A white mandevilla might work.

Kate

Thank you Kate. I did a google image search and this is truly a wonderful plant--exactly what I asked for. I would, however, like something that will be a perenial in the Twin Cities. I understand there are new hardy cultivars but I don't know of any zone 4 ones. If there are, please let me know where I can get them. Thanks again!

It might be a bit of a challenge keeping a perennial alive over the winter in a container. Can you tell us more about its size and siting?

Hi leaveswave,
I haven't had any problem keeping stonecrop, hostas and daylillies alive in containers--even after last winters cold with no snow. I did lose a couple of plants that were planted in my yard however.

The pergola is about 9 feet tall and 10 feet wide. Very little depth. I'll attach a pic in the next few days. The containers I am planting in are pretty large. I am not sure exactly but about the size of a half wine barrel, maybe a little smaller. The deck is on the West side of the house so it gets pretty good sun most of the day.

There might be a white clematis that repeat blooms. Many annuals do tend to have longer bloom times though, so depending on how important that is to you, you might want to consider them. I also googled the white mandevilla and it's very attractive, isn't it?

I don't know how it would grow in a container, but I had a Sweet Autumn Clematis that would bloom in profusion with tiny white flowers from late August until frost. It smelled devine and grew like crazy! I planted other clematis along with it, so that I would have early blooms as well as the fall blooms.

I am attaching a link and the photo isn't an exaggeration.

Here is a link that might be useful: white clematis

Here's a pic of the front of my house. The deck is not finished yet so be nice! It will give you an idea of the pergola though.

The sweet autumn clematis looks like it will work great for fall blooms. What gorgeous flower clusters. Thanks hollandgirlt! I'll use an early blooming clematis for the summer and I should be set. Thank you all for your suggestions.

{{gwi:1052953}}

Wow- Nice pergolaaahhh! It looks great- just like that space has been waiting for it all along! I am sure you will enjoy it for years to come!
I really enjoy my Clematis Miss Bateman- which is a rebloomer and grows on old wood (wont need as much pruning as Sweet Autumn) which has huge early blooms with sporatic flushs of smaller blooms throughout the summer which might be one for you to consider that might work well for your plans-
Great job!
Julie

Thank you Julie. It's funny you should bring up Miss Bateman clematis. I planted one three years ago and the first couple of years it did little. This year however, it was covered in the most beautiful white blossoms. Unfortunately, I had to move it to add on to the deck. I suppose it will take another three years to settle into it new home again. Thanks for your post. You picked my choice for white clematis right on the nose.

I found my white mandevilla to be a very slow grower and less than desirable bloomer and it is not hardy here, but maybe it had a wee bit too much shade.
jan

My Blue Angel clematis is in a pretty shady location and has been slow to fill in, so the last two years I've planted an Asanaria vine on either side. What a fabulous combination! I know you said you wanted to avoid annuals, but it'll give you a contrasting flower shape and color while your clematis fills in. Even though my clematis finally took off this year, I think I'll continue to plant the asanaria because the combo is so great.

Fitz

Darn it, spelled it wrong again. Good thing I checked after I posted, although you'd think I'd learn to check before. It's ASARINA.

Here is a link that might be useful: Asarina Joan Lorraine