I'd go with a fallback. If you truly desire blue ash, Outback Nursery is probably your best choice, or mail order form out of state (Forestfarm).

There are a great many Ash trees, and I consider the true test of an ash to be...how does it look many decades later. A large number of the green ash varieties, even in the nursery, they look just like another. My personal favorite ash trees are Prairie Dome and Prairie Spire, both green ash varieties, Mancana Ash, a Canadian selection of Manchurian ash, and Fallgold, a Canadian selection of black ash. After those four, then come the white ash, such as Autumn Purple. I'm going to be truly radical and include Cimmarron (sp?) with the white ash, because of the fall color...not enough reason otherwise to differentiate it from too many other varieties of green ash.

As for the blue ash, part of the reason it's hard to find is that propagation is moderately difficult, and there are too many other trees closely related, looking much the same, serving the same purpose in the landscape. As much as a nursery may try to offer a full complement of plants, there are simply too many and they rightly have to make decisions about what is going to take up space.

Kudos on your quest to be different.

Although there are native white ash in Minnesota, to my knowledge no one sells it, except maybe Outback in Hastings. Outback grows from local, native seed stock whenever possible. Autumn Purple hails from out east and has not proven reliable in the Twin Cities area.

Rick

Thanks to both of your responses. I emailed Deborah Brown at UMN with the same questions and she was nice enough to respond as well. She agreed with you Rick about the reliability issues with Autumn Purple here in the twin cities. I visited the Landscape Arboretum yesterday and they have two spectacular autumn purples in good shape so it can be done. I am thinking to nix both the Blue ash and autumn purple at this point.
Heptacodium, researched your suggestions and I really like the look of the Fallgold Black Ash. Do you have one laying around I can visit? Thanks for the input.
Excelsiorgolfer

Excelsiorgolfer - you have gotten some excellent advice both here on the gardenweb as well as Deb Brown. Autumn Purple is really a beautiful tree, and in protected areas it can be done. Hopefully you have a protected area in your yard, or microclimate where you feel you can place this tree without losing it. Location is the key. have fun!
PP

The white ash cultivars provide some of the best and most reliable fall color in the twin cities landscape. They are about at their peak now. I would highly reccomend using them. Attractive and relatively mature specimens can be seen on the St. Paul and Minneapolis campuses of the University of Minnesota. They are also being used as street trees in St.Paul. I agree with Leftwood that there are some winter injury issues. On the south side of young trees bark splits can develop over the course of the winter. This can be avoided by wrapping the trunk...tree wrap, burlap etc...or by siting it so that the winter sun does not hit the south side. Do not let this issue keep you from planting one. The real issue with at least one of the white ash cultivars may be virus spread by way of grafting...Salicaceae can tell you more about this. Blue ash are also really great trees..it's interesting you were impressed with the Arboretum specimens..some of them look so much like green ash. The nicest specimen of blue ash is on the UW River Fall's campus it looks very different from the Arboretum trees. Its bark is much smoother and it is cream in color-very, very attractive.

Well here I go. I guess disregard my previous message! I visited the Nicollet Island brownsite http://www.cnr.umn.edu/FR/extension/brownfield2.html
where there are multiple plantings of different shade/street trees planted in an area where the soil was dramatically altered. It is basically a study by the U of M to see which trees survive tough soil conditions(subdivisions, etc.). The trees were all planted in 2000 and are tagged. I recommend to take a look for anyone going through the same process as I am(I can never make up my mind). In any case, all the autumn purple there look great and the studies show they have adapted well to the site so I made the plunge and bought one at Gertens and will have it planted tomorrow. The people at Gertens do recommend wrapping the tree during the winter months for about the next 5 years just like you mentioned John U. to protect from splitting. I will let you know how it turns out for me. As for the Blue Ash, I will have to visit it sometime at River Falls. What attracted me at the Minnesota Arboretum to the Blue Ash was its form, branching and the leaves had this amazing gentle dark green-blue hint to them. Just a beautiful tree. I have room in my back I may get a mail-order smaller tree and give it a try.
I have to say I have been so impressed with the level of knowledge on this Minn forum as well as the general forums. You know your stuff!
Thanks for all your insite and help.
Excelsiorgolfer

FYI, a while back I spotted what looked like a nice mature Blue Ash planted at the U here in the Cities, maybe at the entry to Carlson, I can't recall totally. Kind of sheltered. Very special.

There are also some young..but good looking blue ash on the U's St.Paul campus. There are a lot of nice plant materials there...Corylus colurna, Redbuds, Pinus rigida, Abies lasiocarpa, Pinus koreana, Acer triflorum, Acer nikoensexgriseum, Taxodium distichum, Cladrastis lutea, Magnolias-many..including tripetala..Acer tegmentosum,truncatum, barbinerve, hickories, chestnuts on and on.