Hi Plant Love, I'm no tree expert (Treebarb??) but I imagine that if the tree is well established, it should do fine. If trees died at early frosts, there would be none left in Colorado.

that being said, three yeats ago there was a VERY hard freeze after a prolonged warm spell in November, and tons of trees and bushes died, including our mature juniper hedge that blocked our neighbor's view of our house. But I don't think that 25 degrees would do that...thoughts, anyone else?

Thanks for the response. What types of trees died during that very hard freeze? I know that certain species are much more suceptible. I have a crabapple that can take 20 freezes and still have nice fall color and no burn.

I agree with Faith. I would venture to argue that the majority of trees that have matured along the Rockies are probably hardy enough to withstand all but the most brutal seasonal changes. Dramatic swings are not at all unusual, particularly in fall and spring. Freak incidents like what happened back in November 2014 are mercifully rare, but incredibly damaging. We lost both of our gorgeous Newport Plums - the bark just split right open like they were struck by lightning - and had significant damage to our 5 Arborvitae, but they are extremely hardy and survived. My lilac also survived unscathed. Most other evergreen trees (spruces, pines, etc.) weathered well since they are generally very cold tolerant. Most of the damage I saw in my area was to broadleaf trees (lots of Aspens) and juniper/arborvitae. Many still haven't been replaced because the damage was so widespread.

To give you an idea of what happened in November 2014, we had highs mostly in the 60s and 70s for the first 10 days of the month; on top of being 4.2F above normal for the month of October. Many trees still had leaves because of the unseasonable warmth. On November 10, the high temperature was 64F, but a strong front moved through and we dropped to 13F before midnight. On November 11, we registered a high temperature of only 16F. What really did the damage were the low temperatures of -13F and -14F on the mornings of the 12th and 13th, respectively, in addition to lows between -1F and 5F through the 17th. The rest of the month rebounded to primarily above-average with highs in the 50s, 60s and 70s. The temperature swing for the month was a remarkable 86F (highest temp 72F, lowest temp -14F).

I hope it doesn't happen again anytime soon. Like I said, it's pretty rare to have such intense temp swings in such short periods of time, even for this area. Most plants have mechanisms in place to survive, but even they can be susceptible under extraordinary circumstances. I understand it's best to plant perennials that are rated for at least one, preferably two, zones colder than your immediate area (e.g. plant zone 3 perennials in zone 5, plant zone 2 perennials in zone 4, etc.). This helps to ensure you have plants that can better withstand abnormal cold snaps. Of course, timing plays a huge role and there isn't much one can do when temps go from 60s to -10s in 36 hours. Hoping and praying go a long way! :)