We are looking into growing evergreen Magnolias as part of our nursery stock. Do you know what varieties will be the most cold hardy in the Pacific Northwest, and will be able to handle heavy snow the best?
You may have already come across this garden forum discussion on this very topic on GardenWeb.
Great Plant Picks suggests the variety ‘Edith Bogue:’
“The slow growth and controlled size of ‘Edith Bogue’ make it a good choice for courtyard and patio plantings, and its branches have strong resistance to breaking in wet winter snows.”
Their site also claims the variety ‘Victoria’ is resistant to damage from heavy snow.
This article from the Arnold Arboretum mentions Magnolia virginiana ‘Milton,’ also evergreen and supposedly resistant to breakage from snow loads because of its smaller leaves:
“The leaves are smaller in all dimensions than those of M. grandiflora, better suited to dealing with the snow loads that can be the death of the larger species, even for those cultivars that are otherwise quite hardy.”
I looked at several of our books on Magnolias, but snow load doesn’t appear to be a consideration for the authors–perhaps they’ve never walked around the Pacific Northwest after a snowstorm, and seen all the sorry-looking evergreen Magnolias bent and broken in the parking strip gardens! I suspect that even the snow-load damage-resistant varieties are susceptible to a degree. I’ve been observing the ones in my neighborhood. Those with a more upright, narrow structure seem to fare just a little bit better (gravity may make some of the snow fall off the foliage?) than the really wide-branching ones.