Cedrus deodara 'Eisregen' No winter damage to -17° !

The Cedrus deodara 'Eisregen' survived -17° with no winter burn at all. It is somewhat sheltered from sweeping winds by a pair of mature hemlocks on it's north side and small storage buildings on it's east (neighbors shed) and west sides ( my shed.) It's about 15' tall. I really did expect it to have some needle burn, at the least, but there is none.

One I saw in Denmark (zone 7) survived -27° in a severe winter, which killed off all the normal Deodar Cedars.

Resin

That's amazing! I've been uncertain about reporting the hardiness of this particular cultivar because of the wind protection it receives here. Perhaps I needn't be so hesitant. I think this cultivar has a good future here in the colder regions where other C. deodaras fail. It's widely reported to be grown from seed collected by Karl Fuchs from the cold, mountainous Pakati region of Afghanistan. Just how cold that really is I don't know.
If the seed was collected from the higher elevations it could have been very, very cold. How dedicated a plantsman you must be to collect seed from a mountainous region half way round the world.

Yep, not to mention in an area that while then not quite as lawless as now, has always been a dangerous area to go to (would like to go there myself, but wouldn't have the courage!).

I'd still be a bit cautious about zone 5 however - if it can get down to -27 in a really severe winter in zone 7, you can expect it to get down to well below -30, perhaps even -35, in zone 5 in a really severe winter. And I doubt it would survive that.

Resin

I'm told by other DGr's that this past winter some areas of zone 5 (Iowa is one I recall) did experience record lows close to what you're talking about. Your caution is well founded.

It is also worth noting that you are both speaking of roughly the same temperature.

Since neither of you has designated it, I would guess Snapple is speaking in terms of °F (being in the USA) and Resin is speaking in terms of °C (being in the UK).

Minus 17°F converted to °C, is minus 27.22°C. So you're both speaking of roughly the same temperature. It's important to designate which scale you're referring to when posting temperatures since folks from all over the world use these forums.

For anyone that needs a temperature converter, one can be found here: http://www.temperatureworld.com/tempcon.htm

Just an update on the 'Eisregan'. It's had a beautiful growing season and looks as though it's close to reaching its maximum height. The terminal leader has halted and four evenly spaced long shoots are now the top. It's about 19' as near as I can judge. I'll get a shot soon and post. I would encourage anyone intersted in a Cedrus deodara to give this one a try. While I can't say what happnes if it's in a cold exposed windy site I can say that it tolerates 97°, high humidity with gusty winds. So far nothing has fazed this tree in zone 5 with moderate winter protection.