I add should add something in the winter. Until the bushes get bigger I don't want so much bare mulch by my front door. The santolina still looks great and I am planning on adding some grasses and maybe lavender. Which are the nicest grasses to mix in with perennials and that won't get to big? Does artemisia hold up nicely for most of the winter? does it behave around other perennials? What are some perennials that even if they "die back" still look interesting and not just dead? -------------------------------------------------------------------------------- Posted by: gardenbug Canada zone 5 Grow something fun on a pretty medium sized obelisk...and then the pretty obelisk will entertain you in winter. Small clematis for example. I also love grasses, but many blow over in the wind. Hameln is sweet. See here: I find most plants simply look dead. Some people like the look of sedum seedheads in winter. I like anything that attracts birds. A well stocked birdfeeder (not a birdhouse) is the ultimate winter interest for us. Shrubs with berries provide interest too. -------------------------------------------------------------------------------- Posted by: chervil2 z5 MA Sage looks like sage all year round and it is useful next to the door so that you can easily grab a leaf for your cooking. Thymes and winter savory look alright during the winter as well. My Johnny Jump ups often flower during the winter months. These plants reseed easily. Once you have a Johnny Jump up you have them forever. Cheers! -------------------------------------------------------------------------------- Posted by: mgrace z4MIUP Rugosa roses that form hips are also interesting. I also enjoy the birds and any shrubs which have berries to attract them. I love my Karl Forester ornamental grasses right now. Also I have alot of astilbe in a partially shaded bed. I leave the flower heads and they turn a deep russet shade. Soon, though, we will get a thick blanket of snow and it covers everything. I'm going to be adding some more conifers for winter interest. -------------------------------------------------------------------------------- Posted by: Tracey_NJ6 (I love sedum and don't cut them back until the spring. But for great looking foliage, try Arum italicum. The foliage dies back in the summer just as the berries appear, which to me, aren't worth it. After the berries die, the foliage reappears, remains until the next summer and is lush and green all winter. This photo is a bit blurry, but you'll get the idea. -------------------------------------------------------------------------------- Posted by: BeigestoneHill z 6 /7VA I love the different Acorus in the winter, beautiful texture and pleasing green and white and chartreuse colors. I too love Sedum Autum Joy in the winter. My favorite grass in the winter is Miscanthus 'Adagio' it never falls over and looks great until early spring. -------------------------------------------------------------------------------- Posted by: jwillis01 7a ) I second the Arum italicum suggestion, I also enjoy our Rohdea japonica during the winter months. Mature clumps hold bright red berries during winter that contrast the dark green leaves very well. I also like the low-growing silvery foliage of Dianthus gratianopolitanus. I have grown several cultivars, but I still prefer 'Bath's Pink' best of all. -------------------------------------------------------------------------------- Posted by: Franeli z4 NH Here in Z4 I have an edge planting of Veronica blue'. Even with the temperatures as low as 9F and several snow days, this plant still has beautiful burgundy foliage and looks great in front of some dwarf pine shrubs. I wonder how those Veronica's would look in winter with blue fescue grass.(?) I also have Veronica Incana: silver-gray ground hugging foliage that looks great next to creeping and lemon thymes. -------------------------------------------------------------------------------- Posted by: floresbellas z5 MI Iberis sempervirens, heuchera, armeria, blue fescue, creeping thyme. -------------------------------------------------------------------------------- Posted by: sbeuerlein zone 6 Has nobody mentioned hellebores? Awesome winter interest, great foliage, even flowers. Speaking of flowers, how about Erica carnea. Flowers from now until March. A few of the sedums are evergreen. Scott -------------------------------------------------------------------------------- Posted by: oldroser z5 Arum italicum pictum is hardy up here so definitely not a zone 7 plant. Mine is just starting to grow (which it does every year around this time and continues through the winter) but is not as lush as the picture, maybe because it is in shade? Or poor soil? Or both?? -------------------------------------------------------------------------------- Posted by: gardengal48 PNW zone 8 Anything that remains evergreen through the winter months I consider a candidate for winter interest. That includes euphorbias, heucheras and their cousins, hellebores, evergreen ornamental grasses (carex, fescue, blue oat grass, liriope, mondo grass, phormiums), ferns, perennial herbs like salvia, lavender, rosemary; many of the alpines or rockery plants like helianthemums, iberis, armeria, stonecrops, arenaria, dianthus; groundcovers such as lamium, vinca, kinnikinnick and epimediums. Plus, some plants just look their best at this time of year - Iris foetidissima has produced deep orange seedheads, Schizostylis (now called Hesperantha) is in full, late season bloom, many hardy hebes will bloom now right through winter in a sheltered location, earlier species hellebores are setting buds, bergenias have changed to their burgundy winter color and a number of evergreen groundcovers like wintergreen, veronicas and rubus have developed their burnished winter color also. -------------------------------------------------------------------------------- Posted by: SallyM z4 MN You mentioned you have trees and shrubs in your front garden. Do any of them have red foilage or red twigs (IE: red twigged dogwood). Also, trees like the river birch have great bark throughout the year. Depending on your tastes, how about something like rattlesnake master (eryngium yuccifolium). My artemesia does not even make it throught the summer without getting ratty. I have to cut it back for new growth. I second gardenbugs suggestion of Hameln. Sally -------------------------------------------------------------------------------- Posted by: Monique 6a CT At the Brooklyn Botanic Garden last March, the Yucca plants were looking pretty good. I just bought one this year, so I don't have any winter experience with it yet. The rest of my winter interest perennials have all been mentioned. I love red and yellow twig dogwoods and there are some dwarf cultivars out there. -------------------------------------------------------------------------------- Posted by: Tracey_NJ6 No, I'm in Bergen County, close to the George Washington Bridge, zone 6. My Arum italicum has been doing wonderfully; I've had it since 1997, purchased from the dreaded Michigan Bulb Co. It was bareroot and remained small for the first few years. It didn't even produce the berries until 2000. It's grown wonderfully; I only keep it for it's foliage; the berries aren't even worth the show. Thankfully they're short and will be hidden by new plantings. I just decided to turn that bed into a hummingbird area, since I finally had my very first 2 visitors this summer.

I have a wooden whiskey barrel and a clay chimney tile, both of which have ribbon grass (a plant too invasive to allow to roam the garden IMO) that has survived many years. I wasn't able to overwinter bulbs, hosta, or chrysanthemums, among other plants I tried, despite the planters being buried in snow for the majority of the winter. If you want to have your zone show up with your name in the posts: Go to Your Houzz in upper right of every page, click Edit Profile, and on the left side click advanced settings. Well down the advanced settings page is a blank labeled Climate Zone for Garden Forums along with a link to find your zone. If you add info on your state or the nearest large city you will get even better information since zone only relates to average coldest winter temperatures. Then return to the top of the page and click Done Editing.