How possible is this projected hardiness zone map?

[Pee Dee Palms]

Seeing Myrtle Beach as 8b and Virginia Beach as 9a seems super unlikely this far into the future. Does anyone know if this is a reputable projected hardiness zone map? 

[Jimbean]

It's just that, it's based on a projection.  I don't know exactly what numbers they are plugging in, but I'd take it with a grain of sand. 

[ruskinPalms]

I’d say just stick with the historical map for any future planting plans.

[chinandega81]

For that map to be accurate, the world would have to be a much, much warmer place. I see that is the high end estimate. What is the mid and low range map estimate showing?

[Teegurr]

On 11/19/2021 at 6:15 PM, chinandega81 said:

For that map to be accurate, the world would have to be a much, much warmer place. I see that is the high end estimate. What is the mid and low range map estimate showing?

We're already nearing the higher scenario. The historical map isn't accurate anymore, but the higher scenario is not quite accurate either. For example, Miami is already well into 11a (not 10b), but Daytona Beach isn't quite 10a (it's right on the border, with an annual average minimum of 30).

Let's look at the outdatedness of the historical map.

It says New Orleans, LA is 9a (it's 9b)

Augusta, GA is not 8a (it's 8b)

Birmingham, AL is not 7b (it's 8a)

However, the new map isn't accurate yet for many locations either.

For example, Louisville, KY is currently a 7a climate. The map projects it will be 8a in 50-70 years. This is a bit drastic, but it's possible. Same for Fayetteville, AR.

Nashville is currently a 7b climate. The map projects it will be 8b in 50-70 years. Not sure about this one.

Charleston is currently a weak 9a climate. The map projects it will be 9b in 50-70 years. That's believable.

Myrtle Beach is 8b/9a currently. The map predicts it will be 8b. That's probably an underestimate.

Virginia beach is 8b currently. The map predicts it will be 9a. Seems reasonable, but why is VB 9a and MB 8b?

Overall, I don't think the projected map is a large overestimate, especially since it's projecting 50-70 years into the future. However, I think the map is most likely to overestimate the north's warming. With that being said, the north is warming faster than the south. 

 

[Silas_Sancona]

1 hour ago, Teegurr said:

We're already nearing the higher scenario. The historical map isn't accurate anymore, but the higher scenario is not quite accurate either. For example, Miami is already well into 11a (not 10b), but Daytona Beach isn't quite 10a (it's right on the border, with an annual average minimum of 30).

 

Overall, I don't think the projected map is a large overestimate, especially since it's projecting 50-70 years into the future. However, I think the map is most likely to overestimate the north's warming. With that being said, the north is warming faster than the south. 

 

^^ Agree w/ this .. Suggested maps may be " in the ballpark ", but not quite a home run.. Saw these and other maps from other parts of the country from the same source and  share a similar level of " we'll see how this plays out " kind of thoughts about the outcome portrayed.

California, S. Cal in particular, already has areas of 11a No doubt those will continue to expand. Could some lucky spots flirt w/ 12a in the future? Possible, ..we'll see.   Could Tucson, now borderline 9a/b in many areas,  lower / middle 9b in the warmest spots  see several solid 10 ..or even flirting w/ 10b winters in a row? ..possible, but that may be x number of years outside the suggested timeline. Those warmer winters come with consequences though ..less ( or many winters w/ out any Snow in the mountains, since they'll warm too ) and a warm winter only sets the stage for a hotter summer, sooner..  Tropical stuff that might do fine in the winter, may not withstand the summer sizzle, esp. those summers when our monsoon rains are sparse or fail to materialize all together.  ..Unless some of the projections of somewhat wetter summers end up panning out, compared to the opposite suggested in other projections.

As i have mentioned before, watch the critters,  both locally native and those native to the south of your location which might have been rare sights in years past in your particular location. Do these " rarer and perhaps more exotic creatures " stay around longer and longer into the Fall? appear sooner in the spring?  remain year round?   ..are they able to reproduce in your location now?  Do X bird / insect / other critter species, native to warmer areas to the south seem to be becoming more common, while the critters that have been familiar sights for x years seem to be decreasing in number ( as they move north or seek out higher and cooler habitats ) 

..How are plants that may have frozen to the ground yearly but now might rarely suffer fatal damage, and/ or weren't able to reproduce more successfully doing now?  Native stuff seem to be struggling w/ the hotter summers, during drier years, insects a touch more in recent years ..or in coming years? 

These are the things to keep your eyes on that provide more accurate clues related to warming hardiness zones. While the overall trend  is  up, Temperatures will always vary year to year and, while many may be milder, overall, some winters will still be cold,  a couple may be seemingly brutal  scattered among many that are flat out warm  ..just maybe not quite as cold as they could have been, minus the slow but steady on-going warming trend.

 

[GottmitAlex]

I think they should update the USDA hardiness zone map. 

I think we are still based on 2012.

[Silas_Sancona]

1 minute ago, GottmitAlex said:

I think they should update the USDA hardiness zone map. 

I think we are still based on 2012.

Bet it gets updated in the next year or two, after PRISM releases the latest 30 yr update ( supposed to be released < after lots of delay > sometime next month ) USDA map isn't all that great on finer detailed data, esp. in the west anyway.

[GottmitAlex]

3 hours ago, Silas_Sancona said:

Bet it gets updated in the next year or two, after PRISM releases the latest 30 yr update ( supposed to be released < after lots of delay > sometime next month ) USDA map isn't all that great on finer detailed data, esp. in the west anyway.

Quite right! I mean, Coconuts in this region since 2016? Yeah, they're going to have to to work on the fine details. 

 

[UK_Palms]

East central London is officially listed a 10a zone, but I can see the rest of central London being bumped up to 10a soon and the rest of London becoming a solid 9b. Don't take these zonal markings as gospel as they obviously just give a rough idea. I'm pretty sure there were no 10a zones 50 years ago though. And no 9b zones 100 years ago.

 

Scorpions are living in the UK now. An estimated 10,000 - 15,000 specimens in Kent alone. Another 5,000 in east London. By far the furthest north scorpion population in the world. I'm not sure where these came from but they definitely aren't endemic to the UK. The same with false widow spiders that came here from the Canary Islands and are venomous. False widows are now my most common spider here and have displaced all other spiders. They will eat my native species. A bite from a false widow isn't fatal, but it will cause your hand to swell up and venom can eat through quite a bit of skin and cause some necrosis. 

 

These Aesculapian snakes definitely aren't native either but are beginning to take over the London waterways. Some pretty good footage here of them in London this September. I think they came from Spain or Italy and are breeding out of control in recent years. The birds are disappearing in parts of London where they are present. More evidence of a changing climate and increasing hardiness zone, given that these snakes and scorpions are thriving there. Heaven forbid someone introduces some rattle snakes of some kind. There are already gators and snapping turtles living in the Thames water ways that have been dumped or escaped. Every year they pull some out. If they didn't I am sure they would reproduce. 

 

With all the palm trees such as CIDP, Washingtonia and Brahea appearing over the past two decades, as well as scoprions, snakes and spiders, it does make you wonder what London and southern England will be like in another decade or two from now. Here's the latest street view update on the East Dulwich washingtonia in south London. Still not even in the top 5 biggest London washies, but a decent size nonetheless. Something you never would have seen just 10-20 years ago. Clearly indicative of a changing climate and an ever-expanding UHI.

 

[Jimbean]

47 minutes ago, UK_Palms said:

East central London is officially listed a 10a zone, but I can see the rest of central London being bumped up to 10a soon and the rest of London becoming a solid 9b. Don't take these zonal markings as gospel as they obviously just give a rough idea. I'm pretty sure there were no 10a zones 50 years ago though. And no 9b zones 100 years ago.

 

Scorpions are living in the UK now. An estimated 10,000 - 15,000 specimens in Kent alone. Another 5,000 in east London. By far the furthest north scorpion population in the world. I'm not sure where these came from but they definitely aren't endemic to the UK. The same with false widow spiders that came here from the Canary Islands and are venomous. False widows are now my most common spider here and have displaced all other spiders. They will eat my native species. A bite from a false widow isn't fatal, but it will cause your hand to swell up and venom can eat through quite a bit of skin and cause some necrosis. 

 

These Aesculapian snakes definitely aren't native either but are beginning to take over the London waterways. Some pretty good footage here of them in London this September. I think they came from Spain or Italy and are breeding out of control in recent years. The birds are disappearing in parts of London where they are present. More evidence of a changing climate and increasing hardiness zone, given that these snakes and scorpions are thriving there. Heaven forbid someone introduces some rattle snakes of some kind. There are already gators and snapping turtles living in the Thames water ways that have been dumped or escaped. Every year they pull some out. If they didn't I am sure they would reproduce. 

 

With all the palm trees such as CIDP, Washingtonia and Brahea appearing over the past two decades, as well as scoprions, snakes and spiders, it does make you wonder what London and southern England will be like in another decade or two from now. Here's the latest street view update on the East Dulwich washingtonia in south London. Still not even in the top 5 biggest London washies, but a decent size nonetheless. Something you never would have seen just 10-20 years ago. Clearly indicative of a changing climate and an ever-expanding UHI.

 

 

That map is not right

[UK_Palms]

8 minutes ago, Jimbean said:

That map is not right

Can you expand on that a bit. The map lists my area as 8b, which is correct. Most of London is shown as 9a, which again is correct. Central and eastern London is 9b, which again is correct. The only argument is that there is no true 10a zone in the mildest part of east central London. However that area has not dropped below 35F in 2 of the past 3 winters there, which suggests it may actually be 10a. I mean there is decent sized Bougainvillea growing there, which struggles in northern Florida winters.

I'm pretty sure you would need at least a 9b or 10a climate to get Bougainvillea of this size growing like this up at 51N. You certainly wouldn't get it growing like that in an 8b or 9a zone, so that part of London has to be 9b or 10a. Most of the southern coastline of England is 9b as well with 10a in places. I think Tresco on the Isles of Scilly off the coast of Cornwall is a 10b zone most years, but that spot is in a different league for exotics. The lowest on Tresco last winter was 36F I believe, and that was the coldest winter of the past 3. 

Dagenham Bougainvillea in east London at 51N. Picture taken this August/September. Definite 9b / 10a zone. 

[Jimbean]

I'd have to look at the numbers, but I find that hard to believe that it would be anywhere close to 10A there.  I can't imagine royals in London other than the family haha

[Pee Dee Palms]

Wow! Wasn't expecting this post to blow up as much as it did! I have been noticing that the Common Conehead Katydids (a grasshopper like insect) have been slowly dwindling away. I am a insect and arachnid enthusiast and own the world's deadliest scorpion (Androctonus australis, Yellow Fat-tail Scorpion) along with 4 more various species of scorpions. Don't know why any of you would need to know that but every arachnid owner has to tell people about their weird addiction lol. Anyway, back onto subject, in the past years I have seen these Conehead Katydids pretty commonly. I have noticed in 2019 and 2020 they have started to disappear rapidly. This year I have only seen just a tad few. I took a trip up to Table Rock State Park near the very northwest of South Carolina (Zone 7b). When I was there I noticed far more Katydids than the past years, as if they have migrated. I also saw a very rare species up there while hiking that I've never seen before. Could these insects be trying to get away with the heat? Possibly. I have also heard reports of scorpion sightings in the Charleston area. Particularly the Hentz Striped Scorpion and the Striped Bark Scorpion. Which are native to Florida and parts of a few parts of southern Georgia. You also have to remember that the past few years we (Socastee, just south of Myrtle Beach) have never gotten below 20 degrees. I hope this year wont mess that streak up. I'm positive that some parts of Myrtle Beach are already 9a. I hope that I have a 9a microclimate myself. I've got a bright yellow south facing wall with black mulch beneath and a good amount of large bushes, anyone think it could be a very cold 9a or a very warm 8b? Personally, I highly doubt that Myrtle Beach wont become 9a in possibly even the next 10 years.

[kinzyjr]

47 minutes ago, Jimbean said:

I'd have to look at the numbers, but I find that hard to believe that it would be anywhere close to 10A there.  I can't imagine royals in London other than the family haha

Looks like more of a 9a or 8b over 30 years.  I'm sure the MET office has more complete numbers, but I'm not as familiar with how to use their site vs. NOAA and there is a lot of weeding to do today.

Here are the January minimums from 2010-2021 per TimeAndDate.com:

[Jimbean]

5 minutes ago, General Sylvester D. Palm said:

Wow! Wasn't expecting this post to blow up as much as it did! I have been noticing that the Common Conehead Katydids (a grasshopper like insect) have been slowly dwindling away. I am a insect and arachnid enthusiast and own the world's deadliest scorpion (Androctonus australis, Yellow Fat-tail Scorpion) along with 4 more various species of scorpions. Don't know why any of you would need to know that but every arachnid owner has to tell people about their weird addiction lol. Anyway, back onto subject, in the past years I have seen these Conehead Katydids pretty commonly. I have noticed in 2019 and 2020 they have started to disappear rapidly. This year I have only seen just a tad few. I took a trip up to Table Rock State Park near the very northwest of South Carolina (Zone 7b). When I was there I noticed far more Katydids than the past years, as if they have migrated. I also saw a very rare species up there while hiking that I've never seen before. Could these insects be trying to get away with the heat? Possibly. I have also heard reports of scorpion sightings in the Charleston area. Particularly the Hentz Striped Scorpion and the Striped Bark Scorpion. Which are native to Florida and parts of a few parts of southern Georgia. You also have to remember that the past few years we (Socastee, just south of Myrtle Beach) have never gotten below 20 degrees. I hope this year wont mess that streak up. I'm positive that some parts of Myrtle Beach are already 9a. I hope that I have a 9a microclimate myself. I've got a bright yellow south facing wall with black mulch beneath and a good amount of large bushes, anyone think it could be a very cold 9a or a very warm 8b? Personally, I highly doubt that Myrtle Beach wont become 9a in possibly even the next 10 years.

Remember what happened in Texas back in February 2021

[Silas_Sancona]

19 minutes ago, General Sylvester D. Palm said:

Wow! Wasn't expecting this post to blow up as much as it did! I have been noticing that the Common Conehead Katydids (a grasshopper like insect) have been slowly dwindling away. I am a insect and arachnid enthusiast and own the world's deadliest scorpion (Androctonus australis, Yellow Fat-tail Scorpion) along with 4 more various species of scorpions. Don't know why any of you would need to know that but every arachnid owner has to tell people about their weird addiction lol. Anyway, back onto subject, in the past years I have seen these Conehead Katydids pretty commonly. I have noticed in 2019 and 2020 they have started to disappear rapidly. This year I have only seen just a tad few. I took a trip up to Table Rock State Park near the very northwest of South Carolina (Zone 7b). When I was there I noticed far more Katydids than the past years, as if they have migrated. I also saw a very rare species up there while hiking that I've never seen before. Could these insects be trying to get away with the heat? Possibly. I have also heard reports of scorpion sightings in the Charleston area. Particularly the Hentz Striped Scorpion and the Striped Bark Scorpion. Which are native to Florida and parts of a few parts of southern Georgia. You also have to remember that the past few years we (Socastee, just south of Myrtle Beach) have never gotten below 20 degrees. I hope this year wont mess that streak up. I'm positive that some parts of Myrtle Beach are already 9a. I hope that I have a 9a microclimate myself. I've got a bright yellow south facing wall with black mulch beneath and a good amount of large bushes, anyone think it could be a very cold 9a or a very warm 8b? Personally, I highly doubt that Myrtle Beach wont become 9a in possibly even the next 10 years.

Neat.. Not the hugest fan of them, but, as with keeping Reptiles / Amphibians ( not keeping any personally atm ) do admire people who keep Arachnids / interesting Insects.. Out of curiosity, You keep any Tarantula sp. or Centipedes?

Your Katydid observations may be a clue.. same w/ the Scorps. though i know they can get around pretty easily.  What will be the big tell is if either sp. settles in and starts spreading around to more areas w/ out the aide of human- created micro climates that might help them survive harsh winters. 

Same w/ the much discussed recent arrival of the  Joro Spider, Trichonephila clavata which had established itself in N. Georgia not too long ago..   Had seen a few reports suggesting they likely wouldn't spread much ..but have my doubts, big doubts about those assumptions.    Me myself? would anticipate them to spread anywhere that is suitable over the next 10-15++ or so years.. Look what has occurred with the Brown Widow after it started moving around. Wouldn't mind them ( or near- related  Golden Silk Spiders ) in my own yard, imo.  Brown Widows have already arrived  .

As far as the Katydids, as mentioned, you may be seeing the suggested " retreat to higher / cooler places "  shift..  Have been hearing of similar observations regarding different critters from around AZ / CA. while the numbers of more " tropical / warm winter " insect sp. from just south of the U.S. / Mexico border -which might have been considered rare strays / seasonally migrant, or simply accidental observations previously-,  grow in the # of observations made, year to year..

Obviously, at least here, ( no doubt elsewhere too ) drought episodes will influence how things shift around ..but, imo, that might actually accelerate the process of retreat by anything that prefers cooler ( winters esp. ) over sizzling hot.

As far as anyone who might sight those " one - off"  winters to raise doubt  about an otherwise, overall steady trend upwards,  I'll say this ..Do a lengthy search of critters that like it warm / could be considered " tropical " on iNat,  across Central, and/ or S. Texas..  Been doing this myself all year since the freeze there..  While brutal on people and non native / some native plants of course, last winter's polar plunge doesn't seem to have disrupted the current distribution of things like Green Jays, Giant Cicadas, or various Butterfly sp. that have been expanding north out of Mexico in recent decades..  Chilly period might have sent some things headed back south for a month or two / knocked back some level of population a bit,  but, as cold as it was,  doesn't seem to have really wiped away any gains made..

All in all, the " Take four steps ahead / take one step back, every so often along the way " seems pretty typical in a shifting climate.. Never once have i heard that a warming world means it will suddenly no longer get cold  -ever- ..  Complete waste of time / energy / mind space worrying those rare cold winters anyway.. Stuff happens.. Plant again.

 

[UK_Palms]

2 hours ago, Jimbean said:

I'd have to look at the numbers, but I find that hard to believe that it would be anywhere close to 10A there.  I can't imagine royals in London other than the family haha

I suppose it depends on how you assess it. I thought hardiness zones were specifically based on minimum temperatures, which would make most of London 9a/9b. I mean NYC has hotter summers than London, generally speaking, but they are only 7B I think because they are much colder in winter. London isn't necessarily warm, it just lacks any serious cold compared to other places that are much closer to the equator, which seems to help a lot of the Mediterranean stuff survive here. Desert stuff as well, given the relatively low precipitation totals.

Average January highs in the warmest parts are only around 9C / 48F and average lows around 4C / 38F. Then in July average highs are only around 24C / 75F and lows are about 14C / 57F in the warmest spots. So it isn't overly warm in London. I think the term 'mild' sums it up pretty well. Those temperatures obviously aren't conducive with the survival of tropical stuff like Royals or Coconuts. And once a decade or so, even the mildest parts of London still drop down to about -5C / 22F. I don't think those parts have seen anything colder than -6C / 20F since 1987 though.

Heathrow is located in the inland western suburbs and is typically the warmest spot in summer, but it is often one of the colder spots in winter making it 9a. You won't see many big CIDP's or washies out that way, although I do know of a few. Likewise, east London is one of the cooler spots in summer, sometimes 3-4C colder than Heathrow and west London, but then it is also the mildest spot in winter due to it being closer to the coast and Thames estuary. That area is the potential 10a spot if we are only basing the assessment on winter minima. 

There are a lot of big washingtonia's in east London as well as Bougainvillea like the one I posted above. Filifera seems to do very well in East London since the rainfall totals are around 18 inches, compared to 25 inches in west London. There is probably about 4-5 different microclimates within the London metropolitan area, ranging from 8b in the northwest suburbs, to 10a along the Thames in east central London. Maybe the Thames gives off quite a bit of heat during the winter, from all the bath water flooding into it lol. The other night Northolt in northwest London went down to -1C / 30F while St James Park in central London only went down to 4C / 40F, a difference of 5C / 10F. So London clearly has quite a few microclimates.

[Pee Dee Palms]

8 hours ago, Jimbean said:

Remember what happened in Texas back in February 2021

Yes, but you can't base an entire hardiness zone on one freak cold snap. Again, remember the definition of a hardiness zone. The map is based on an average annual minimum temperature. Keyword is AVERAGE.

[kinzyjr]

20 hours ago, UK_Palms said:

I suppose it depends on how you assess it. I thought hardiness zones were specifically based on minimum temperatures, which would make most of London 9a/9b.

Certainly true.  A similar chart for Greenwich, this time with the months of Feb, Mar, Nov, and Dec included:

https://www.timeanddate.com/weather/uk/greenwich-city/historic?month=1&year=2020

[UK_Palms]

19 minutes ago, kinzyjr said:

Certainly true.  A similar chart for Greenwich, this time with the months of Feb, Mar, Nov, and Dec included:

https://www.timeanddate.com/weather/uk/greenwich-city/historic?month=1&year=2020

I find it hard to believe that Greenwich would go down to 16F in 2018, which is almost certainly during the February 'Beast from the East' event, when I myself saw a low of 12F here 35 miles inland and out in the rural countryside with no UHI. Greenwich would have been more than 4F warmer than my location. More like 8-10F warmer, given its proximity to the Thames estuary and the coast, as well as being within London's mammoth UHI. I doubt they dropped below 20F there in 2018. They could have, but I doubt it.

On the flip side the 2010 figure seems higher than it should be as well at 21F. December 2010 was actually the coldest month on record for London, or at least since the 1800's, yet the low is only 21F for 2010 compared to 16F in 2018, supposedly. There is no way the 2010 low was 5F warmer than 2018. Like if 2010 was listed as 16F for the low and then 2018 was only 21F, I wouldn't even question it. Again it could be correct, but it does seem 'off' to me. It's like the minima temps for those two years are the wrong way round.

Also, have you checked the stats for London City Airport on wunderground? That is the default station for London and it is within the supposed 10a zone in east central London and right along the Thames. Two of the past 3 winters haven't dropped below 35F, however last winter went down to 26F there I think. This backyard Robusta is also in east central London and isn't that far from London City Airport or Greenwich. I believe this photo was taken in fall 2018. Surely it wouldn't be looking like that after a low of 16F all the way up at 51N. The lower fronds look fine. 

 

Here is a Robusta in Ashburnham Grove which is actually in Greenwich. Street view is from April 2021. Do you reckon that thing would have seen 16F there in 2018? Looking back it didn't defoliate or anything on street view. Maybe a little tatty and windburned. Don't Robusta's burn below 23F and defoliate at 18F? Again this is in Greenwich where it says they had 16F in 2018.

. 

 

The Earl's Court Robusta in central London doesn't look like it was affected as I have seen quite a few 2018-2020 pics of it. This is from summer 2019, so it would probably still be recovering from a low of 16F up at 51N. I seriously doubt it has seen anywhere near that cold. More like 21-22F. 

 

Here are the Kew/Richmond Robusta's in May 2018, just after the coldest winter in the series with the supposed 16F during the BFTE. Wouldn't Robusta take more damage, this far north?

 

Here they are now, 3 years later...

 

I doubt any of these Robusta's would have seen colder than 21-22F over the past decade, even in 2018. Otherwise there would surely be more damage and delayed growth / set backs in 2019 as well. Especially this far north where summer heat and recovery capabilities obviously aren't as good. Yet they seem to be growing like rockets though over the past few years. They're probably another decade away from becoming London 'skydusters'. If only the local councils planted some on the streets that are already a decent size. They are a good gage of how cold it gets in a lot of places, since stuff like CIDP, Butia, Jubaea, Filifera etc won't burn until much lower, so it is harder to gage what temps they would have experienced during winter.

I think the consensus is that Robusta's burn at 23F and defoliate at 18F? Possibly higher at this northern latitude where cold is more prolonged and sunlight levels far lower in winter? So I doubt they have seen anything below the low 20s F, or they would surely be more damaged? I think most of central and eastern London is certainly 9b nowadays. The mammoth UHI being the primary factor in that, as well as some pretty notable climate change. Mind you the first proper taste of winter has just arrived here. 10 days of below average temps to come. Nothing below 35F for central and eastern London though. I wonder whether this winter will be much of a test for them? Probably another 9b winter for those Robusta's. I think everywhere in London has moved up a hardiness zone over the past 15-20 years or so. The current 9b was only 9a a decade or two ago.

[Jimbean]

Those look like hybrids

[UK_Palms]

2 hours ago, Jimbean said:

Those look like hybrids

If they are hybridised, they are still incredibly Robusta dominant. Bear in mind that a lot of these haven't lost their leaf boots yet or been shaved down. It will become more apparent how Robusta they are in the coming years as the trunks really start to elongate. The 40 foot Earls Court one is definitely pure Robusta or like 95% going by some of the trunk photos. I mean its trunk is rail thin and curves at an angle. I think the others will look thinner trunked too as they keep going upwards in the coming years and lose their lower leaf boots, but I guess we'll see. I may be wrong.

What is generally the minimum zonal requirement for Robusta? like 9a? Maybe 9b in a cool-wet winter climate? London isn't exactly ideal for Robusta's or washies in general, but they aren't doing too bad there at 51N. Any idea what the cut off point for Robusta's is on the west coast of the USA? Like the north Oregon coast? Southern Washington? I assume Robusta's will grow at Gold Beach, Oregon at lat 42N? Are there many Robusta pictures from Gold Beach? That is technically 9b I think, so central London is surely at least 9b as well by that merit. Although It's hard to make an argument for a 10a zone in London when you overlap the European and North American continents at the same latitude. 

 

Edited November 23, 2021 by UK_Palms

[Jimbean]

21 minutes ago, UK_Palms said:

If they are hybridised, they are still incredibly Robusta dominant. Bear in mind that a lot of these haven't lost their leaf boots yet or been shaved down. It will become more apparent how Robusta they are in the coming years as the trunks really start to elongate. The 40 foot Earls Court one is definitely pure Robusta or like 95% going by some of the trunk photos. I mean its trunk is rail thin and curves at an angle. I think the others will look thinner trunked too as they keep going upwards in the coming years and lose their lower leaf boots, but I guess we'll see. I may be wrong.

What is generally the minimum zonal requirement for Robusta? like 9a? Maybe 9b in a cool-wet winter climate? London isn't exactly ideal for Robusta's or washies in general, but they aren't doing too bad there at 51N. Any idea what the cut off point for Robusta's is on the west coast of the USA? Like the north Oregon coast? Southern Washington? I assume Robusta's will grow at Gold Beach, Oregon at lat 42N? Are there many Robusta pictures from Gold Beach? That is technically 9b I think, so central London is surely at least 9b as well by that merit. Although It's hard to make an argument for a 10a zone in London when you overlap the European and North American continents at the same latitude. 

 

I want to say 9A for robusta

[kinzyjr]

4 hours ago, UK_Palms said:

Also, have you checked the stats for London City Airport on wunderground? That is the default station for London and it is within the supposed 10a zone in east central London and right along the Thames.

There was almost 25 years of data on WUnderground.com: https://www.wunderground.com/history/monthly/gb/london/EGLC/date/2021-1

EGLC.xlsx

[UK_Palms]

@kinzyjr Thanks for abstracting and posting the data as I wouldn't have known how to do it myself. Great job and you have nailed the presentation of it in that table. An average annual minima of 26.69F would make that spot a 9b zone, right? Based off those records from the past 25 years there, which is quite a lengthy period. That does give a pretty comprehensive look at the minimum temps each month and each winter. It seems the absolute lowest there was 19F in those 25 years. No real palm killing temps, or at least not for bigger specimens. It seems 2018 only went down to 23F, which is the threshold for Robusta's not burning I believe? CIDP's and Filifera's probably haven't even been tested in that area for at leat 25 years then really if the lowest is only 19F and most years it only goes down to 26-27F. Exceptionally mild for 51N and being 25-30 miles inland from the coastline. 

I think it's fair to say there probably isn't any 10a zones in London right now though, at least not yet anyway. With climate change and an ever-expanding UHI that may change further in the coming decades. I believe central London has moved from 9a to 9b over the past 20 years or so, with the suburbs going from 8b to 9a. There has been a notable shift. You can actually see the winters that didn't go below freezing in this table (Dec 2019, Jan 2020, Feb 2020) as well as (Dec 2013, Jan 2014, Feb 2014). Both winters had 34F as a minimum. So 2 out of the past 6 winters have not technically reached freezing there. I suspect that spot may have got a bit colder back during the 1987 freeze though. Possibly down to 17-18F back then. The UHI has increased since then though and combined with climate change it may prevent it getting that low again there. I suppose there are no guarantees though.

Edited November 23, 2021 by UK_Palms

[kinzyjr]

8 minutes ago, UK_Palms said:

Thanks for abstracting and posting the data as I wouldn't have known how to do it myself. An average annual minima of 26.69F would make that spot a 9b zone, right? Based off those records from the past 25 years there, which is quite a lengthy period. That does give a pretty comprehensive look at the minimum temps each month and each winter. It seems the absolute lowest there was 19F in those 25 years.

Yes, 26.69F would be between the 25-29.9 the USDA assigns to zone 9b.  We could split hairs and say that it isn't exactly 30 years of data, but given the stability of the climate over that amount of time, I can't see another 5 years dropping the average below 25F.  NOAA has some data for the London area and see what comes from that.  There are some zone 10a areas on the SW coast of Ireland, and I think some growers take advantage of the reliably cool and moderate climate to attempt things like Juania australis and Ceroxylon.  I know Howea forsteriana tends to hold up pretty well to cool, but not freezing cold climates.  Do you know of any growing in the area around the airport you suggested?

16 minutes ago, UK_Palms said:

I think it's fair to say there probably isn't any 10a zones in London right now though, at least not yet anyway. With climate change and an ever-expanding UHI that may change further in the coming decades. I believe central London has moved from 9a to 9b over the past 20 years or so, with the suburbs going from 8b to 9a. You can actually see the winters that didn't go below freezing in this table (Dec 2019, Jan 2020, Feb 2020) as well as (Dec 2013, Jan 2014, Feb 2014). Both winters had 34F as a minimum. So 2 out of the past 6 winters have not technically reached freezing there. I suspect that spot may have got a bit colder back during the 1987 freeze though. Possibly down to 17-18F back then. The UHI has increased since then though and combined with climate change it may prevent it getting that low again there. I suppose there are no guarantees though.

I wouldn't worry about Zone 10.  You can go outside 9 out of 10 days without sweating or passing out from dehydration.  There are times where Christmas and New Year's Day are in the high 80s here.

On 11/18/2021 at 8:49 PM, General Sylvester D. Palm said:

Seeing Myrtle Beach as 8b and Virginia Beach as 9a seems super unlikely this far into the future. Does anyone know if this is a reputable projected hardiness zone map?

This is basically someone's best guess as to what might happen in the future.  No one will know for sure and I doubt I'll be around to find out anyways.

[GottmitAlex]

Wait, wait. Ireland has a 10a zone? Pray tell. 

[kinzyjr]

11 minutes ago, GottmitAlex said:

Wait, wait. Ireland has a 10a zone? Pray tell. 

This is one of the maps that shows where it is supposed to be - at the edge of the peninsulas on the southwest corner of the island:

Here is another similar map:

And one more from Trebrown:

@UK_Palms

I attached a few sheets from the NOAA UK stations for you.  Don't know how accurate they are.

NOAA_Hampstead.xlsx NOAA_Heathrow.xlsx NOAA_West_Malling.xlsx NOAA_Wisley.xlsx

[UK_Palms]

@kinzyjr Thanks for posting those as it gives a general insight into trends and microclimate estimates/zones for different areas. One thing I notice is that 1964 has a low of 2F at Hampstead, yet Heathrow only dropped down to 19F, which is a difference of 17F between the two stations. They are 10 miles apart as the crow flies. Also Heathrow is further inland out in the western suburbs, so in theory should be colder than Hampstead which is in north central London. Unless one station had cloud cover on a particular night? I also notice that Heathrow went down to 9F in 1962 when Hampstead only went down to 18F. Again they aren't too far apart. It does seem a bit fishy. Maybe the data wasn't as accurate or reliable back then perhaps?

Either way looking at those stats there is a definite warming trend in London, especially post 1990. Hampstead hasn't dropped below 20F since 1991. That isn't anywhere near the warmest part of London either and is probably only 9a at best there. Same with Heathrow and Kew Gardens. Central and eastern London on the other hand is clearly 9b now, given that Robusta's don't really get damaged and there is 30 foot Bougainillea in full bloom. However we could just be overdue a big freeze here, since it hasn't dropped below 20F in central London for 30 years and it looks like we have to go back ot the 60's for single digits anywhere in London. It would be interesting to see another central London station to see how it compares with these ones and London City airport. Is there any chance you can get the data up for St James Park in central London as that is the traditional central London station that is used by the Met Office. Cheers. Also Kew Gardens is another major station as well that I wouldn't mind seeing. 

Here is Dave Brown's Robusta / hybrid on the outskirts of London in 8b/9a. He doesn't really benefit from any of London's UHI where he is and that washie has probably seen as low as 13-14F before. Possibly even 12F. It's been there for about 20 years and given its size now it would surely take single digits to knock it out at this point, if 13-14F didn't kill it in 2018. I suppose it could get to single digits again where he is, outside of the UHI. However I think central London will never drop below about 15F now due to the sheer extent of the UHI nowadays, combined with climate change. I don't think central London has really dropped below 20F since 1987. It would be interesting to see what St James Park's lowest temps are in the series...? Almost certainly warmer than the other stations. With Kew Garden's, I'm not sure whether that is 8b or 9a there. It won't be as warm as St James Park or London City Airport. 

 

A guy called Josh posted this photo of a Kentia at Regents Park in central London. I don't know how long it has been there for...? There may be more than one. 

 

This video appears to show a decent sized Kentia at Regent’s Park, central London. At least I think it is a Kentia, in which case it is bigger than the other I posted.

 

Edited November 23, 2021 by UK_Palms

[kinzyjr]

7 hours ago, UK_Palms said:

Maybe the data wasn't as accurate or reliable back then perhaps?

We've had instances with NOAA readings where there were 10F+ discrepancies.  The last one I can remember was an observation from the Tarpon Springs Water Plant.  The recorded temperature was in the 20s and the weather underground readings everywhere around it were in the low to mid-30s.  It's not out of the question that the reading may have been inaccurate. 

7 hours ago, UK_Palms said:

Is there any chance you can get the data up for St James Park in central London as that is the traditional central London station that is used by the Met Office. Cheers. Also Kew Gardens is another major station as well that I wouldn't mind seeing. 

There is a chance.  I'd like to grab the data for all of the MET stations.  If anyone can grab the raw data and post it, I can feed it into a database and run a few queries on it pretty easily.

7 hours ago, UK_Palms said:

A guy called Josh posted this photo of a Kentia at Regents Park in central London. I don't know how long it has been there for...? There may be more than one.

Both of the Kentia posted look great.  That's really the best coconut replacement for oceanic climates. 

[Foxpalms]

On 11/21/2021 at 3:22 PM, kinzyjr said:

Looks like more of a 9a or 8b over 30 years.  I'm sure the MET office has more complete numbers, but I'm not as familiar with how to use their site vs. NOAA and there is a lot of weeding to do today.

Here are the January minimums from 2010-2021 per TimeAndDate.com:

For me its showing For London city airport 2022 32f 2021 25f 2020 34f 2019 30f 2018 23f 2017 27f 2016 30f 2015 28f 2014 34f on wunderground which is an average of 29.2f  which sounds more accurate to me also bear in mind this is taken at the airport not in the city so on those 25f and 23f nights its probably about 2 or 3f higher in the city and areas surrounded by buildings in central London also because I doubt all kentia palms outside shops and restaurants  would still be alive especially in pots in Central London during 2018 and I know a lot of them were just left outside with no protection and survived which suggests the temperature was probably around 26f in 2018 in the non parks/airports areas.  So if at the airport its yearly average minimum low is 29.2f in the last 9  at the airport there is probably a good chance in the nearby city areas along the Thames and  around London city airport there is a small area of  zone 10a. London in the last 10 years or so has warmed up a bit and most of the data for averages is outdated in my opinion take for instance London Heathrow ( I cant find this data for central London but I will use Heathrow as an example)  Heathrow  has a daily high of about 0.3f warmer in the summer but at night its about 5f warmer in summer in central London and in the winter its also a lot warmer at night in central London and in the day its slightly warmer during winter in central London. Below is how the temperature has changed at Heathrow in the last 10 years.

[Foxpalms]

1 minute ago, Foxpalms said:

For me its showing For London city airport 2022 32f 2021 25f 2020 34f 2019 30f 2018 23f 2017 27f 2016 30f 2015 28f 2014 34f on wunderground which is an average of 29.2f  which sounds more accurate to me also bear in mind this is taken at the airport not in the city so on those 25f and 23f nights its probably about 2 or 3f higher in the city and areas surrounded by buildings in central London also because I doubt all kentia palms outside shops and restaurants  would still be alive especially in pots in Central London during 2018 and I know a lot of them were just left outside with no protection and survived which suggests the temperature was probably around 26f in 2018 in the non parks/airports areas.  So if at the airport its yearly average minimum low is 29.2f in the last 9  at the airport there is probably a good chance in the nearby city areas along the Thames and  around London city airport there is a small area of  zone 10a. London in the last 10 years or so has warmed up a bit and most of the data for averages is outdated in my opinion take for instance London Heathrow ( I cant find this data for central London but I will use Heathrow as an example)  Heathrow  has a daily high of about 0.3f warmer in the summer but at night its about 5f warmer in summer in central London and in the winter its also a lot warmer at night in central London and in the day its slightly warmer during winter in central London. Below is how the temperature has changed at Heathrow in the last 10 years.

This year is also on track to be above the outdated averages for London. We are by no means a hot 9b where I live or 10a in the area around London city airport that can grow royals foxtails ect but queens are doing fine for me and kentia palms and archontophoenix cunninghamiana are worth a try in central London and lots of other palms such as dypsis palms that can tolerate cool weather other than just dypsis decipiens and chamaedorea radicalis and mircospadix. A lot of things tried in the uk are either in the colder outskirts of London or even if tried in Cornwall their summers being cooler than Londons mean they cant grow a lot of palms because the don't have enough heat in their summer  for queens ect not much data on palms tried in central London other than the usual ones so I will have to do a lot of experimenting with palms . Here is the data for this year so far from London Heathrow if anyone can find the data for central London other than private weather stations that would be useful.

[Foxpalms]

45 minutes ago, Foxpalms said:

For me its showing For London city airport 2022 32f 2021 25f 2020 34f 2019 30f 2018 23f 2017 27f 2016 30f 2015 28f 2014 34f on wunderground which is an average of 29.2f  which sounds more accurate to me also bear in mind this is taken at the airport not in the city so on those 25f and 23f nights its probably about 2 or 3f higher in the city and areas surrounded by buildings in central London also because I doubt all kentia palms outside shops and restaurants  would still be alive especially in pots in Central London during 2018 and I know a lot of them were just left outside with no protection and survived which suggests the temperature was probably around 26f in 2018 in the non parks/airports areas.  So if at the airport its yearly average minimum low is 29.2f in the last 9  at the airport there is probably a good chance in the nearby city areas along the Thames and  around London city airport there is a small area of  zone 10a. London in the last 10 years or so it  has warmed up a bit the temperatures are milder than the 30 year data and I cant see it getting colder I find that London gets the coldest day of the year in Jan or Feb when the on clear nights when the wind is coming from scandanvia but as they recently have had warmer winters it means prolonged cold or very low temperatures is less and less likely these days there most of the data for averages is outdated in my opinion take for instance London Heathrow ( I cant find this data for central London but I will use Heathrow as an example)  Heathrow  has a daily high of about 0.3f warmer in the summer but at night its about 5f warmer in summer in central London and in the winter its also a lot warmer at night in central London and in the day its slightly warmer during winter in central London. Below is how the temperature has changed at Heathrow in the last 10 years.

 

[Foxpalms]

My point is London in the last 10 years or so it  has warmed up a bit the temperatures are milder than the 30 year data and I cant see it getting colder I find that London gets the coldest day of the year in Jan or Feb  on clear nights when the wind is coming from scandanvia but as they recently have had warmer winters no where near as much snow there in winter there recently  it means prolonged cold or very low temperatures are less and less likely these days and unless its going to get colder in the winter there  which is unlikely looking at the trend of warmer temps that  means it won't be as cold here for the lowest temperature so I can see the last 10 years or so being a better reference point for growing less hardy palms but there is still a risk with certain ones even if it's low these days. Personally I think zone 9b or 10a winters are much more likely for the years to come since when the coldest air of the years comes in the future the air brought from scandanvia will be less cold than it use to be but of course clouds or clear sky are what will probably determine if it's 9b cold or 10a cold and even with clear skies 9a cold in central London is not likely to come in the future if scandanvia and Northern Europe also have warmer winters 

Edited June 28, 2022 by Foxpalms

[SeanK]

Take these speculative maps with a grain of salt. The SE US typically sees approx 18 "normal" winters followed by two cold ones. For z8b Augusta GA, it means eighteen winters with a 17° average then a couple cold ones at 13°F.

[Aceraceae]

On 11/21/2021 at 1:02 AM, GottmitAlex said:

I think they should update the USDA hardiness zone map. 

I think we are still based on 2012.

The "2012" map uses 1975 to 2005 data, NOT 1981 to 2010, so it's quite outdated. Luckily there are new Köppen (using -3 C isotherm for Dfa/Cfa distinction) maps out, and so many homemade hardiness maps using the same mean minimums the real maps use anyway. 

Yes there's zone 10 in Western Europe. But it's a cool oceanic zone 10, just like a fridge is cold zone 10 and a house is a cool zone 13 or 14.