2023 USDA Plant Hardiness Zone Maps Out

[Luis Arroyo]

Haha!😂😂

That's not likely at all... at least not those types of Palms. We might get 8A but will still be subject to the Arctic blast that comes at the very least once every january. But I do see a future where it will be common to see five-10 footer Windmill palms and impressively sized Sabal Minor.

 

Actually that future is here and Zone pusher pioneers like me are leading the way.  I am spreading Windmill and Sable minor Palms seeds throughout south facing sloping Woody areas of New Jersey that are not likely to get developed...like never. Such as Newark area Parks & reservations. 

I plan to seed & plant Windmills & S Minors on the south Atlantic facing hills of Staten Island, NYC.  The geography of that island that makes for interesting microclimates.

[MarcusH]

2 hours ago, Nomad NYC said:

 I'm in south area of the borough of Queens, just a stone's throw away from JFK airport facing Jamaica Bay,  so I wouldn't be surprised if that's my case ( besides microclimates, that would explain why I am able to grow regular Sabal Palmettos outside ).

I do remember as a kid growing up in the '70's in the City,  walking to the school bus stop,  that winters here were much much colder, and huge snowstorms during the season were far more common than now. I'm pretty sure that the New York Metro hardiness area was mapped as Zone 6b back then.

But I believe that It was only around the late '80's that my area of New York  started to transition into Zone 7A.  While I couldn't find any earlier maps showing this, for reference, here is the next best thing with the USDA Hardiness Zones Map for 1990:

 

And here is the related USDA Hardiness interactive Zones Map for 1990 for the NYC Metro region:

Notice that at this time in 1990, most of the five boroughs and the interior of Suffolk county were still Zone 6B,  with most of Long Island a bit warner at 7A.

( One would think that of all the cities of the world, Manhattan at this point time here would demonstrate the Urban Heat Island effect )

 

Now let's look at the map that until recently, most people here in the area ( who were into plants ) referred to - 

 USDA Hardiness interactive Zones Map for 2012 for the NYC Metro region:

....And the USDA Hardiness interactive Zones Map for 2012:

From the above maps, one can see that the 7B warmings trend is now focused on the South West , including small parts of Staten Island and the Bronx , not to mention the Hamptons / Montauk corner in the east part of Long Island. On the other hand, the majority of the Island , the Bronx  and sections of Staten Island were still 7A.

 

Now we come to the present time, with the USDA Hardiness  Zones Map for 2023 for the NYC Metro region:

 

USDA Hardiness interactive Zones Map for 2023 for the NYC Metro region:

As you can tell from the above updated map, most of Long Island , as well as Manhattan, Staten Island, and the Bronx's  and Parts of North Eastern New Jersey are now considered solidly 7B.

So with the recent documentation of this warming trend , if any area here in the NYC metro region begins to become a zone warmer,  I can reasonably assume that I will be right in the middle of it!

 

************************

That being said, while I myself won't live to see it, with the climate being the way it is now, I bet that someday, my descendants could most likely see the below speculative scenes as totally normal :

( That is, if New York City is still here then )

Lol more realistic would be NYCs streets being under water but I really like this picture. 

 

[ChrisA]

On 11/23/2023 at 1:59 PM, WisTex said:

Here are lows and equivalent zones for North Padre island since 1948. 

I'm liking a lot of those North Padre Island #'s!  Hope you get some more 10B or higher winters. You've got a few winters there that were 40f or higher, you should mark those as zone 11A!! Coconut territory!

[Aceraceae]

19 hours ago, ChrisA said:

I'm liking a lot of those North Padre Island #'s!  Hope you get some more 10B or higher winters. You've got a few winters there that were 40f or higher, you should mark those as zone 11A!! Coconut territory!

Yeah for non sub/tropical climates, where rain is in the hot season vs winter, zone 11+ is needed for Coconut palms. 

Mediterranean and desert climates, even when their temps approach tropical, are the opposite of humid sub/tropical climates in precipitation seasonality. Having a hot summer with 0.0 rain then cold rain all winter is bad. San Diego is zone 11 and doesn't have Cocos, or even a very hot summer. The Cali catalina islands are almost zone 12 and don't have tropical palms. There are some zone 12 areas that couldn't grow hot season plants such as subtropical highlands climates, on mountains near the equator, even with good soil and summer rain. A house kept at 68 all year is cool zone 13b, far from San Juan, just like the fridge 10b analogy or the zone 7 freezer analogy. 

Edited November 27, 2023 by Aceraceae

[Silas_Sancona]

23 minutes ago, Aceraceae said:

Yeah for non sub/tropical climates where rain is in the hot season, zone 11+ is needed for Coconut palms. 

Mediterranean and desert climates, even when their temps approach tropical, are the opposite of humid sub/tropical climates in precipitation seasonality. San Diego is zone 11 and doesn't have Cocos. The Cali islands are almost zone 12 and don't have tropical palms. There are some zone 12 areas that couldn't grow hot season plants such as subtropical highlands climates, on mountains near the equator, even with good soil and summer rain. A house kept at 68 all year is cool zone 13b, not like San Juan, just like the fridge 10b analogy or the zone 7 freezer analogy. 

Not totally correct, look at Baja ( Cabo, Todo Santos, La Paz, even San Felipe at the north end of the peninsula.. and places like Hermosillo / Guayamas in Sonora.. Very dry,  ..even if humidity values are better down there compared to here.  Barely any rain, except for a small window during Monsoon / Hurricane season ..if it is a wet year..  Plenty of Coconuts in many areas of each location  ..that fruit too  Numerous other tropicals as well..

San Diego -and many areas around S. Cal- are right on the edge of " Coconut territory " now.  Any planted from ..say today forward,  stand a pretty decent shot of being " within the window " of long term survival shortly.

While climate may influence it as well, a bigger reason there are no tropical-esque palms on any of the Channel Islands( or very few- at best-?  They're a park ..or what non native things are grown in the few settled places, like Avalon or Two Harbors,  is carefully watched.. Don't need to be introducing anything else non native on any of the islands anyway. 

Edited November 27, 2023 by Silas_Sancona
edit

[WisTex]

20 hours ago, ChrisA said:

I'm liking a lot of those North Padre Island #'s!  Hope you get some more 10B or higher winters. You've got a few winters there that were 40f or higher, you should mark those as zone 11A!! Coconut territory!

Too much variability for long term survival.  I think there is a PT member who was having some success until the events of Feb 2021 and Dec 2022 in Flour Bluff area of Corpus Christi, directly across the Laguna Madre from NPI.

Edited November 28, 2023 by WisTex

[Silas_Sancona]

Not sure if had anyone noticed yet, but, Plant Maps has posted the updated USDA map to their more zoom-able site. ..So you can zoom better to specific areas ..with landmarks included too ..Whoo hoo..

CA:









AZ:

[Xenon]

1 hour ago, WisTex said:

Too much variability for long term survival.  I think there is a PT member who was having some success until the events of Feb 2021 and Dec 2022 in Flour Bluff area of Corpus Christi, directly across the Laguna Madre from NPI.

There was a fruiting coconut or two (maybe more) on NPI before the freeze; one belonged to a member of the Palm Society of South Texas, it was already trunking at some point in the late 2000s. There was also a large coconut that had been there since at least 2007 at a house right on the south shore of CC Bay on Ocean Dr. 

[Swolte]

Plant Delights registering discontent on their Facebook account:

=====
Hardiness Har Har

In case you missed it, the USDA just issued their Updated Winter Hardiness Map, led by former PDN/JLBG staffer, Dr. Todd Rounsaville. While the results show an expected warming trend, the results are a bit concerning from the point of view of what plants people will be encouraged to plant. You can find the new map here: https://planthardiness.ars.usda.gov/ 

The new map shows our location outside Raleigh, NC, as moving from Zone 7b to Zone 8a. Since the purpose of the map is to show people what they can grow in each zone, this is troubling. Using a 30 year data set, our winter low temperatures average out to 13.03 degrees F. That temperature is certainly Zone 8a, but when you look at the low temperatures experienced during that 30 year stretch, we experience six years where the temperatures were well below Zone 8a.

During that stretch, we have had:
4 Zone 9a winters, with a low of 20-25 F
7 Zone 8b winters, with a low of 15-20 F
13 Zone 8a winters, with a low of 10-15 F
3 Zone 7b winters, with a low of 5-10 F
2 Zone 7a winters, with a low of 0-5 F
1 Zone 6b winter, with a low of -5-0 F

Therefore on 6 occasions during the last 30 years, all of your Zone 8a plants would have died. Is this really acceptable? We think not.

Having been on the map committee in 2012, we requested that items like this and many other map deficiencies be addressed with the new map, which does not seem to have occurred. If the purpose of the map is simply to show how the low temperature averages have changed on average, then the map works fine, but it is actually used for so much more. I hope the USDA will come up with a plan to address these concerns. 

Edited November 28, 2023 by Swolte

[RFun]

3 hours ago, Swolte said:

Plant Delights registering discontent on their Facebook account:

=====
Hardiness Har Har

In case you missed it, the USDA just issued their Updated Winter Hardiness Map, led by former PDN/JLBG staffer, Dr. Todd Rounsaville. While the results show an expected warming trend, the results are a bit concerning from the point of view of what plants people will be encouraged to plant. You can find the new map here: https://planthardiness.ars.usda.gov/ 

The new map shows our location outside Raleigh, NC, as moving from Zone 7b to Zone 8a. Since the purpose of the map is to show people what they can grow in each zone, this is troubling. Using a 30 year data set, our winter low temperatures average out to 13.03 degrees F. That temperature is certainly Zone 8a, but when you look at the low temperatures experienced during that 30 year stretch, we experience six years where the temperatures were well below Zone 8a.

During that stretch, we have had:
4 Zone 9a winters, with a low of 20-25 F
7 Zone 8b winters, with a low of 15-20 F
13 Zone 8a winters, with a low of 10-15 F
3 Zone 7b winters, with a low of 5-10 F
2 Zone 7a winters, with a low of 0-5 F
1 Zone 6b winter, with a low of -5-0 F

Therefore on 6 occasions during the last 30 years, all of your Zone 8a plants would have died. Is this really acceptable? We think not.

Having been on the map committee in 2012, we requested that items like this and many other map deficiencies be addressed with the new map, which does not seem to have occurred. If the purpose of the map is simply to show how the low temperature averages have changed on average, then the map works fine, but it is actually used for so much more. I hope the USDA will come up with a plan to address these concerns. 

Whoever made this statement is making assumptions that all "zone 8a plants" would have died there.  How do you define "zone 8a plants"?  That can mean different things to different people.  Anyway, in practical terms, that simply isn't the case by looking at recent pictures I've seen.  Again, it's hard to make assumptions based on concepts and not practical, real life situations.  Again, look at places like Gary's Nursery in New Bern, NC.  He experienced -4F.  Wilmington, NC has seen 0F.  The coldest temp I am showing for Raleigh in that stretch is 0F (that is 7a as 7a begins at 0F).  Does this person really believe this?  If so, what were they even doing on that 2012 committee?

Edited November 28, 2023 by RFun

[sebastian_inlet]

3 hours ago, RFun said:

Whoever made this statement is making assumptions that all "zone 8a plants" would have died there.  How do you define "zone 8a plants"?  That can mean different things to different people.  Anyway, in practical terms, that simply isn't the case by looking at recent pictures I've seen.  Again, it's hard to make assumptions based on concepts and not practical, real life situations.  Again, look at places like Gary's Nursery in New Bern, NC.  He experienced -4F.  Wilmington, NC has seen 0F.  The coldest temp I am showing for Raleigh in that stretch is 0F (that is 7a as 7a begins at 0F).  Does this person really believe this?  If so, what were they even doing on that 2012 committee?

In a previous location, I lost a healthy Chicago Hardy Fig, despite it being heavily mulched, due to a Zone 6b winter. The plant was supposed to survive in Zone 5 or 6, depending on the seller's information. Often, nurseries tend to overestimate the hardiness of their plants. The USDA labeled the area as Zone 6a, bordering on Zone 5b in the 2012 map. Aware of its potential vulnerability with the 2012 map near Zone 5b, I suspected it might not survive.

However, the updated map now shows it as Zone 6b, possibly misleading newer gardeners into assuming it should survive. Just a couple of years ago, we experienced a winter akin to Zone 5b. When these maps are released, thorough criteria reviews should be conducted. It's plausible that some nurseries factored in the warming trend while suggesting cold hardiness. Now there is even greater disparity between nursery ratings and USDA map. 

The more significant issue lies with the 10a zone. Almost half of Florida was categorized as 10a based on a 30-32°F range. However, the majority of 10a locations in the 2012 map rarely experienced frost. Presently, these new locations encounter frost almost annually. Consequently, a location reaching 28°F one year and 32°F the next could be deemed a 10a location, despite 28°F being detrimental to many tropical trees. Now, someone could make the argument gardeners should plant one zone lower which would mean what could be a 10a tree needs to be planted in a zone 11.  Zone 11 is a unicorn, it barely exist.  If gardeners go with planting 10a trees in a 10b location, 10b locations in 2023 map are also covering much less than 10a locations in 2012 map.  As a result, they made the Florida map almost useless.  In 2012, they used the years from 1976 to 2005.  They could have used in the new map 1985 to 2015 data just to give less weight on the warming climate which would not paint half of the Florida as 10a. 

Furthermore, the maps did not include frost data from 2020 to 2023. A more careful approach in their assessment would have been beneficial. You can make the argument that it is responsibility of the gardener to check their zone and their plants more careful. But all idea about this USDA map was to help gardeners with limited knowledge. 

Edited November 29, 2023 by sebastian_inlet

[RFun]

2 hours ago, sebastian_inlet said:

In a previous location, I lost a healthy Chicago Hardy Fig, despite it being heavily mulched, due to a Zone 6b winter. The plant was supposed to survive in Zone 5 or 6, depending on the seller's information. Often, nurseries tend to overestimate the hardiness of their plants. The USDA labeled the area as Zone 6a, bordering on Zone 5b in the 2012 map. Aware of its potential vulnerability with the 2012 map near Zone 5b, I suspected it might not survive.

However, the updated map now shows it as Zone 6b, possibly misleading newer gardeners into assuming it should survive. Just a couple of years ago, we experienced a winter akin to Zone 5b. When these maps are released, thorough criteria reviews should be conducted. It's plausible that some nurseries factored in the warming trend while suggesting cold hardiness. Now there is even greater disparity between nursery ratings and USDA map. 

The more significant issue lies with the 10a zone. Almost half of Florida was categorized as 10a based on a 30-32°F range. However, the majority of 10a locations in the 2012 map rarely experienced frost. Presently, these new locations encounter frost almost annually. Consequently, a location reaching 28°F one year and 32°F the next could be deemed a 10a location, despite 28°F being detrimental to many tropical trees. Now, someone could make the argument gardeners should plant one zone lower which would mean what could be a 10a tree needs to be planted in a zone 11.  Zone 11 is a unicorn, it barely exist.  If gardeners go with planting 10a trees in a 10b location, 10b locations in 2023 map are also covering much less than 10a locations in 2012 map.  As a result, they made the Florida map almost useless.  In 2012, they used the years from 1976 to 2005.  They could have used in the new map 1985 to 2015 data just to give less weight on the warming climate which would not paint half of the Florida as 10a. 

Furthermore, the maps did not include frost data from 2020 to 2023. A more careful approach in their assessment would have been beneficial. You can make the argument that it is responsibility of the gardener to check their zone and their plants more careful. But all idea about this USDA map was to help gardeners with limited knowledge. 

Some nurseries may overestimate the hardiness for sales, but I've found most people underestimate the hardiness of most plants.  Too many people don't give any leeway with hardiness zones.  They just assume a zone 8a can never experience colder winters and vice versa.  There has to be leeway there or we wouldn't be seeing many plants in their current locations if it were based on an entirely inflexible model.

Edited November 29, 2023 by RFun

[L.A.M.]

I'm now a few miles from the 7a/7b border but officially in 7b. (I was previously a solid 7a.) My yard is probably still a solid 7a for all intents and purposes, though, given the elevation (which is actually the same as many officially 7a areas further east) and my sky-exposed, wind-sheltered microclimate (which leads to diurnal and seasonal temperature extremes measurably worse than my general climate).

[teddytn]

On 11/28/2023 at 12:31 PM, Swolte said:

Plant Delights registering discontent on their Facebook account:

=====
Hardiness Har Har

In case you missed it, the USDA just issued their Updated Winter Hardiness Map, led by former PDN/JLBG staffer, Dr. Todd Rounsaville. While the results show an expected warming trend, the results are a bit concerning from the point of view of what plants people will be encouraged to plant. You can find the new map here: https://planthardiness.ars.usda.gov/ 

The new map shows our location outside Raleigh, NC, as moving from Zone 7b to Zone 8a. Since the purpose of the map is to show people what they can grow in each zone, this is troubling. Using a 30 year data set, our winter low temperatures average out to 13.03 degrees F. That temperature is certainly Zone 8a, but when you look at the low temperatures experienced during that 30 year stretch, we experience six years where the temperatures were well below Zone 8a.

During that stretch, we have had:
4 Zone 9a winters, with a low of 20-25 F
7 Zone 8b winters, with a low of 15-20 F
13 Zone 8a winters, with a low of 10-15 F
3 Zone 7b winters, with a low of 5-10 F
2 Zone 7a winters, with a low of 0-5 F
1 Zone 6b winter, with a low of -5-0 F

Therefore on 6 occasions during the last 30 years, all of your Zone 8a plants would have died. Is this really acceptable? We think not.

Having been on the map committee in 2012, we requested that items like this and many other map deficiencies be addressed with the new map, which does not seem to have occurred. If the purpose of the map is simply to show how the low temperature averages have changed on average, then the map works fine, but it is actually used for so much more. I hope the USDA will come up with a plan to address these concerns. 

Recent video posted with Tony Avent from PDN/JLBG in regards to the new hardiness map changes

[Las Palmas Norte]

50 minutes ago, teddytn said:

Recent video posted with Tony Avent from PDN/JLBG in regards to the new hardiness map changes

From that video it's looking like Tony's best recommendation is to use the 1990 map for reliability.  Kinda makes sense for a variety of reasons.

[Paradise Found]

Wow!!! I check my zip code and it says I am in a solid 8b now.  I’m not to surprised but thankful it is.  Anyone else go up in PNW?
 

Edited December 6, 2023 by Paradise Found

[Trustandi]

Nice @Paradise Found! I am in 9a now. 

[Paradise Found]

42 minutes ago, Trustandi said:

Nice @Paradise Found! I am in 9a now. 

Awesome man.  There’s going to be a lot more marine time 9a I am sure of that!

Edited December 6, 2023 by Paradise Found

[teddytn]

13 hours ago, Las Palmas Norte said:

From that video it's looking like Tony's best recommendation is to use the 1990 map for reliability.  Kinda makes sense for a variety of reasons.

It really is the best advice. Get a core group of plants that are solid for your zone and by zone I mean plan for the worst winters you “could” get. And then start experimenting from there. Whats the old saying “plan for the worst, hope for the best”

[L.A.M.]

On 12/5/2023 at 6:08 PM, Las Palmas Norte said:

From that video it's looking like Tony's best recommendation is to use the 1990 map for reliability.  Kinda makes sense for a variety of reasons.

I disagree. On paper, that does seem like good advice. Nonetheless, the 1990 map doesn't really take into account elevation or maritime moderation, at least not anywhere good enough. In the 1990 map, Cookeville was 6a, but Crossville was nominally 6b and Clingmans Dome nominally 6a despite both obviously being colder. On the other hand, the 2012 map was so detailed that it even included milder microclimates downwind of major lakes; Guntersville was marginally 8a but completely surrounded by 7b on that map.

I think a better protocol would be to use the 2012 map and subtract half a zone or, better still, the 2023 map and subtract a full zone, except if you have a decent microclimate to plant things in and/or are along the warmer margin of whatever half-zone you're in (in which case you can add a half-zone above your calculated result for shade-tolerant native plants). The 1990 map has terrible resolution, not to mention that some areas like the southeastern quarter of Tennessee have warmed especially fast while some others like south-central Oklahoma and the Texas Panhandle haven't warmed much (if any) at all.

P.S.: Also, if you live along the coastal plain of the Mid-Atlantic USA or Cape Cod. . . .well, good luck once Greenland thaws. I've read that the melting of the Laurentide Ice Sheet supercharged the Labrador Current, allowing permafrost to form as far south as Jacksonville (the Carolina Bays we see now are from thawed permafrost) - even though the Gulf Coastal Plain doesn't have evidence of old permafrost west of the Florida Panhandle, not even in the Mississippi Embayment in Southern Illinois which was literally a few dozen miles from the ice sheet at times. (The consensus is that the Critchfield spruce that once dominated Tennessee and Louisiana was most likely a temperate spruce species like white spruce and Norway spruce are today.) Once Greenland thaws, it'll likely supercharge the Labrador Current again and put anyone living near sea level north of Cape Hatteras in a subarctic or even tundra climate until the thaw completes. The seafloor along that coast still has the marks from where icebergs were pushed south before.

Edited December 11, 2023 by L.A.M.

[RFun]

Just go to weather.gov and look at the average minimum temperature for a good 50 or 75 year stretch to get a good gauge.  No need to over complicate this.  You can always add protection if you need to.  Certain varieties of palms don't tend get so tall that a 16 foot step ladder couldn't handle the job.

[Las Palmas Norte]

3 hours ago, RFun said:

Just go to weather.gov and look at the average minimum temperature for a good 50 or 75 year stretch to get a good gauge.  No need to over complicate this.  You can always add protection if you need to.  Certain varieties of palms don't tend get so tall that a 16 foot step ladder couldn't handle the job.

The long game is fundamental for the bones of an exotic garden, even on occasion some of those plantings can be compromised and succumb to a bad winter. I stopped telling myself stories and believing in long term milder winters after loosing too many plants in the 40 plus years I've been involved in exotics. 

[PalmsNC]

12 hours ago, L.A.M. said:

I disagree. On paper, that does seem like good advice. Nonetheless, the 1990 map doesn't really take into account elevation or maritime moderation, at least not anywhere good enough. In the 1990 map, Cookeville was 6a, but Crossville was nominally 6b and Clingmans Dome nominally 6a despite both obviously being colder. On the other hand, the 2012 map was so detailed that it even included milder microclimates downwind of major lakes; Guntersville was marginally 8a but completely surrounded by 7b on that map.

I think a better protocol would be to use the 2012 map and subtract half a zone or, better still, the 2023 map and subtract a full zone, except if you have a decent microclimate to plant things in and/or are along the warmer margin of whatever half-zone you're in (in which case you can add a half-zone above your calculated result for shade-tolerant native plants). The 1990 map has terrible resolution, not to mention that some areas like the southeastern quarter of Tennessee have warmed especially fast while some others like south-central Oklahoma and the Texas Panhandle haven't warmed much (if any) at all.

P.S.: Also, if you live along the coastal plain of the Mid-Atlantic USA or Cape Cod. . . .well, good luck once Greenland thaws. I've read that the melting of the Laurentide Ice Sheet supercharged the Labrador Current, allowing permafrost to form as far south as Jacksonville (the Carolina Bays we see now are from thawed permafrost) - even though the Gulf Coastal Plain doesn't have evidence of old permafrost west of the Florida Panhandle, not even in the Mississippi Embayment in Southern Illinois which was literally a few dozen miles from the ice sheet at times. (The consensus is that the Critchfield spruce that once dominated Tennessee and Louisiana was most likely a temperate spruce species like white spruce and Norway spruce are today.) Once Greenland thaws, it'll likely supercharge the Labrador Current again and put anyone living near sea level north of Cape Hatteras in a subarctic or even tundra climate until the thaw completes. The seafloor along that coast still has the marks from where icebergs were pushed south before.

The coast always has been and always will be milder than inland Tennesse, I am not sure where you are getting any of this from. The east coast wasn't tundra while inland was temperate... more like the opposite hence why the ice sheet came so much further south. We see it yearly with powerful arctic fronts bringing places west of the apps like Tennessee down to -5-0 degrees while it never drops below 10 east of those mountains and barely below 20 along the coast.

[L.A.M.]

On 12/11/2023 at 4:02 PM, PalmsNC said:

The coast always has been and always will be milder than inland Tennesse, I am not sure where you are getting any of this from. The east coast wasn't tundra while inland was temperate... more like the opposite hence why the ice sheet came so much further south. We see it yearly with powerful arctic fronts bringing places west of the apps like Tennessee down to -5-0 degrees while it never drops below 10 east of those mountains and barely below 20 along the coast.

Maybe while the ice sheet was at its peak and/or during winter. I meant overall/during summer while the ice sheet was thawing, though, the supercharged Labrador Current cooled the coast enough to form permafrost there. I don't quite understand how there wasn't any permafrost in the Gulf Coastal Plain either, but my guess is there was probably a strong marine layer like coastal California has during summer. The Appalachian Piedmont and Florida Peninsula would've blocked that marine layer. Inland, evidence of permafrost has only been found a few dozen miles from the terminal moraine itself at most in places like Kentucky, Southern Illinois and the Missouri Ozarks, suggesting a strong latitudinal gradient as the jet stream trapped the frigid continental air over and immediately around the ice sheet except out West (where we know permafrost extended further south in the Northwest and the Southwest wasn't so dry like it is now). The events where the Labrador Current became supercharged were called "Heinrich events."

Anyways, though, I would suggest subtracting a full zone from the 2023 (or half a zone if you're near the warmer end and/or using shade-tolerant native plants) for people not along the East Coast north of Cape Hatteras, simply out of caution. Some areas have only gone up half a zone from 1990 while others have gone up a full zone, and the 1990 map lacked the precision the 2012 and 2023 ones; using the 1990 map as a cautionary guide unless of just subtracting a zone from your 2023 one would be too limiting in areas that warmed slowly and/or have a lake effect/sea breeze and not go far enough in some areas at higher elevations. For those coastal areas, though, probably not much you can do long-term other than plant white spruce and other plants able to take a wide variety of climates; another Heinrich event is virtually certain now that Greenland's ice sheet is past the point of no return.

Edited December 12, 2023 by L.A.M.

[SeanK]

On 11/26/2023 at 8:29 PM, Luis Arroyo said:

Haha!😂😂

That's not likely at all... at least not those types of Palms. We might get 8A but will still be subject to the Arctic blast that comes at the very least once every january. But I do see a future where it will be common to see five-10 footer Windmill palms and impressively sized Sabal Minor.

 

Actually that future is here and Zone pusher pioneers like me are leading the way.  I am spreading Windmill and Sable minor Palms seeds throughout south facing sloping Woody areas of New Jersey that are not likely to get developed...like never. Such as Newark area Parks & reservations. 

I plan to seed & plant Windmills & S Minors on the south Atlantic facing hills of Staten Island, NYC.  The geography of that island that makes for interesting microclimates.

Spread the S.minors down in the pine barrens and swampy areas.

[L.A.M.]

On 12/13/2023 at 11:44 AM, SeanK said:

Spread the S.minors down in the pine barrens and swampy areas.

That's exactly what I'm trying to do here in Tennessee. We already have little-known wild ones in a few of the southern border counties (similarly to Oklahoma and Virginia), but they're not present in the Nashville/Murfreesboro or Cookeville areas except wherever people plant them. Kudzu starts in the understory before an opening in the canopy lets it thrive, so we need competition in places that have poorly-draining soil, juglone and shade to keep struggling young kudzu patches in check while we still can. Then the palmetto seeds will also feed many of our wild birds and mammals, including bears. Last but not least, a variety and abundance of green foliage during winter is an antidote to seasonal depression from my experience. Really, we need our canebrakes and pine savannas back, but planting palmbrakes could also be helpful in more ways than one.

Edited December 15, 2023 by L.A.M.

[SeanK]

There is a pond near me that is accessible now that trees have gone bare. I need to clear orr some S.minor seed.

[sebastian_inlet]

So much to say 10A/10B for Brownsville, South Padre Island tx ...

This is one year but, 10B = 35F average minimum
temperatures ...Yesterday 28 F lows according to this website:

 

How USDA published such map .... 

Edited January 17 by sebastian_inlet

[RFun]

7 hours ago, sebastian_inlet said:

So much to say 10A/10B for Brownsville, South Padre Island tx ...

This is one year but, 10B = 35F average minimum
temperatures ...Yesterday 28 F lows according to this website:

 

How USDA published such map .... 

Those maps are based on averages.  Some years will be higher or lower than the average.  Again, leeway needs to be taken into consideration.  Notice also how short those cold snaps last in the Brownsville area.  That is yet another key factor in the plants that you are able to see there.

[SeanK]

On 1/17/2024 at 6:20 AM, RFun said:

Those maps are based on averages.  Some years will be higher or lower than the average.  Again, leeway needs to be taken into consideration.  Notice also how short those cold snaps last in the Brownsville area.  That is yet another key factor in the plants that you are able to see there.

The maps are based on the -3 sigma number for average minimums.

[Harry’s Palms]

Elevation and location of property can be significant if you are on the edge of your zone. Over 25 years ago I moved from the flat , almost sea level part of the city to a hill about 350’ high and south facing. The temperature difference in winter is about 3-4 degrees f. The frost usually starts on the roof tops about half way down the hill. I have seen frost up here on the north side of the street but very rare. My zone is a 9b but more like a 10a in actuality. Not that much different but enough to allow for a couple of varieties that would not survive at my old house. 

[DTS]

I found all the cold 7a pockets in Michigan



Still doesn't say michigan is 7a in the full map, though.

[joetx]

Round Rock, TX now in 9a! Just need the Polar Vortex to stop misbehaving! 

[MarcusH]

7 hours ago, joetx said:

Round Rock, TX now in 9a! Just need the Polar Vortex to stop misbehaving! 

Yep tell me about it