USDA Hardiness zone is not a good way to have a abstract view on minimum temperatures

[greekpalm]

USDA hardiness zone is calculated by the average annual minimum. I know that temperature is not the only factor that kills palms in the winter.... but lets take extract only the temperature factor.

I consider is a bad way to calculate someones minimum climatic temperature. let see the following example

year 1: -4C

year 2: 3C

year 3: 5C

year 4: 4C

year 5: 4C

so this would mean that the average annual minimum would be 2.4C or hardiness zone 10b

If someone plants a 10b palm would be fine for a couple of years until that one cold year will strike back (in our example -4C which would correspond to hardiness zone 8b) and the palm will fry!

As many palm lovers have seen the last years in Florida global warming wont save your palms, and a new better way to categorize average annual minimum temperatures should be used.

A factor we have to take into account is :

1) the amplitude of the deviation of the absolute minimum with the average annual minimum

and

2) in a lesser extent the deviation and frequency of all the annual minimum temperatures compared to the average annual minimum (all negative fluctuations)

as a result we will obtain a more reliable view on what we can and cannot plant in longterm.

i hope anyone has anything to say about this

(bear in mind that i'm not talking about other factors that kill palms in the winter but ONLY about minimum temperatures)

[WestCoastGal]

The USDA hardiness zones are helpful only to a certain extent for many of the reasons you pointed out above. And a plant's healthiness is also determined by hours of daylight and moisture for example. I drove myself crazy trying to gather info on what could and couldn't grow well in my area. I'm looking for low maintenance but a lush green landscaping all the same. I really don't want to go to the efforts that so many valiant palm growers do go to. We're just doing our landscaping now and the thought of removing and replacing a mature palm can be challenging and costly in a small lot especially when surrounding structures and hardscape play into it. I found I had to go to all different reference books for info to come up with a potential list of what I liked. Even in our area since it is comprised of mountains and valleys, there are microclimates that come into play. I do think the way that Sunset Magazine (a California West Coast publication) breaks down zones and subzones is helpful. Here's a link to Sunset Garden's Climate Zones if your interested although it only covers the U.S. Do you have something similar in Europe to this?

Edited December 30, 2010 by WestCoastGal

[QUINNPALMS]

microclimates are key!!

[happ]

I am not sure of the length of years involved in determining USDA zones. Probably the data is close to 100 years of records for a general area. So the calculation of "average" coldest minimum temperatures is solely a mathematic figure. How the zones are identified across geographic areas is much more difficult considering not only variations in minimum temperatures over a large areas [states] but also unique features that create micro-climates.

USDA zones are merely a measurement of average coldest minimums; nothing more. As we know, there are zones that include very cool climates [i.e. San Francisco] where minimums below freezing, the temperature where water becomes a solid [ice] is quite rare. Within the same zone [uSDA 10] are cities that observe very warm year-round temperatures [i.e. Orlando] but may be more prone to sub-freezing episodes. Conceivably a species of palm common to the subtropics [i.e. roystonea regia] could survive in San Francisco at 38N latitude since it is in the same USDA zone as central Florida but it would not thrive. The hardiness of a particular palm must include more factors than just coldest minimum temperatures. At 28N latitude [Orlando] royal palms may thrive but then succumb to the rare but more frequent episode of freezing temperatures.

[Xenon]

The 1990 USDA map is only based on 12 years of data(1974-1986) which included the 83 and 85 freezes, so zone 10 areas of deep south Texas and coastal central Florida were pushed southward....

Coconuts seem to make if for a while in Corpus Christi, Texas and Daytona Beach, Florida, which according to the map are both within USDA zone 9a. The Arbor Day Map seems to be more accurate IMO, except there aren't any half zones.

Just my 2 cents,

Jonathan

Edited December 30, 2010 by Xenon

[Takil-Explorer]

Well in the end iots not your average winterlow in a normal winter but the odd cold winter wich will do the damage. What survives the lowest extremes in your area or garden you can plant savely. And cold winter can hit randomely, every winter there is a chance you get that coldsnap.

After the very cold winter of 1979 I had seen that 2 species of palm did survive, a Chamaerops in a garden here in town and a Trachycarpus fortunei. In my town it had been -17 that winter. So that made me realise that there are some palms wich can be grown in our climate here. And microclimate is the other thing. My Chamaerops was planted at the warmest spot where the snow always started to melt. Well thats was at my old place. I consider my zone a zone 7. And microclimate an 8.

When people say in the Netherlands they have a zone 9 climate they make a mistake. A cold winter will teach them that. Well I always tell people that only a few palms are realy reliable hardy here. A lot of the younger generation had never seen cold winter, and where believing that they are something of the past.

Alexander

[_Rich]

I've got moderately comprehensive Excel spreadsheet (270 species) compiled by Larry R. Noblick from Montgomery Botanical Center and Fairchild that denotes varying survivability stages in temperature (degrees Fahrenheit)by species. If anyone is interested in this, please shoot me a PM with your email.

Rich

[greekpalm]

USDA zones are merely a measurement of average coldest minimums; nothing more. As we know, there are zones that include very cool climates [i.e. San Francisco] where minimums below freezing, the temperature where water becomes a solid [ice] is quite rare. Within the same zone [uSDA 10] are cities that observe very warm year-round temperatures [i.e. Orlando] but may be more prone to sub-freezing episodes. Conceivably a species of palm common to the subtropics [i.e. roystonea regia] could survive in San Francisco at 38N latitude since it is in the same USDA zone as central Florida but it would not thrive. The hardiness of a particular palm must include more factors than just coldest minimum temperatures. At 28N latitude [Orlando] royal palms may thrive but then succumb to the rare but more frequent episode of freezing temperatures.

thats exacly what i want to explain in the case of Orlando which shouldnt be considered zone 10,,, due to the fact that once every X years a big freese occurs and all that hard labour of the past 10 years is forzen

as i said before i'm not talking about rainfall or seasonal paterns or mean temperatures or max temperatures or whatever .. im talking purly about annual minimum temperatures.

you can see the example i gave above... that a zone 10b (due the averaging) can have a winter minimum of zone 8b...

[Erik]

As with westcoastgal, I agree that the Sunset system packs in a lot more information.

And as with Jonathon, I use the arborday zone maps. I don't mind giving up the half zones as I think they give a false sense of security.

By the USDA system, I'm zone 6b; I'm zone 7 by the arborday method.

But I have to realize that eventually I'll have a winter low of -20 oC or so as that happens about once a decade. Hence, I am prepared to offer electric heat to all palms other than the needles if it comes to that.

Alexander, you are of course right about microclimates. However, I chose to plants my palms in the worst possible microclimate so I protect them in winter more than I "ought" to have to do here.

==Erik

P.S. have to add: low of +14 oC today; high of +20 oC expected! Got to love OK weather.

[gsytch]

I live by a simple rule - if its been THAT cold in the past 50 years, that is my zone. While I am officially in zone 9b, it has hit 19f in Tampa. I cannot go back and see New Port Richey because there are no official temps for me, so I defer to Tarpon Springs. In that event, Tampa's temp was not taken on a warm runway near the water, hence why today we dont see those temps when locations a few miles away are bitterly cold. While they were waiting for ice to melt on planes at TIA, they said the low was 32f which would never cause that much ice. However, 6 miles away it was 26f, probably the truer low. I usually carry within a degree of Larry in Tarpon, who is 9 mi south of me. It did hit 27f in 2003 in my open yard, and in 1996 it also hit 27f there. BUt, both those were pre-hurricane years (Hurricane Jeanne took down my 3 big trees INTo my house) and temps under the trees were 3f warmer. I have since regrown some canopy, and I can SEE the difference. So, I consider myself 9b. I plant 9b stuff. If I plant 10a stuff, I enjoy it until it freezes. If I plant 9a stuff, I do so in OPEN, EXPOSED areas never to worry. Now, back to those 10a winters would be nice!

[yachtingone]

I like to think I live in zone 9b. Thats right 95% of the time! The 5% of the time is far from 9b though! It gets as cold as 24f. sustained for over 24 hours and 110f. day time high sustained for 9 days.

I am not sure what zone that puts me in? It states I have a death camp for some of my plants when I get a hard frost! I have very few plants that can't handle bellow 26f.

Randy

[happ]

I like to think I live in zone 9b. Thats right 95% of the time! The 5% of the time is far from 9b though! It gets as cold as 24f. sustained for over 24 hours and 110f. day time high sustained for 9 days.

I am not sure what zone that puts me in? It states I have a death camp for some of my plants when I get a hard frost! I have very few plants that can't handle bellow 26f.

Randy

Not sure I understand the "24f sustained for over 24 hours" You don't mean that the temperature remained 24F all day and night for 24 hours, right?

[Jimbean]

My map is the best one that I know of regarding Florida.

[yachtingone]

I like to think I live in zone 9b. Thats right 95% of the time! The 5% of the time is far from 9b though! It gets as cold as 24f. sustained for over 24 hours and 110f. day time high sustained for 9 days.

I am not sure what zone that puts me in? It states I have a death camp for some of my plants when I get a hard frost! I have very few plants that can't handle bellow 26f.

Randy

Not sure I understand the "24f sustained for over 24 hours" You don't mean that the temperature remained 24F all day and night for 24 hours, right?

No I said that wrong Happ. Two nights in a row we got down to 24f. daytime was probably bellow freezing. The sun couldn't melt ice inbetween the two cold 2007 nights

Randy

[greekpalm]

My map is the best one that I know of regarding Florida.

lets take Daytona beach as an example... its situated in zone 9B. So by this map you can plant king palms or royals over there...

but the record low in Daytona is 15F ! that would almost surely kill all those palms... (btw 15F is zone 8A thats a 1.5 zone difference)

and 15F might be a record low but 20F isn't ...

another example is .. tampa . Tampa is in zone 10A

but it had a record low of 18F !! thats zone 8B !!! your palms would be dead .......

guys those temperatures do occur once in a while (more then you might think) thats why i would like to make a new map based on the details provided in my first post on this thread.

[Xenon]

I think subtropical areas are less stable temperature wise then Mediterranean climates. If the USDA map was based off record lows, I'd be in zone 7b and probably less then 1% of Texas would make zone 9a. Miami would be in zone 9b.... Why worry about record lows(it's like a 50 year occurrence)...when you can enjoy what's now. Just replant, or move to Hawaii.....

Jonathan

Edited December 30, 2010 by Xenon

[Jimbean]

My map is the best one that I know of regarding Florida.

lets take Daytona beach as an example... its situated in zone 9B. So by this map you can plant king palms or royals over there...

but the record low in Daytona is 15F ! that would almost surely kill all those palms... (btw 15F is zone 8A thats a 1.5 zone difference)

and 15F might be a record low but 20F isn't ...

another example is .. tampa . Tampa is in zone 10A

but it had a record low of 18F !! thats zone 8B !!! your palms would be dead .......

guys those temperatures do occur once in a while (more then you might think) thats why i would like to make a new map based on the details provided in my first post on this thread.

subtropical climates are a bit different. Royal palms are not 9B palms, they are 10A palms. My map is based on a 50% chance of survival over the course of the life of the plant. So in coastal Brevard and St. Petersburg there is a 50% chance that a royal palms will survive long term.

I agree that using all time record lows is the most conservative way of deciding what you want to grow there. In that case, first consider that in a Mediterranean climate, cold events are longer lived than in subtropical climates (where most cold data is taken) and take that into consideration. Secondly, find out the coldest temperature in your area, and adjust for any microclimate that you might have, and give yourself a classification, (say, if you are 18F, than you could conservatively estimate yourself in 8B). 8B plants can take 15F with no damage, and die somewhere between 10F to 15F; 9A plants can take 20F with no damage, and may die somewhere between 15F and 20F; etc.

[Alan_Tampa]

Royals have held up pretty well the last few cold winters here in Tampa, anything with some size recovered quickly last summer. Also, I gave up with zones, I know that most of the time Tampa is good for many, many tropical plants. Its only the few (usually!) crappy events that cause trouble. With some effort and good luck one can maintain a garden (or patch of weeds like mine) that is fairly tropical.

Alan

[chris78]

I also think we must understand that the USDA zones really don't consider people growing tropicals palms in subtropical climates.. Most people in the USA are growing temperate plants in temperate climates. And thats a different animal altogether... Most temperate plants (trees and shrubs) just DIE BACK if it gets colder than it tolerates. Where I grew up, T-roses had no problem most winters but ever so often it got cold enought to freeze them back and sometimes freeze them to the ground. But they come back in spring budding from the lower stems or even regrewing from the roots.

Even some tropical plants do the same... In the cold winter of 2007 I loss all my zone 10 palms, only a few clumping species came back... On the other hand I did not loss any of my zone 10 flowering trees, yes the dies back and some to the ground but they recovered. My mangoes also come back from the lower trunk...

Most palms just don't die back, but just DIE when it gets colder than they can handle. So yes the USDA zones is not that good when growing palms in marginal climates. Thats why this site is good because we can talk about palm growing.. because palms are very different in many ways than growing woody plants.

Edited December 30, 2010 by chris78

[spockvr6]

Very well said chris78.

[bubba]

USDA Zone system analysis is an extremely poor measure for determining the viability of a tropical/subtropical Palm as well as most tropical vegetation.For example, a climate that remained a constant temperature of 40F would be classified Zone 11 USDA.Can a Coconut Palm grow in this climate? Of course not. That stated, Coconuts are regularly posted on this Board in Orlando (19 F)and Brownsville (12 F)that based upon all time minimum temperatures qualify as Zone 8 USDA.

The USDA is a flawed system that at best gives a very basic overview on climate. It does not take into consideration the variety of climate assessed. No distinction is made between Med., Desert or many other varieties that take into account accumulated heat as well as higher average temperatures.

The Koeppen Classification has always been a more accurate indicator for "what grows" in Florida.It's reliance on the average minimum temperature in the coldest month equaling 64F or higher as the commencement of the tropical designation seems to go hand in hand with the area where the coconut grows. The coconut is the leading index for your entry into the tropics.

[Xenon]

The lowest minimum for Brownsville for the past 100 years has been 16F set back in 1989. The normal lows(32-35F) however compensate for this and the 100 year minimum for Brownsville is 30.75(source). The lowest temperature in Brownsville for the last 20 years is only 28F. Wonder what the 100 year minimum for Orlando is, recent data seems identical to Brownsville's.

Jonathan

Edited December 31, 2010 by Xenon

[WestCoastGal]

Since Tampa, Fl was mentioned a few times I decided to plug in it's Sunset zone (26) into the Sunset Plant Finder Guide and check for palms/cycads that would be suited for that area.

Here's what came up for full sun, moderate water:

Brahea armata; Butia capitata; Chamaerops humilis; Cordyline australis 'Albertii'; Livistona; Livistona australis; Phoenix canariensis; Rhapidophyllum hystrix; Sabal, Sabal mexicana; Sabal minor; Sabal palmetto; Syagrus romanzoffianum; Trachycarpus fortunei; Washingtonia; Washingtonia filifera; and Washington robusta.

These plants sound more like USDA Zone 9a to me rather than a 9b or 10a.

Since Tampa and New Port Richey are in the north end of the zone they would fall into the area with lows from 15F, an 11-month growing season and periodic hard freezes. Below 20F would translate to an 8b I think on the USDA chart. It's funny because with Florida's hot summers I always think of it being a warmer area than it really is year round.

[Xenon]

Since Tampa, Fl was mentioned a few times I decided to plug in it's Sunset zone (26) into the Sunset Plant Finder Guide and check for palms/cycads that would be suited for that area.

Here's what came up for full sun, moderate water:

Brahea armata; Butia capitata; Chamaerops humilis; Cordyline australis 'Albertii'; Livistona; Livistona australis; Phoenix canariensis; Rhapidophyllum hystrix; Sabal, Sabal mexicana; Sabal minor; Sabal palmetto; Syagrus romanzoffianum; Trachycarpus fortunei; Washingtonia; Washingtonia filifera; and Washington robusta.

These plants sound more like USDA Zone 9a to me rather than a 9b or 10a.

Since Tampa and New Port Richey are in the north end of the zone they would fall into the area with lows from 15F, an 11-month growing season and periodic hard freezes. Below 20F would translate to an 8b I think on the USDA chart. It's funny because with Florida's hot summers I always think of it being a warmer area than it really is year round.

, when I put in Brownsville, Texas' sunset zone(27, Rio Grande Valley), Caryota, Ptychosperma, Dypsis and Roystonea(even Hedyscepe and Jubea!) come up. I'm sure there are places in Central/Inland Florida(zone 26) that are as warm and warmer then Brownsville. Tampa's record low is only 18F and that's very rare...definitely not zone 8b.

I don't think any map is gonna tell you what you can and cannot grow....

Just my 2 cents,

Jonathan

Edited December 31, 2010 by Xenon

[_Keith]

I have a much more simplistic view. It takes 12 to 20 years or more of weather to establish a climatic zone. It takes one cold night to kill a palm.

If you want to know what grows in your neighborhood long term, just take a quick inventory of palms in the area that are 20 to 30 years old. Those are safe. Anything else is an experiment at best. Want to experiment, go ahead, so what. Your most expensive out of zone palm will probably cost a tenth of what your car cost, and odds are it won't make a decade, probably half that.

Plant it, enjoy it, but understand it's dispensable.

[gsytch]

Heat Island Effect needs to considered, too. I believe that is why some locales will never touch those record lows, such as Tampa and St Pete. You can see, on a cold, clear winter night, temps dropping in the suburbs while more slowly in the city. Newark,NJ is a perfect example. Despite being way up N in NJ, it is usually the warm spot. I grew up 30 mins S of Newark, in Edison, and our climate was heavily influenced by being within a few miles of Raritan Bay and the northern Jersey shore. While I didn't know that much about weather, I was always planting my veggie garden in late April and never suffered losses, a full 3 weeks earlier than should. Mom, too. That is another microclimate. That said, one of my good friends lives only 3 miles east of me here, and his lows this past week were 22f and 23f, consistent with Wesley Chapel's reporting station (25 mi east). We've known each other for 15 years, living in the same houses, and I've been there after a freeze event only to jaw drop at the damage. Then I return to my house and see only more superficial damage. New Port Richey is not a big city, but a city nonetheless and near the Gulf. This past freeze has toasted the yard but far from kill. My big Triangle out front, over 30' tall, is still growing! Fingers crossed. lol

[bubba]

Xenon, The lowest temperature ever recorded in Brownsville, Texas was 12F. during the horrible Feb.12-14 freeze of 1899. Richard Travis has written an outstanding history of the Texas freezes that are easily assessible on the on the South Texas Palm Site. There is no doubt that South Texas has fared extremely well in recent times. That stated,the long term historical data cannot be ignored. As it has been stated, all that lies between Texas and the Artic is barb wire fence. This can amplified when you consider that Tampico, Mexico, which is below the Tropic of Cancer, has recorded lows well below freezing.

Palmerati did an outstanding topic on Palmtalk, that I cannot locate, that detailed historical freeze events in both Florida and Texas.In Florida, the devastation of the three 1983,1985 and 1989 freezes are hard to forget but they paled when compared to the freezes of 1893,1894 and 1899.Numerous others have transpired before and after the 1890 freezes in Florida detailed in Palmerati's Post.Generally, Florida's freezes are less severe compared to South Texas because Florida is moderated to some degree by the surrounding water,lakes and the Gulfstream.As I write this, it certainly takes a hollow ring given our Dec./2010 not to mention our Jan./2010.

Californians are certainly not immune.While freezes as recent as 2007 are still felt, one only needs to look back historically to the freeze events of 1949,1937 and 1912 to obtain a perspective on what is possible.

Freezes are an inevitable part of our climate and are particularly cruel to those of us pushing the envelope with tropical Palms.Unfortunately, just as we acclimate to a warm phase, time after time we are brought back to earth by an 1899 episode.I think the best attitude is to continue to push the envelope but recognize humbling reality is around the corner.It is not the end of the world. Replant and keep trucking.

[Xenon]

Xenon, The lowest temperature ever recorded in Brownsville, Texas was 12F. during the horrible Feb.12-14 freeze of 1899. Richard Travis has written an outstanding history of the Texas freezes that are easily assessible on the on the South Texas Palm Site. There is no doubt that South Texas has fared extremely well in recent times. That stated,the long term historical data cannot be ignored. As it has been stated, all that lies between Texas and the Artic is barb wire fence. This can amplified when you consider that Tampico, Mexico, which is below the Tropic of Cancer, has recorded lows well below freezing.

Palmerati did an outstanding topic on Palmtalk, that I cannot locate, that detailed historical freeze events in both Florida and Texas.In Florida, the devastation of the three 1983,1985 and 1989 freezes are hard to forget but they paled when compared to the freezes of 1893,1894 and 1899.Numerous others have transpired before and after the 1890 freezes in Florida detailed in Palmerati's Post.Generally, Florida's freezes are less severe compared to South Texas because Florida is moderated to some degree by the surrounding water,lakes and the Gulfstream.As I write this, it certainly takes a hollow ring given our Dec./2010 not to mention our Jan./2010.

Californians are certainly not immune.While freezes as recent as 2007 are still felt, one only needs to look back historically to the freeze events of 1949,1937 and 1912 to obtain a perspective on what is possible.

Freezes are an inevitable part of our climate and are particularly cruel to those of us pushing the envelope with tropical Palms.Unfortunately, just as we acclimate to a warm phase, time after time we are brought back to earth by an 1899 episode.I think the best attitude is to continue to push the envelope but recognize humbling reality is around the corner.It is not the end of the world. Replant and keep trucking.

I believe this is the thread you're referring to, Bubba? Loaded with info...

Looking Back at the Great U.S. Freezes

Jonathan

[Takil-Explorer]

Maybe you should make more use microclimates! As I live in a much coldere climate I know that microclimates are the key to succes! And I focus on stuff wich is reliable rathr then growing stuff wich is to tender. In the UK and Ireland lots of people where growing so cold coldhardy palms and treeferns. Well probably a lot of them will not be that coldhardy. And lots of people get a wrong idear of what they can grow from that USDA zone system. Especially those new in growing exotic plants. They buy optimisticly a lot of expensive palms and then after a hard winter like the current ones they will be very dissapointed. I have seen several sad cases of these arround here!

Alexander

[bubba]

Xenon, Thank you for locating Palmerati's topic. I think I was a little more argumentative at that time.Time to give it up!

[sonoranfans]

1) The mean minimum temp is not terribly reliable in determining your low over the lifetime of the palm

2) the record minimum is not likely to repeat in the lifetime of the palm, so its extreme in the pessimistic direction, unless you can never have a palm die of cold again in your life.

3) The duration of the cold matters as much or more than the minimum for many palms.

4) frost has the power to kill palms at higher temps than dry air because it takes heat out of the palm faster than just cold air.

5) If the death of the palm occurs from freezing of the sap and bursting of plant cells, its the temperature of the palm that matters, not the temperature of the air, hence the duration of cold. Big thick trunked palms will take many hours for the center of the trunk to get close to the air temperature because cellulose is an insulator.

No system is perfect, and the one saying Brahea armata and Washingtonia Filifera were good choices for Tampa is just dumb, as these palms wont be healthy here in the higher moisture than their natural environs. they likely wont survive to the same temps as they would if they were healthy.

Mediterranean climates and desert climates will have smaller deviations from the mean minimum temperature because moisture drives cooler winter weather and those areas will also be more heat island dominated because they are dominated by radiative cooling events. In florida, it seems the temnperature deviations are just crazy. the averave january minimum in my area is about 53F, but we have seen sub 30 twice in december, and 27F(?) last january. Last january was 26 degrees below the average minimum. In my ten years in phoenix arizona, I saw a 30 year low(21F) and the average was 32F for that time of year, an 11F difference. If phoenix were to drop to 26F below th average minimum, it would be 6F, and the record of 16F in the late 50's(?) is not likely to be seen ever again because the heat island effect has caused the average minimum january low to rise 5F in phoenix.

So no system is perfect, and in my area of florida with its huge variance in winter minimum temps, I just have to decide how I will play the statistics. I am not going to give up and totally limit myself, but I will grow canopy to protect against frost and radiative cooling events that kill tender palms. The canopy trees will be robust and enable me to grow a modest fraction of zone 10a/b palms perhaps close to the house to facillitate the microclimate. I wont just give up when palms die because I have no canopy. Its time to grow the canopy, I've seen it work wonders, so I will be ensuring that my use of canopy creates microclimates where I can have a few, or perhaps a dozen zone 10 palms.

[abirdsoars]

Hey everyone -- This thread is a little outdated, however maybe we can bring it back to life!?

I am new to this whole forum thing but I am loving seeing so many other people with the same interests as me.

I recently came across this fresh version of the Plant Hardiness Zone Map & think it will be beneficial to all gardeners.

https://gilmour.com/planting-zones-hardiness-map

I truly hope you all get a chance to check it out and enjoy it as much as I do!!

 

[GottmitAlex]

6 hours ago, abirdsoars said:

Hey everyone -- This thread is a little outdated, however maybe we can bring it back to life!?

I am new to this whole forum thing but I am loving seeing so many other people with the same interests as me.

I recently came across this fresh version of the Plant Hardiness Zone Map & think it will be beneficial to all gardeners.

https://gilmour.com/planting-zones-hardiness-map

I truly hope you all get a chance to check it out and enjoy it as much as I do!!

 

Thank you. Now I know I am in a 10b plant zone.

Edited April 24, 2018 by GottmitAlex

[RedRabbit]

If only the business of prediction were easy... 

Going off the average annual low has problems because it of outlier events like others have pointed out. Even going off record lows isn't perfect either; how many records fell before the current one was established? 

 

[Xerarch]

I wonder do you really want to plan your garden on the absolute record anyway? You might leave off wonderful plants that you could enjoy for decades and have nothing happen to it. I’m willing to take some moderate risks and have some things I really enjoy. 

[Alan_Tampa]

10 hours ago, Xerarch said:

I wonder do you really want to plan your garden on the absolute record anyway? You might leave off wonderful plants that you could enjoy for decades and have nothing happen to it. I’m willing to take some moderate risks and have some things I really enjoy. 

I plant whatever I think has a snowballs chance. Some stuff with less than that. The result: some cool stuff, sometimes big piles of dead sticks. It's fun either way. 

[kinzyjr]

My philosophy is to keep a few benchmarks in mind.

My first, and most conservative, is our record low of 20Fset in1962 and matched in 1985.  The bulk of my plants could survive that including 2 x rhapidophyllum histrix, 3 x sabal minor 'bluestem', chamaerops humilis 'cerifera', clumps of rhapis excelsa, 4 x phoenix dactylifera, 25 x sabal palmetto, and 30 x phoenix theophrasti.  Even if I lose everything else, I still have something rather than a complete kill. 

My second benchmark is January of 2010, with 3 nights in the 20s and an ultimate low of 26F.  My phoenix roebelenii would likely squeak through, and didn't take any damage from this January's repeated cold blows.  My bismarckia nobilis wouldn't like it, but would probably live since the one on Lake Hollingsworth made it.

Then there are the plants that require yearly protection like my various cocos nucifera.

Additionally, as @sonoranfans mentioned, you can use siting, canopy, and windbreaks to give yourself an edge.  The rest of the plants on my property are relatively hardy trees, like live oaks, and hedges, like podocarpus, that are used for overhead canopy and windbreaks for the other more tender plants.

[beliz1985]

Who has still got that excel spreadsheet by @_Rich? :) 

[mdsonofthesouth]

Usda hardiness zones are a generalization in my opinion. For instance we are zone 7a but aside from freak events like this winter or 2012 or 1989 do we actually see zone 7 temps. In my opinion its a guideline for what to plant and not gospel.

[Reynevan]

Hardiness zone has changed also for my country ! It used to be 6a for bigger part of country, then 5 in mountainous region, 7a near the sea. Now it all raised by one degree !  
https://www.plantmaps.com/interactive-poland-plant-hardiness-zone-map-celsius.php