I haven't reached the upper end of zone 5 in 7 years from a temp perspective around here.

I tossed mine as the bronze color was too dirty looking for my liking. Minors of Milwaukee stopped growing them as they got too many complaints about the dirty winter bronzing. This was 5 years ago.

I wouldn't doubt if they can tolerate (not die) zone 4 extremes but will likely burn and suffer dieback

Green Splendor isn't supposed to bronze as much but may not be as hardy and drought tolerant.

My experience is some patience is needed. Mine looked a bit weather-beaten & bronzed the first few yrs in spring, but now show no cold effects. I'd reckon this is because the roots are now deep enough to stay below the frozen-soil line.

Sandy soil may help 'cause roots can grow quickly downward a long way in sand.

I wouldn't expect much bronzing in your area where temps typically don't drop below 0. The types of winter winds around here can be very dry coming on down north from Canada.

Where as you get warmer moist winds coming off the great lakes and/or the atlantic if I'm not mistaken.

Well, mine do not get too bronze. I do think they may be getting better in that regard, a la what Beng is saying about root growth. I mean, this story ain't over, but mine are in the coldest location I've yet heard about and are doing simply fantastic. Soil is a kind of mix of everything-sand, silt, clay, and lots of stones about the size of a large potato, for whatever the hell that's worth.

Anyone else.....GGs in Z4 or colder?

+oM

Hey Tom, where are they? No one in this area has really had a typical zone 5 winter in several years now for temp extremes.

Only reason I'm getting away with several plants in my garden.

Not sure if that applies for the zone 4 you're observing.

Whaas, we're talking near the little town of Suring, in central Oconto County, due east of the Menominee Indian Reservation. That's cold up there! You're right, "normal" may have to be redefined, but there's been some real cold stuff since these went in 4 years ago.

+oM

I'm sure you have one of the coldest potential locations, lol.

Its only one day but you had -20 for a low this year.

2012 was -6, couldn't get prior to that.

It may be a factor that in addition to temps, each of the winters since these went in has featured much snow. In some cases, a level 3-ft. on the ground was not exceptional in that area.

+oM