Considering where arctic willow grows naturally, I'm suprised you've kept it alive as long as you have in your summer heat! It naturally grows as a tiny little "tree" in the arctic and subarctic tundra, according to what I just read - I had to look it up.
I've got two black willows, one I just planted in my garden and one still in the pot, and as long as they get plenty of water, they're fine. Black willow naturally grows in areas of constant or near constant water, so that's it's thing.
I don't know of any willows that are drought proof - as far as I know, they're all water lovers.
If I were you, I'd just pick a native willow and don't let it dry out.
Sherry

Christie,
My arctic/alpine willows did fine and were quite hardy. I had them in skrees with Picea pungens, Populus tremuloides and other alpine plants back when I lived in Zone 5. They liked moist soil even though they can survive droughts. But they didn't like the combination of high heat and high humity, so they suffered a little in the hottest part of summer when it rained for a few days. Mine were transplants from above 10,000' brought down to 4200'. They have a massive root system BTW. Anyway, they were still going strong when I sold the house after 9 years and moved to the desert. Don't know how long they live off the top of my head.
Larry

I have a Black Willow (Salix nigra) in about a 15 gallon pot, that I intend to pot up to a 25 gallon next year. So far, it has done well. I did forget to water it at one time in early summer and it dropped all of its leaves. I thought it was a gonner. I scratched the stem to see if the cambium layer was still okay, and it appeared to be. I resumed watering it, trimmed off the dead portion of the stems, and it grew back just fine.

Willow is extremely easy to root. If you can find some close by, you can cut a few 3' stems, and stick them in some dirt, watering them daily, you will probably have roots in no time. Willow contains a chemical that promotes rooting and is often used as a "rooting" agent when attempting to root difficult plants. So, it has an unabashed desire to perpetuate.

For me, I only grow the one because these trees are dioecious. I don't want to end up with a male and a female that produce seeds. I don't have enough room. Willows are also know for their need for water because it is not recommended that they be planted near sewer and/or water lines. The roots will more than likely seek out these lines, get into them, and can cause a lot of headaches and damage.

I think the Blue Arctic Willow is supposed to be hardy thru zone 7, but it still may be too hot in Missouri to grow them well, or for any length of time. Probably would do fine in the Northwest's zone 7 - very different from Missouri, though. I know I wouldn't attempt it in my zone 7a because we just get too hot on a consistent basis.

Good luck!

Susan

Christie, I had a regular pussy willow and it just lived several years and then died. I am told they are not extremely long-lived trees. I would love to have a large willow tree hanging over the bank of the pond but have never got around to planting one.

Thanks for your replies everyone. It would be much easier to find room for a shrub rather than a tree. I thought my Blue Arctic Willow would stay small. It was supposed to be a dwarf but is about 8 feet by 8 feet.
I'm still not sure what to get. I've seen a few articles that say "especially black willow" as a host plant but it would be nice to have something smaller so I can find the cats. That's part of the fun. : )

Glenda - I love the look of weeping willows and have thought about just plopping one out in the middle of our hayfield. I wouldn't put one in the yard. It would be nice to have one in a field or by a pond like you said where you wouldn't have to trim the branches up and they could hang all the way down to the ground.

Sherry and Susan (or anyone else that has Black Willow trees) - Have you found any cats on your willows? I think I like the idea of growing it in a big container on my patio, then when it starts getting too big, I can just take cuttings again. I have some large cattle supplement containers that would support them for quite awhile. Do you think I've waited too late in the year to start some cuttings?
Is there any chance that I could beg a few cuttings from someone? I'd gladly send seeds or plants in trade.

Yes, Christie, I found red-spotted purple cats on my black willow earlier this year. Willow roots very quickly, so you should have plenty of warm weather left to use for rooting them outside. I'm sure black willow grows in your area, just look around ponds, lakes, creeks and rivers where it stays wet most of the time.
I plan to keep the one in my garden wet and pruned, so that it makes new growth pretty much the entire growing season, even if I have to fertilize it, which I doubt I'll have to do.
I think your big containers would hold black willow for several years, but eventually you'll probably have to plant them.
Sherry