North American Fruit Explorers mailing list at ibiblio

[Alan Haigh <alandhaigh@gmail.com>]

I've never had a problem with a site that has a whole foot of soil before
ledge- hell, I've worked with much less than that in the hills I ply my
trade in.

I don't happen to use the Cornell roots very much, but I assume 41 is full
dwarf so it really doesn't need a lot to work with.

Where shallow soil can be an issue is with cold sensitive rootstocks, and I
believe, even with trees susceptible to cambium burn, such as Santa Rosa
plums and most of the red-fleshed J. plums. My cots seem even more likely
to die when grown in shallow soil.

Obviously, you haven't much a reservoir to work with so an organic mulch
would help as would irrigation during dry periods.  This is especially the
case if there are nearby big forest trees.  Their ability to suck up water
extends not just beyond their limbs, but even beyond the roots due to
mychorizal symbiosis.