I have zero idea about the particular cultivar you are asking about, however I do grow M. virginiana. Unless this cultivar is genetically modified (doubtful), I cannot imagine using M. virginiana as a screen. (Maybe if the imagination were addled with LSD M. virginiana could morph into a screening plant.)

I like my tree very much. The blooms are intoxicatingly sweet. It is one of the few Magnolias that likes wet ground. It fulfills all my needs, but the trees (I left a clump of 4) are 12 feet tall and it wouldn't take me 10 minutes to count all the leaves.

Also, you should note that in a cold winter, the leaves will brown and fall off. I've had a couple of years when April finds the tree with almost no leaves attached. It doesn't hurt the tree, but it blows the idea of using it as a screen out of the water.

I want to emphasize that this is for my species tree, not the cultivar you are asking about. The one you ask about would have to be radically different from the species to be able to use it for a screen.

The little bit i could find about 'Green Mile' says 'mostly evergreen'. Whether this is all the way up to zone 6, it doesn't say. It could be an 'australis' variety, in which case, it very well might remain mostly evergreen for you. Of course, even 'australis' loses nearly all leaves just prior to spring growth. My 'Mattie Mae Smith' does the same thing. It remains mostly evergreen all winter until around April when they drop. I'm in zone 7a.

In any case, with sun and adequate moisture, (and perhaps some pruning) I have seen Sweet Bay form a fairly dense upright tree - depending on cultivar.

I talked to someone at Bold Springs nursery in GA. He said that for 'evergreen' sweetbay magnolias, that they prefer the Green Mile to Henry Hicks. (I was actually looking for Henry Hicks when the Green Miles was given to me.) He said that Green Mile gives a very full tree, and usually only sheds a few leaves at the end of the winter. Time will tell if that assessment goes for me, up in Virginia. Until then, I am going to enjoy the flowers (there are 3 buds on my tree), and the beautiful foliage.

Here is a link that might be useful: Green Mile sweetbay

>stuckinthedirt, I wondered if you found the Green Mile sweetbay magnolia to keep most of leaves through the winter? Also, could anyone tell me if the Green MIle sweetbay magnolia or any other magnolias are tolerant of black walnut toxicity?

5 year old thread of course, so you may not hear anything back. Likewise the above link is stale. Unfortunately 'Green Mile' doesn't seem to be in the Magnolia Society International online cultivar checklist, that has historical and descriptive information for each variety included.

Green Mile is the tradename for Magnolia virginiana 'MVHH'. Rarefinds Nursery (located in NJ) lists it as "mostly evergreen".

Some sources list M. virginiana as juglone tolerant but others do not. It is sometimes difficult to get a consensus on what is affected by a black walnut and what is not :-)

Thanks for your response, all. I have found one source out of many which lists Sweetbay Magnoiia as juglone tolerant. https://www.jungseed.com/Gardeners/Articles/Plants-Resistant-to-Walnut-Toxicity#.