The StarTribune had an article about it last month. They talked to someone at one of the local nurseries who said they'd been experimenting with a patch of zone 5 plants, but urged caution to people about spending big bucks on less cold hardy plants.

Meanwhile, I've been planting a zone 5 plant here and there in the yard over the past ten years and they are all doing great. I'm at the point were I'm thinking of trying a Japanese maple or a nectarine tree next.

Though, if the current cold snap gets below -20F I may change my mind.

Puts me solidly in zone 4, tho so I am not complaining! I used to be on the border between 3 & 4.

Linda

There is a lot of talk about zone changes all over the country, but I think these zone maps have limited use for one important reason. They only refer to the coldest temperature recorded during a winter--not the duration or frequency of cold weather. Which is worse for a marginally hardy plant: one brief exposure to -22 F with no wind during an otherwise mild winter, or a few weeks of windy brutally cold weather with the temperature dropping to -15 at night and staying below zero during many days? The former would be a zone 4 winter (lowest = -22). The ladder would be a zone 5 winter (lowest = -15). But I am willig to bet that more tender plants would die during that "zone 5" winter in the example above. The new map shows my location as zone 7, the same as northern Mississippi. But I don't buy it, for the same reasons I described in the above example. We almost never drop below zero in my area, but we do, of course, have much longer and more intense cold waves compared to northern Mississippi!. It would be great if someone could develop a new map which combines the lowest temperature typically reached in a particular area with duration and frequency of cold. It would be a much more useful zone map to predict plant hardiness.

It's not official, though it depends a bit on how you want to define official. The USDA which determines the zones has not changed ours:

Here is a link that might be useful: Read about it here

Mine hasn't changed and though I'd love to be able to use zone 5 plants here, I won't be going out and spending big bucks on any to try.The current weather here-10 to -24 for the past week every night along with wind pretty much tells me I better stick with zone 4 plants.

I'm surprised to be so solidly in zone 4, but I really don't trust these newer zonings, especially with these cold temps and not much snow cover. I fear what I might find this spring.....or, rather, not find!