2023 USDA Zone Map for Florida

[ruskinPalms]

These changes are not unexpected for the most part. I guess I’m officially in 10A now like a lot of us former 9B people on here lol. I have lived here since 2015 and it has only gone below 30F once in that timeframe (Jan 2018) with only maybe a handful of times below 32F with plenty of daytime heating in the winter so it is overall a warm area. I can only vouch for areas I’ve frequented over the years in central Florida mostly. I’m going to say they were too generous with 10A in Polk county, areas outlying Orlando, anywhere near Okeechobee (it gets really cold there! And is only close to 10A right in the lake there by plant observation), pretty much anywhere down off the lake wales ridge, probably went way to far east with 10A along the manatee county and Sarasota county border,  north port is absolutely not 10A (drops into upper 20s yearly there), too generous with 10B in pinellas county, too generous with 10B in the cape haze peninsula, and too generous with 10B in Cape Coral. I do think 10A has definitely expanded in the Tampa area though especially given what palms have made it long term and fruited around here. All this being said, this new map is not going to change what I plan to grow, I not be trying anything more tropical in requirements than a coconut or Adonidia, and I’ll still be looking for interesting palms that supposedly can survive a rare drop into the mid 20s F because that is still my reality here. I think the vast majority of the increases comes from increased suburbanization around the state but I’m sure there are other reasons too. As once wide open cabbage fields are transformed into housing developments with lots of heat leaking structures, concrete, new oak tree plantings per code, creation of retention ponds etc, of course the temps will rise on radiational nights especially. I didn’t see what their methodology was for creating this new map but I very much suspect the combination of real temp readings from official stations and satellite  data of heat maps, vegetation, topography etc. 

[RFun]

  On 11/23/2023 at 12:33 PM, ruskinPalms said:

These changes are not unexpected for the most part. I guess I’m officially in 10A now like a lot of us former 9B people on here lol. I have lived here since 2015 and it has only gone below 30F once in that timeframe (Jan 2018) with only maybe a handful of times below 32F with plenty of daytime heating in the winter so it is overall a warm area. I can only vouch for areas I’ve frequented over the years in central Florida mostly. I’m going to say they were too generous with 10A in Polk county, areas outlying Orlando, anywhere near Okeechobee (it gets really cold there! And is only close to 10A right in the lake there by plant observation), pretty much anywhere down off the lake wales ridge, probably went way to far east with 10A along the manatee county and Sarasota county border,  north port is absolutely not 10A (drops into upper 20s yearly there), too generous with 10B in pinellas county, too generous with 10B in the cape haze peninsula, and too generous with 10B in Cape Coral. I do think 10A has definitely expanded in the Tampa area though especially given what palms have made it long term and fruited around here. All this being said, this new map is not going to change what I plan to grow, I not be trying anything more tropical in requirements than a coconut or Adonidia, and I’ll still be looking for interesting palms that supposedly can survive a rare drop into the mid 20s F because that is still my reality here. I think the vast majority of the increases comes from increased suburbanization around the state but I’m sure there are other reasons too. As once wide open cabbage fields are transformed into housing developments with lots of heat leaking structures, concrete, new oak tree plantings per code, creation of retention ponds etc, of course the temps will rise on radiational nights especially. I didn’t see what their methodology was for creating this new map but I very much suspect the combination of real temp readings from official stations and satellite  data of heat maps, vegetation, topography etc. 

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Yeah, they just could have saved a lot of hassle by choosing longer time frames like 50 or 75 years.  Otherwise, it's a bunch of useless banter every 30 or so years when they release one of these.  Arbor Day's hardiness map from 2015 was already pointing to this.

[flplantguy]

  On 11/23/2023 at 12:33 PM, ruskinPalms said:

These changes are not unexpected for the most part. I guess I’m officially in 10A now like a lot of us former 9B people on here lol. I have lived here since 2015 and it has only gone below 30F once in that timeframe (Jan 2018) with only maybe a handful of times below 32F with plenty of daytime heating in the winter so it is overall a warm area. I can only vouch for areas I’ve frequented over the years in central Florida mostly. I’m going to say they were too generous with 10A in Polk county, areas outlying Orlando, anywhere near Okeechobee (it gets really cold there! And is only close to 10A right in the lake there by plant observation), pretty much anywhere down off the lake wales ridge, probably went way to far east with 10A along the manatee county and Sarasota county border,  north port is absolutely not 10A (drops into upper 20s yearly there), too generous with 10B in pinellas county, too generous with 10B in the cape haze peninsula, and too generous with 10B in Cape Coral. I do think 10A has definitely expanded in the Tampa area though especially given what palms have made it long term and fruited around here. All this being said, this new map is not going to change what I plan to grow, I not be trying anything more tropical in requirements than a coconut or Adonidia, and I’ll still be looking for interesting palms that supposedly can survive a rare drop into the mid 20s F because that is still my reality here. I think the vast majority of the increases comes from increased suburbanization around the state but I’m sure there are other reasons too. As once wide open cabbage fields are transformed into housing developments with lots of heat leaking structures, concrete, new oak tree plantings per code, creation of retention ponds etc, of course the temps will rise on radiational nights especially. I didn’t see what their methodology was for creating this new map but I very much suspect the combination of real temp readings from official stations and satellite  data of heat maps, vegetation, topography etc. 

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They used the PRISM climate group's data.  You can use it to go back in time to extrapolate temps as well in a grid map. Looked fairly accurate from what I saw, I followed my square back through the major freezes and compared the data to what was recorded elsewhere.  I agree about using longer time scales, which is why I had a look for my area to see what it was showing and it seems to match what I see here.  It has changed so much in Florida because the dry sandy soil is so much different than development when it comes to radiational freezes, and advective events are muted compared to before (warmer water and a thicker atmospheric Hadley cell I think).  It's a smaller microcosm with the water nearby so removing the colder spots and replacing with homes has changed things a lot.  Southern California is even more stark of a contrast when you look at the data for lowest temp each year in some areas that had no homes, just citrus, and now are all houses.  Some areas there are 10bish when they were a solid 9b before.  No major arctic blasts there.

[Silas_Sancona]

  On 11/23/2023 at 1:47 PM, flplantguy said:

No major arctic blasts there.

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We get them out here  ..Just a lot more uncommon and -typically- greatly modified by thousands of miles of mountains to the north / northeast before the air mass reaches coastal central and S. Cal / S.W and S. Cen. AZ.  That said, here at least, if deep enough to do so, cold air moving south down / pooled up against the high plains of E. and  S.E. New Mexico can spill west over the divide in S.W. New Mexico / far S.E. AZ,  pool in S.E AZ,  and eventually ( following the general terrain profile between Tucson and Phoenix / Yuma  ) reach this part of the state.. That scenario does seem to have become rarer in recent years though. 

In Cen. / S. Cal, you have to have a large reservoir of cold air pooled in the Central Valley that somehow gets deflected southwest before it is modified, while cutting off any and all possible air mass modification from the Pacific.. to get really cold air into those areas. The infamous, highly amp' ed arctic flavor of Great Basin  " inside sliders "..

Our varied terrain plays a part too.. On the colder nights during one of those outbreaks, sloped areas ( S.W., South, and/ or Southeast facing esp ) can stay ..milder... than valley / canyon bottoms. 

Rule of thumb ..at least in S. Cal used to be ( Might still be, lol )  ." .Where ever there are old, large Laurel Sumac,  you will never / almost never see frost. "  Citrus and Avo. growers used this to their advantage when scoping out productive areas.   Where i'd look for a piece of land too.  Would be a great way for other areas of CA to test just how frost free their area is as well.


 

[flplantguy]

  On 11/23/2023 at 5:32 PM, Silas_Sancona said:

We get them out here  ..Just a lot more uncommon and -typically- greatly modified by thousands of miles of mountains to the north / northeast before the air mass reaches coastal central and S. Cal / S.W and S. Cen. AZ.  That said, here at least, if deep enough to do so, cold air moving south down / pooled up against the high plains of E. and  S.E. New Mexico can spill west over the divide in S.W. New Mexico / far S.E. AZ,  pool in S.E AZ,  and eventually ( following the general terrain profile between Tucson and Phoenix / Yuma  ) reach this part of the state.. That scenario does seem to have become rarer in recent years though. 

In Cen. / S. Cal, you have to have a large reservoir of cold air pooled in the Central Valley that somehow gets deflected southwest before it is modified, while cutting off any and all possible air mass modification from the Pacific.. to get really cold air into those areas. The infamous, highly amp' ed arctic flavor of Great Basin  " inside sliders "..

Our varied terrain plays a part too.. On the colder nights during one of those outbreaks, sloped areas ( S.W., South, and/ or Southeast facing esp ) can stay ..milder... than valley / canyon bottoms. 

Rule of thumb ..at least in S. Cal used to be ( Might still be, lol )  ." .Where ever there are old, large Laurel Sumac,  you will never / almost never see frost. "  Citrus and Avo. growers used this to their advantage when scoping out productive areas.   Where i'd look for a piece of land too.  Would be a great way for other areas of CA to test just how frost free their area is as well.


 

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This is exactly what I was referring to actually.  I went to high school on the high plains of new mexico and the winds with the cold were different than the cold in last Cruces in college.  I actually got to see the damage of the 2007 freeze in San Juan Capistrano at an avocado orchard. The trees low and at the tops were damaged with most in the lowest spots the worst, with the thermal belts fine.  It pools and seeps into all the gaps (or an Albuquerque gap wind event which is terrible in that spot) and builds into a nasty cold pool that lasts for a while.  With the longer track cold events occurring less frequently it can't build just like the Florida freezes don't build up as much cold anymore it seems.  I tried to apply the thermal belts principal when buying land here but it's subtle if it's there at all. 

[ruskinPalms]

I think the 1980s were an anomaly overall and skewed a lot of expectations on these sorts of maps. Not sure what was up with 80s, I grew up as a small child in Indiana in the 80s and it was so bitterly cold every winter. It doesn’t get that cold there anymore.  And I don’t think it got that cold there before the 80s. Maybe there were some volcanic events or something else happening in the 80s to make that decade abnormally cold. Florida was warmer in the not too far past and I’m pretty sure there were commercial growers of various tropical fruits in the Tampa area in the past because the climate supported it. I do think it has warmed beyond Florida’s pre 80s levels though in areas with rapid suburbanization based on what I posted before. And yes I know there were wicked historic freezes before the 80s and yes I think we will see wicked historical level freezes again. But, I think they will be less frequent than the 80s and even less severe in the developed areas because the first night is usually advective (can’t do too much about that except live downwind from a large body of water or have your neat stuff planted on the south side of a substantial structure) and will probably set the record low for the year, but the following radiational nights won’t be as severe as in the past because of the development which as we all know makes radiational nights less of an issue. 

[Silas_Sancona]

  On 11/23/2023 at 6:14 PM, flplantguy said:

This is exactly what I was referring to actually.  I went to high school on the high plains of new mexico and the winds with the cold were different than the cold in last Cruces in college.  I actually got to see the damage of the 2007 freeze in San Juan Capistrano at an avocado orchard. The trees low and at the tops were damaged with most in the lowest spots the worst, with the thermal belts fine.  It pools and seeps into all the gaps (or an Albuquerque gap wind event which is terrible in that spot) and builds into a nasty cold pool that lasts for a while.  With the longer track cold events occurring less frequently it can't build just like the Florida freezes don't build up as much cold anymore it seems.  I tried to apply the thermal belts principal when buying land here but it's subtle if it's there at all. 

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In winter, i always keep an eye out for those back door fronts as they roll south down the plains, just to be sure they don't get hung up in the area where the attendant cold air pool would have an ideal spot to spill west over the divide since it is fairly flat, compared to having a wall of higher peaks to try and over top anyway.... 

In Summer, it's the reverse... Similar back door front events can push extra wet air being drawn northwest from the Gulf of Mexico into AZ, helping to enhance moisture availability for summer storm activity ..and provide a well defined forcing mechanism to get them going.

Some of the strongest storms we can see in the valley often occur when a back door front tries to nose into the state from the northeast during Monsoon Season

Central Valley in CA can have the same " Nasty cool / cold pool that settles and lingers for awhile " issue  when that occurs.. Same kind of event can trigger widespread Tule Fog ..which is just miserable.   If living there, sloped, thermal belt areas bordering the valley would be where i'd look at..

Living in FL during the bigger cold spells was  ...interesting..  I remember watching it go from the upper 70s at 3am, to 50-something in less than a half hour..  The wind as those fronts came through was something else as well.. Can't recall experiencing something similar anywhere else i've lived.   A morning spent in Spring Hill was the first place i'd seen Washingtonia outright killed by the cold either.  Don't recall any in San Jose being killed ..or all that damaged really during the 1990 Arctic air event there ( 19F, lower in other parts of town. ).  Ones in my neighborhood didn't seem to flinch at all for sure.

 

Edited November 23, 2023 by Silas_Sancona
edit

[flplantguy]

The washingtonians dying was weird to me too.  It feels different here and I guess that makes the difference. Moisture maybe?  The weather pattern being a positive vs a negative relative to season is something I noticed this summer too.  Continental airmass is a no for me either way lol.

[Silas_Sancona]

  On 11/23/2023 at 8:27 PM, flplantguy said:

The washingtonians dying was weird to me too.  It feels different here and I guess that makes the difference. Moisture maybe?  The weather pattern being a positive vs a negative relative to season is something I noticed this summer too.  Continental airmass is a no for me either way lol.

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..I think it's the extra moisture there..   Aside from that the air is usually drier here at the same time, " winter " here feels about the same to me as it did while living in both Bradenton and Largo.. Mild or warm, most of the time,  between Dec. and mid Feb,  except during those rare winters where it rains and / or there are more cool spells.   Wore a sweatshirt for at least a week or two in both places at some point between now and ~ roughly~ mid- Feb there..  ...about the same duration i pull one out of a closet here..  In shorts year round regardless.

While i too wouldn't want to live in a continental climate area again, spring, summer and Fall ..and the " typical " parts of winter in KS really weren't awful.   That said, when it got really cold, ..w/ out any snow,  those weeks seemed to last forever.. 

Was at least one year when it tried to get cold ..for about 10 days smack dab in late April.. Reminded me of one of those days at the beach in CA. in late June  when the fog rolls in and the temp. goes from 75-80 to mid 50s and breezy. ( CA native rule of thumb when going to the beach: Always bring a sweatshirt, even if it is 90 and perfectly clear when you get there )   Weird too because it was only the N.E. corner of the state that was chilly / cloudy. Could easily see clear sky just above the horizon when the sun set indicating the rest of the state was basking in typical spring warmth / spring storms.  What happens when a spring storm gets stuck near Chicago and rotates a pool of cool air down from Canada at that time i guess.

[flplantguy]

I remember a heat wave in San Diego that broke like that.  It started as high clouds rolling in off the water at 93 degrees on the beach in oceanside. Then the clouds started to drop, ate the palm heads up high, and finally engulfed the ground, dropping to 70 in minutes. A magical experience for sure and so welcome after that heat.  Eastern New Mexico you traded one harsh weather event for another it seemed.  High wind warnings, dry air on the back of the dry line, cold, heat, hail and severe storms, blizzards and ice storms, fires, thundersnow, a tropical downpour event, it was wild. No outdoor gardening for me if I ever moved back there but it would be as a last resort.  The other side of the mountain though was muted and more possiblity there.  I would not change things here though since every place has trade offs but the heat and freezes and hurricanes you can at least all see coming mostly.

[Ubuntwo]

While Key West is left out of 12a in this revision, parts of the Marquesas Keys get the bump:

Total population of these islands is 0, but it's neat to see 12a make an appearance in the state!

[Aceraceae]

There's a discrepancy between the state and zoomed in zip code maps and, zooming in, on the larger US map, in several states. In at least three cases the local maps leave out a smidge of an higher zone that are on the big map, and the data.

A smidge that comes from local weather stations that show 12a for Key West, 9 for SC GA, 9b or 10a on a tiny south island of Louisiana, as well as a zone 7a spot in SE Michigan. These fair smidges can be seen as a few pixels on the large map but not on the 'more detailed' local maps...

Key West is 12a for 1991 to 2020 or 1995 to present etc. 

Edited February 7, 2024 by Aceraceae

[Cape Garrett]

  On 11/14/2023 at 6:47 PM, RedRabbit said:

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I just noticed this change was made last year.  I do think mostly it is accurate for south and southwest Florida.  I live in Cape Coral on the SW coast and haven't seen a 32 degree low since 2011.  The coldest low I've seen since was one time at 36.   No frosts.  I don't believe all of Brevard county is a 10a.  Not even close.  My brother lives in Titusville maybe a mile or two from the river and he gets frosts every year.  The scraping kind.  Where there are longterm coconuts, christmas palms, carpentarias and veitchias...these areas should have all been considered 10b in the 2012 zone map imo.  I was a 10a.  Now 10b.  Correct.  And Sanibel and Captiva 11a.  I also feel is correct.  Not sure how central and north Florida areas should be.  I just know what I can, and always have been able to grow here in the 22 years I've lived here....zone 10b plants.  The landscape here pretty much mirrors the SE coast of Florida.  Always has.

[kinzyjr]

  On 5/12/2024 at 11:57 AM, Cape Garrett said:

Not sure how central and north Florida areas should be.

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The general consensus is that the 10a zone designation was handed out in a much too generous manner along the I-4 corridor.

[Cape Garrett]

  On 11/23/2023 at 12:33 PM, ruskinPalms said:

These changes are not unexpected for the most part. I guess I’m officially in 10A now like a lot of us former 9B people on here lol. I have lived here since 2015 and it has only gone below 30F once in that timeframe (Jan 2018) with only maybe a handful of times below 32F with plenty of daytime heating in the winter so it is overall a warm area. I can only vouch for areas I’ve frequented over the years in central Florida mostly. I’m going to say they were too generous with 10A in Polk county, areas outlying Orlando, anywhere near Okeechobee (it gets really cold there! And is only close to 10A right in the lake there by plant observation), pretty much anywhere down off the lake wales ridge, probably went way to far east with 10A along the manatee county and Sarasota county border,  north port is absolutely not 10A (drops into upper 20s yearly there), too generous with 10B in pinellas county, too generous with 10B in the cape haze peninsula, and too generous with 10B in Cape Coral. I do think 10A has definitely expanded in the Tampa area though especially given what palms have made it long term and fruited around here. All this being said, this new map is not going to change what I plan to grow, I not be trying anything more tropical in requirements than a coconut or Adonidia, and I’ll still be looking for interesting palms that supposedly can survive a rare drop into the mid 20s F because that is still my reality here. I think the vast majority of the increases comes from increased suburbanization around the state but I’m sure there are other reasons too. As once wide open cabbage fields are transformed into housing developments with lots of heat leaking structures, concrete, new oak tree plantings per code, creation of retention ponds etc, of course the temps will rise on radiational nights especially. I didn’t see what their methodology was for creating this new map but I very much suspect the combination of real temp readings from official stations and satellite  data of heat maps, vegetation, topography etc. 

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Cape Coral is a solid 10b.  Lowest low in the last 13 years has been 36 degrees one time.  Maybe 5 or 6 other times the lows have been in the upper 30s.  Haven't seen a spotty frost since 2011.  When everyone in Florida saw below normal Temps.  Where there are long term coconuts...10b...not 10a.  The difference of vegetation between here and Tampa.  Soo much more tropical here.  Looks like SE Florida since I've lived here for 22 years.  Should have always been 10b imo.  If Tampa was a solid 10a why aren't the streets lined with royal palms and 30 foot plus coconut palms?  Seems like most royals end around the Sarasota area.  Maybe a few miles north unless directly on the coast.  Such a huge vegetative difference from here vs Tampa.  

[RedRabbit]

  On 5/12/2024 at 1:45 PM, Cape Garrett said:

Cape Coral is a solid 10b.  Lowest low in the last 13 years has been 36 degrees one time.  Maybe 5 or 6 other times the lows have been in the upper 30s.  Haven't seen a spotty frost since 2011.  When everyone in Florida saw below normal Temps.  Where there are long term coconuts...10b...not 10a.  The difference of vegetation between here and Tampa.  Soo much more tropical here.  Looks like SE Florida since I've lived here for 22 years.  Should have always been 10b imo.  If Tampa was a solid 10a why aren't the streets lined with royal palms and 30 foot plus coconut palms?  Seems like most royals end around the Sarasota area.  Maybe a few miles north unless directly on the coast.  Such a huge vegetative difference from here vs Tampa.  

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There’s a big difference between Cape Coral and Venice even. It’s something about higher winter highs I think that make the difference.

As far as royal palms go, they’re a cultural symbol of SW Florida so they’re in abundance from Manatee County south. There are a lot in St. Pete and Tampa too, but not a cultural symbol of the region. There are even a lot of public plantings now, with Tampa international airport being one example. Even colder parts of Tampa have some royals.

The absolute cutoff for them seems to be Hudson on the west coast.

[Cape Garrett]

  On 5/12/2024 at 6:10 PM, RedRabbit said:

There’s a big difference between Cape Coral and Venice even. It’s something about higher winter highs I think that make the difference.

As far as royal palms go, they’re a cultural symbol of SW Florida so they’re in abundance from Manatee County south. There are a lot in St. Pete and Tampa too, but not a cultural symbol of the region. There are even a lot of public plantings now, with Tampa international airport being one example. Even colder parts of Tampa have some royals.

The absolute cutoff for them seems to be Hudson on the west coast.

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But overall the Tampa area does not have a vegetative, tropical appearance like down here.  Not even close.  Nor does anywhere in cengral Florida.  That is what I was trying to say.  So agree with others as far as zone change goes, especially in central Florida...don't change what you have been able to successfully grow with minimal damage.  

[Jimbean]

  On 5/12/2024 at 11:57 AM, Cape Garrett said:

I don't believe all of Brevard county is a 10a.  Not even close.  My brother lives in Titusville maybe a mile or two from the river and he gets frosts every year.  The scraping kind.  

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I can tell you first hand that the 10A/9B boundary cuts through Brevard county.  That line is roughly Cape Canaveral, Merritt Island, Rockledge/Melbourne, I-95, then southward.  

I have a lot of complaints about that map.  In my opinion in needs to be trashed.  Especially as someone who can vouch for East Central Florida. 

[RedRabbit]

  On 5/12/2024 at 6:26 PM, Cape Garrett said:

But overall the Tampa area does not have a vegetative, tropical appearance like down here.  Not even close.  Nor does anywhere in cengral Florida.  That is what I was trying to say.  So agree with others as far as zone change goes, especially in central Florida...don't change what you have been able to successfully grow with minimal damage.  

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Yeah, Cape Coral is clearly far better than Tampa. One issue I’ve raised is Carrollwood (North Tampa) and Siesta Key are both 10a. There’s a world of difference between them. Unfortunately, I think any map is going to suffer some issues like that. Even the map I made I wasn’t fully satisfied with some of it.

[kinzyjr]

An app to play with given the new USDA Hardiness Zones:

https://apps.npr.org/plant-hardiness-garden-map/?utm_source=pocket-newtab-en-us

[Silas_Sancona]

  On 5/15/2024 at 10:29 PM, kinzyjr said:

An app to play with given the new USDA Hardiness Zones:

https://apps.npr.org/plant-hardiness-garden-map/?utm_source=pocket-newtab-en-us

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  ...Some minor details i'd question a little, but overall, a pretty accurate map...locally at least..  Nice that you can get in pretty close on specific areas too.

Will be interesting to see what the next couple looks like in 10 or 20 years..

[RedRabbit]

  On 5/15/2024 at 10:29 PM, kinzyjr said:

An app to play with given the new USDA Hardiness Zones:

https://apps.npr.org/plant-hardiness-garden-map/?utm_source=pocket-newtab-en-us

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Great find! That’s fun to play around with and way more user friendly than the actual USDA map.

[Aceraceae]

  On 5/15/2024 at 10:29 PM, kinzyjr said:

An app to play with given the new USDA Hardiness Zones:

https://apps.npr.org/plant-hardiness-garden-map/?utm_source=pocket-newtab-en-us

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  On 5/18/2024 at 4:51 PM, RedRabbit said:

Great find! That’s fun to play around with and way more user friendly than the actual USDA map.

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It's a really cool site that works very well and also allows browsing the full size map. It's an interactive webpage so it works on computers, too. 

It goes by the more zoomed in maps which give Key West as 11b, even though on the US map, zooming in, it accurately has the 12a for the 50.1 F mean min that key west has '91 to '20. And entering Key West on the app it says 'key west low is 50, making it 11b.' If they're rounding down, which zone does 50.0 or 40.0 count as? 

Also in their three example plants they say windmill palm is zone 7 to 11, even though it's more like 8 to 10, or at most a very warm 7 with dry winter but not a scorching summer, or non-desert or non-tropical 11 (SW Europe, some mediterranean type climates). A surprising error, given that they accurately describe hardiness zone elsewhere in the article. A place that regularly get single digits per winter on average, and occasionally goes below 0 (-20 C), is a no go for windmill palm. Even a 7b place like NYC has long freezes and occasional dips to -5 to +5 F (-20 C). Even the tag on plants for sale for profit admit that Trachycarpus is zone 8 with an ultimate low tolerance of around 10 F. 

[kinzyjr]

  On 5/18/2024 at 4:51 PM, RedRabbit said:

Great find! That’s fun to play around with and way more user friendly than the actual USDA map.

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It's fun to peruse around the map at the end in different areas to see where there might be warm and cold pockets in regard to the coldest temperature in the last 30 years.  When I went through Lakeland, most of the interior was around the 24F-25F mark.  My photos after the January 2022 cold event highlighted the difference in palm growing constraints as you travel west from central Lakeland through the more rural areas.  Here is a photo that shows some of the known cold holes on the map:

Tampa/St. Pete: I remember you telling @SubTropicRay how large a difference the short distance between your place and his makes.  Also note the huge difference from Temple Terrace to Downtown Tampa.  The numbers in Temple Terrace are congruent to 1980s-type freeze numbers.

[kinzyjr]

  On 5/12/2024 at 9:45 PM, Jimbean said:

I can tell you first hand that the 10A/9B boundary cuts through Brevard county.  That line is roughly Cape Canaveral, Merritt Island, Rockledge/Melbourne, I-95, then southward.  

I have a lot of complaints about that map.  In my opinion in needs to be trashed.  Especially as someone who can vouch for East Central Florida. 

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You have my nomination to give the State of the USDA Zone Map response.

[Jimbean]

  On 5/19/2024 at 3:01 AM, kinzyjr said:

You have my nomination to give the State of the USDA Zone Map response.

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hahahaha!

[bubba]

The USDA has picked a flawed system to determine plant hardiness. I do not pretend to have the answer because I know that the Koopen system in many ways is equally as flawed.

Please find the entire continental US USDA map:

https://planthardiness.ars.usda.gov

Sorry to beat the drum over and over. How can places in the continental US claim 11a designation when they cannot grow ubiquitous Cocos nucifera, Adonida merrilli, 10 foot Licuala grandis, Pritchardia pacifica, Pritchardaria thrustonia, Cyrtostachhys renda, Areca catchu, Areca vestaria, Neovetchia storckii, Couroupita guianensis, huge Baobab’s Mahogany, Lignum vitae, Dahoon, huge Tamarind, huge Sapodilla’s, Samaan trees all non-stunted and fast growing just to mention a few.

 

[bubba]

[bubba]

[bubba]

[bubba]

[bubba]

[bubba]

[bubba]

[bubba]

What grows!

[SubTropicRay]

  On 5/20/2024 at 2:47 AM, bubba said:

What grows!

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Great photos!  I will say that what grows is transitioning.  Not sure for how long but it's definitely changing.  The current warm stretch (knock on wood) is unprecedented.  If another 40 years pass without a winter (or summer) disaster, parts of central Florida may have similar landscapes.  Not sure I'd bet the house yet though.

On a side note, the rainfall deficit problem could be an effect of this change.

[bubba]

Ray,

Happy you liked the pictures. The point of my post was less Floridacentic and much more about the USDA Plant Hardiness System being flawed on a nationwide scale. 
 

One would assume that in and 11a designation, truly tropical palms and vegetation could be grown ubiquitously. Because the USDA only considers minimum temperatures and avoids the required heat issue, it presents a totally flawed picture.

I do not have enough intricate knowledge of SW Florida to make any broad pronouncements, but certainly know that the Edison estate offers an incredible array of tropical palms and foliage, which likely deserve some thing that approaches 11a. I had the misfortune of spending a large amount of time at Davis Island in Tampa, near Tampa General Hospital, when my oldest son was battling critical Covid. Plenty of coconuts and other vegetation that would register as tropical. This may be a more recent event because I also remember the line of Royal Palms along the Gasparilla Highway and their loss during the 1980 cold events. They should probably replant!

My point is simply that the incredibly broad swath of 11a throughout Southern California does not create the same environment that allows tropical foliage and palms. There even appears to be some areas of the California desert given this designation. None of these areas come close to qualifying for tropical designation under Koppen. None of these areas are capable of growing the tropical specimens that we in the Koppen tropical designation take for granted and are ubiquitous.
 

The vegetation and palms pictured represent a small slice of what grows in this area ubiquitously without pampering. I believe PB receives a 10b designation! That is ludicrous!
Many of these specimens are well over 100 years old, easily handling the 1980 and 1940 cold spells.
 

I cannot devine the future and certainly would not predict weather over the next 40 years. Much of this in our area likely preexists Bartram or earlier. This constitutes a tropical area based upon what grows not dictated solely by minimum temperatures. USDA system is a bird with no wings.

I still do not understand your lack of rainfall. I constantly see references where people appear shocked when it goes dry during the dry season. The wet season always comes. I am certain you have records. When did your region deviate so dramatically from the standard and is this the entire Tampa Bay Area? For how long and why is the press not covering? 
 

 

[RedRabbit]

  On 5/20/2024 at 10:45 AM, SubTropicRay said:

Great photos!  I will say that what grows is transitioning.  Not sure for how long but it's definitely changing.  The current warm stretch (knock on wood) is unprecedented.  If another 40 years pass without a winter (or summer) disaster, parts of central Florida may have similar landscapes.  Not sure I'd bet the house yet though.

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I’ve been getting this sense too. It’s not just the coconuts in places like Bearss Ave, they’ve been known to periodically live in places like that. I feel like I’m seeing native tropicals creeping north too. I’m not sure if it’s just been good luck at this point or if something really changed. 

On the downside, I’m also wondering if the hurricane situation has changed with multiple major hurricanes hitting Florida recently. I thought it was bad luck, but it’s been enough to where I’m not sure now. 
 

  On 5/19/2024 at 12:25 AM, kinzyjr said:

It's fun to peruse around the map at the end in different areas to see where there might be warm and cold pockets in regard to the coldest temperature in the last 30 years.  When I went through Lakeland, most of the interior was around the 24F-25F mark.  My photos after the January 2022 cold event highlighted the difference in palm growing constraints as you travel west from central Lakeland through the more rural areas.  Here is a photo that shows some of the known cold holes on the map:

Tampa/St. Pete: I remember you telling @SubTropicRay how large a difference the short distance between your place and his makes.  Also note the huge difference from Temple Terrace to Downtown Tampa.  The numbers in Temple Terrace are congruent to 1980s-type freeze numbers.

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That’s a neat idea to plot the lowest lows like that and pretty useful. That type of vulnerability is the biggest factor long term.

@SubTropicRay’s area does have a pretty good advantage over mine since it has Tampa Bay to help on radiational nights and a much stronger UHI. I’m not sure if it’s a half zone difference but it could be. I wouldn’t say it’s definitively wrong to have us in the same zone like it is to put Bithlo and Venice in 10a together.

A lot of South Tampa looks quasi-10a (old standard), less tropical than St. Pete which I think is less vulnerable to advective freezes. A few spots in South Tampa look fully z10 though. 

[flplantguy]

I would love a map that shows a fantasy land of what the zones would be without winter arctic air masses and highs bringing colder continental air. What would Orlando be then, possibly even 11b and Miami 12b+? Thats a big difference from those air masses when they come down.  I think even here would be a cool 11a, but still not a Cali 11 with no heat, it would get brutal like summers are trying to be now.

[JLM]

  On 5/21/2024 at 4:10 PM, flplantguy said:

I would love a map that shows a fantasy land of what the zones would be without winter arctic air masses and highs bringing colder continental air. What would Orlando be then, possibly even 11b and Miami 12b+? Thats a big difference from those air masses when they come down.  I think even here would be a cool 11a, but still not a Cali 11 with no heat, it would get brutal like summers are trying to be now.

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If it wasnt for major cold fronts places like Nashville, TN would probably be z8b-9a

I would be z9b-10a. One could only dream.
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I think in order to take the USDA zone map with any value, it should be used in combination with the heat zone map and the Koppen climate classification system to get a better idea of what *could* realistically grow, taking into consideration minimum winter temps, maximum summer temps, and your overall climate whether that be dry or humid. Obviously knowing what grows reliably in your area also certainly helps in this process.