Marie Forte is a hybrid involving r. catawbiense so it ought to be hardy to -10 to -15 at least.

I do use burlap screens for wind protection for plants going into their first winter or ones located in particularly wind prone locations. I also use Wilt-Pruf. You will find many studies which seem to indicate this product does not work, but many years of practical experience - my own and others' - has convinced me the small investment in money and time is well worth it.

Marie Forte is an old Waterer hybrid from 1880. It is known to be hardy to -15F. So using burlap screens in winter could help. Here is a photo of Marie Forte:

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The red Nova Zembla is much hardier and a good plant. Here is Nova Zembla:

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