If you have room for 3 feet of plant width, butterfly bushes would be one choice. Lots of colors to choose from and the only maintenance will be to water and feed and cut them back hard in the spring. They even stay green through most of a mild winter. You can choose low growing ones like the Low and behold series or Adonis blue or tall ones ike Black knight or Royal red to suit yourself. Full size butterfly bushes can get wide, but they respond so well to pruning. No disease or pest problems.

If you need something narrower, you might consider clematis stans or even obedient plant, if you want low, or a hardy bamboo if you want tall. I only suggest bamboo if the pots are sitting on concrete since the roots can escape through a drain hole and you do not want bamboo in the ground. If you put obelisks in the pots, you could also go with any number of vines and go as high as the obelisk you choose--clematis, trumpet vine, perennial sweet pea would all work. Or throw some morning glory or moonflower vines in the pots every spring and go with annuals. The obelisks would provide winter interest.

The key is going to be what size and material you choose for the pots. In order to have the plants survive the winter you need a good size pot like 12 inches or larger. A resin pot will take less damage from freezing and thawing and will not dry out as fast as a clay pot inthe summer. If the pots are in unrelenting sun, the larger the pot, the less often you will need to water in the summer.

Kimka,

Thanks so much for your help. I'm planning on the pots being about 2 1/2 feet in diameter but the hieght can be any size. I have an 11 foot wide concrete slab backyard and want to place 3 potted plants in a row to go about 3/4 of the width of the yard. On either side is a 6 foot tall white vynl fence and I'd like the plants to be about that height, give or take a foot or so. The plants will basically act as a seperator to block the back of the area where I keep the trash cans and storage bin. I guess I need full, mainly vertical bushes. Blooming flowers would be a bonus but not a must have. The Butterfly Bushes sound appropriate but I'm not sure that they would like the 2 1/2 diamter pots. What do you think?

Thanks for the advice on the pots. I didnt know the size would affect watering frequency. Also, I probably would have bought clay plots instead of resin. Now I know better so thank you for saving me time and money.

2 1/2 feet diamter pots gives you a lot of choices. With full sun and no dirt underneath the pots, I think I would choose a bamboo. There are green, black, blue, and yellow stalked bamboo, so you have a wide pallette to select from. In a pot, they will not grow any near as tall as they will in the ground. As the bamboo fills the pots, they will create an effective screen. Butterfly bush may eat too much of your space, although you might give them a try as they will grow full and tall faster than the bamboo. If they prove to be too wide, you could always trade or buy different..

Think about grasses. Very hardy,so easily withstand winter in a pot, don't need a lot of watering once established, no dead heading or waiting for the bloom period to be attractive and good fall and winter interest. Buddlea won't look good in winter and they seed around - very weedy, actually categorized as invasive plant in this area, so good to avoid this one for the environment. I use mostly shrubs, grasses and perennials in pots for the patio and just a few temperennials - it's all very low maintenance and looks good!