Never heard of either one being sold as a "grafted shrub tree." Not even sure what that is! I have several 'Diablo' ninebarks and they're enormous shrubs that send up new stems regularly. I can't imagine why or how they could be grafted onto anything.

You also might want to check to see if burning bush is invasive near you. It is around here, escaping into the woods and wild areas. I also don't think of it as a good screen, and it's not a particularly attractive shrub most of the year - just green and twiggy, only turning pinky-red in the fall. Diablo is a dark red to greenish-red, depending on time of year and amount of sun. It also has flowers and attractively shaped leaves. To my mind, a much nicer plant. Also, check out 'Coppertina' ninebark.

For screening, the shrub form would be more useful. In general, grafted standards, which have a trunk with a shrubby or weeping plant grafted on top, are intended as single specimens. They usually need more attention with pruning of sprouts from the lower portion and for shaping of the upper portion. I also can't see why anyone would want to graft either of these plants, and would check out your source on the Garden Watchdog to see if they are really a reliable company. They have feedback from many, many gardeners on different companies.

A final thought - my preference is for a mixed hedge of several different varieties so that there is a variety of foliage texture and color, bloom time, and bird habitat. I have a long hedge I put in last year for screening with three kinds of evergreen, some small dogwoods, hydrangeas, deciduous hollies, and rhododendrons as well as a few vines and large herbaceous plants. It has several plants of most of the varieties and has been decorative all year (except when it was completely covered by snow for several months this winter.) ;>)

Here is a link that might be useful: The Garden Watchdog

The tree forms are trained, not grafted (at least at the company I work for).

I have heard Diabolo sends up a lot of shoots, trying to revert back to a shrub.

Depending on the layout/design of the garden, using the tree forms would allow you to underplant with annuals/perennials if you wanted.

Wow! Thank you all so much for answering my questions!
Nhbabs, after I left my original post, I stumbled across the copertina ninebark and fell in love with it! I really want one. I have clay soil though and I'll have to look into the specifics. I have a small backyard, so one shrub or tree that can serve as a screen and/or specimen is what I'm looking for. After that I can build off of it, and slowly add new things. I agree about the burning bush being overall too large and "boring". Thank you for the link, I'm going to check it out.

Clay shouldn't be a problem for any of the ninebarks. They're tough shrubs that are highly adaptable to many difficult situations.

Hi laceyvail,
I'm thrilled about being able to grow the copertina ninebark. Can you please tell me how old yours are and how high? I'm just trying to get an idea of what "medium growth" means.
Thank you for your time!

My Coppertina is two years old, I think, and is about 5-6 ft tall and about as wide. I think Diablo grew faster, but not sure. I also put in a Lady in Red (from Klehm's) last fall, so it's still quite small, and I'm not sure yet how it will differ from the other two or the Summer Wine, which I also have.

Any of the ninebarks would be good candidates for screening (if you don't need anything over 8-10 feet) but so would a number of other large shrubs, including some viburnums (V. sargentii 'Susquehanna'--12-15 feet--for example), Kolkwitzia, Buddleia alternifolia (a non-cutback buddliea), and many Magnolias (a few are hardy into zone 4). I would definitely plant a mixed border--too many purple leafed shrubs in a row would be heavy and boring. use a few conifers too.