I knew it! I am now 8a.

Looks like I'm now zone 6. Eh, doesn't really make a much of a difference for me, its the microclimate that does.

Looks mine is downgraded to 7b

edit: by looking into state details, my area is still 8.

About right for me. We were 5A 50 years ago and 6B/7A now.

As the climate warms, I wonder if we'll see a new sort of hardiness classification with respect to maximum temperatures that a given plan can withstand.

Actually Karin, I'm seeing things (over my lifetime) that have definitely shifted, like the longer time temps are typically too high for tomatos to successfully develop fruits. Same with flowers, snapdragons for instance are mostly relegated to spring time displays now...similar to pansies.

I can’t tell the color difference of the green for zone 6-7s. I’m in northeastern NJ right below nyc, is that zone 7b or still 7a?

@Heruga (7a NJ) You can find a much higher resolution map and the ability to search by zip code on the actual USDA site here:

https://planthardiness.ars.usda.gov/

Thanks, I leanred that I am in 7b now. Wonder how many more years until zone 8 and whether my cool climate plants will still be alive 50 years from now due to the heat factor, if NJ isn’t underwater by then. I adore my Japanese larches and spruce(picea koyamae) which grow in cool summer regions and I hate to see them die after growing so big all the years.

I have gone from 6b to 7a. Where can I find what new things I can grow??

Heat zone mapping has never been as successful or as widely used as the USDA map based on average coldest winter temperature

There are too many variables when it comes to plant toleration of heat, including humidity, precipitation levels and minimum/maximum night temps in hotter climates.

Also tge duration of heat waves..

Agreed, Dbarron! 20 years ago it was to cold to grow tomatoes outdoors here in Montana and now it's fully doable and a normal thing to grow. On the other hand, this summer I abandoned summertime growing in my greenhouse because it's wayyyy to hot in there nowadays.

Gardeners have a keen and sensitive eye for shifts in the climate. Things have definitely changed in many ways. It's going to be a wild ride as things continue to warm up.

I am now updated to 7B, just outside of NYC in NJ Metro. Flash droughts and flash flooding are going to be the biggest issues for us..., precipitation is now very exaggerated at both ends of the spectrum.

In almost all cases, the zone change was only a half zone increase......from an A to a B or up from a B to the next higher A. That is only a 5 degree increase so to the poster who wondered what they could grow now, the answer is the exact same plants you could grow before. A 5 degree increase in temperature is not going to make a significant difference in what can be grown in that location.

And that is ALL the zonal system indicates - the average low winter temperature. It does not evaluate precipitation or droughts or increased storms.

I’m posting to both map threads: I’m colder now! Last map had me at 6a and now I’m 5b. As you can see from my GW ”handle”, I always planned for 5 anyway. Back when I was a 6a, I’d say if I was a better spitter I could spit into 5b it was so close. I guess I have to change my GW handle.

"Gardeners have a keen and sensitive eye for shifts in the climate. Things have definitely changed in many ways. It's going to be a wild ride as things continue to warm up."

Completely agree, most people are clueless. The Eastern hardiness zones are not without value and it is a crude measure of climate, but better than nothing. As said above, it does not consider rainfall or humidity, or duration of cold or address summer heat issues. The average lows are not average lows for a single season, they are average lows averaged out for a 30 year period, so likely to be much lower than the lowest experienced in any single winter season. From my own personal experience as a sentient being here for some 60 years, I think the data are valid. Decades ago, the extreme, 30 year averaged low, was around -5 to 0 F (so Zone 6b), Now, I am said to be 7b, so average, extreme low of 5 F. and that seems about right. Not a massive difference, no, but would mean survival or death for many species. It is complicated, yes, zones also do not take into consideration..., sun angle, snow cover (which is insulating), DURATION of cold, etc., BUT, if you think it is complicated in the East, the Western climate zones are much more complicated, nuanced, and diverse.

I see more potential problems with the areas that went from up from the B to an A, like around here we went from 4b to 5a. Hardiness is more often only listed by the whole zone, occasionally you will see something like hardy to zone 5b. Not unusual for plants to be suitable to the warmer part of a zone and not the coldest parts. For example, I've been growing several oakleaf hydrangeas for about 7 years now. I've seen them only bloom once, but have been crown hardy all that time. My Itea has only been crown hardy for 6 years now. My Japanese maple sustains damage every year. All plants that are most frequently listed as hardy in zone 5, yet I'm not going to rush out and buy more.

And for Canadians:

https://globalnews.ca/news/10146246/canadas-plant-hardiness-zones-map-ready-to-bloom-for-1st-time-in-10-years/

I find this article to be very confusing. First, it says that the Canadian zonal maps are different than the US's, but says there is an analogue to the US one...., then, it says this.

"Canada’s map does not translate directly to the USDA’s map, but Canada does offer a second map that aligns with the USDA’s single-variable map.

“In some cases, plants are imported and used that are ascribed to the USDA zone and not the Canadian zone. So we’ve done both,” says Dan McKenney, who has played a key role in the maps for decades.

“It’s not the case that the zones are equally sort of transferrable. So, like, a 4a in the Canadian one is like a 5a U.S. one.”

Why would it not be transferrable if it's set on the same parameters?

P.S,, In the US, completely different zonal classification system is used in the West, to take into consideration altitude and microclimates.

P.S., 2: You'll know the climate has changed when your "zone pushing plants", start to self sow and pop up as freakin' WEEDS! LMAO! I saw this with Southern Magnolias, decades ago, they suffered some sun scald, now they self sow and pop up among the oak seedlings and Crape Myrtles, I never planted.

The West is a different creature. I don't think anybody is going to argue about that. However, I gave up on the supposed differences when I compared a USDA map to the AgCanada map in the part of the world I know - around Lake Erie and Lake Ontario. Shockingly, a USDA zone 6, on the south side of the border, merged into an AgCanada zone 6 on the north side. Heading north, everything still seems quite reasonable. So at least in the east, it looks like AgCanada has defined their zones to be the same as the USDA.

I'm a 6, but I have trust issues and only plant stuff rated for 5 and above. Maybe with the zone change, I'll try something rated for zone 6...maybe.

I've been growing zone 8 stuff forever. Most of it survives. As well as the zone 7 stuff does. Maybe I have a microclimate, but honestly, I could do this in two completely different locations, so I don't think so. Maybe I should try to push it to zone 9 stuff!