Talk:Hardiness zone

message: Hi, just thought I ought to introduce the "Cold Hardiness Zone Map of the British Isles" It's been around for many years now, but you evidently haven't seen it. The map you have for the UK is basic and only shows the 4 zones. It's sort of correct, but the British Isles is far more complex than that, which the "Cold Hardiness Zone Map of the British Isles" has done a lot to rectify. You may contact the administrator of the site for a flat image if you so wish. — Preceding unsigned comment added by 82.152.178.81 (talk) 10:32, 11 April 2007 (UTC)
thread_title: Hardiness zone map of the British Isles

message: Despite the warming effect of the North Atlantic Drift on the British Isles, somehow the Shetland Islands and truly subtropical southern Alabama having the same hardiness zone did not seem right to me. Looking at the USDA hardiness zone map for southern Alabama, it shows it as mostly 8a (10-15° F average minimum), with the Mobile Bay area as 8b (15-20° F average minimum.) The US system is defined with Fahrenheit ranges and the UK system with Celsius ranges. Compare this to the Shetlands on the 8-9 boundary of the UK system, or approximately -7° C average minimum (19.4° F.) While the annual minimum temperature in the Shetlands is similar to Mobile Bay, the average winter temperature of the latter is greater due to greater daily ranges and higher daytime winter temperatures. Heff01 04:58, 16 August 2007 (UTC)
thread_title:  US and UK hardiness zones compared 

message: The USDA updated the US Hardiness Zone map in 2003, it led to significant reclassifications in the the Deep South, including moving Atlanta, Charlotte, Birmingham and Memphis from Zone 7 to Zone 8.   I cannot find a 2003 map that is from a source eligible to be uploaded to wikipedia.  I have also searched for an Australian, NZ and South Africa hardiness zones map and found a few, but whereas the maps were from the respective Australian, NZ or South African government, I could not update them to Wikipedia in the same manner that the US Government publications are open source and eligible for publication here.  Any Ideas?  —Preceding unsigned comment added by 24.126.132.88 (talk) 12:07, August 24, 2007 (UTC) 
:Try this for Australian/NZ/SA hardiness zones:  — Preceding unsigned comment added by Heff01 (talk • contribs) 01:20, 15 October 2018 (UTC)
thread_title:  US Hardiness Zones 

message: Since there's apparently a discussion going on about merging some articles, I don't want to upset the apple cart. However, I would suggest that any new article contain a somewhat more fleshed-out reference to Sunset Climate Zones, also known as the Western Plant Climate Zones. 
In the western US this system is used almost exclusively by gardeners. I'm a pretty avid gardener and have been for 30 years, and I had actually never even heard of the USDA's zones until about 2 years ago. 
I would add something myself but as I say I'm not entirely clear on the status of the merge being discussed above. Thanks. Gilajones (talk) 01:35, 8 January 2009 (UTC)
thread_title:  Sunset Climate Zones 

message: As is correctly stated in article, the US hardiness zone system, based on coldest winter temperatures, does not work well in northwestern Europe - Norway, Iceland, Faroe islands, partly also in Sweden, etc. In Norway and Sweden there is a different system based on both summer warmth and length and winter cold. These zones are named H1, H2 and so on to H8, and there is also a mountain zone, where gardening is more ore less pointless (unless using only arctic-alpine plants). H1 is the warmest, H8 and mountain zone the coldest. The latest map uses updated climate data. For instance, Malmø and Gothenburg and Karlskrona are all H1, Stockholm are mostly H2 as is Gotland island; Karlstad and Uppsala H3, Gävle H4, Umeå H5, Østersund H6 and Luleå at the H6-H7 border, Haparanda H7, Vilhelmina H8 and Kiruna in the mountain zone. 
For Norway, Mandal, Stavanger and Bergen are H1, Kristiansand, Tønsberg and Ålesund are H2, Oslo (lowland near the fjord), Norheimsund in Hardangerfjord, Molde and parts of Hitra island are H3, Trondheim, Hamar and sheltered locations in Lofoten archipelago are H4, Lillehammer, Mosjøen and Fauske are H5, Harstad H5-H6 border, Lom, Mo i Rana and southern part of Senja island H6, Oppdal and Tromsø H7, Alta and Geilo H8, Røros and Karasjok in the mountain zone. As seen, the result is quite different from the US system. Oslo is here in a much milder zone than Tromsø (due to warmer, longer summer), and this is of course correct. Oak trees grow well in Oslo, but would strive to survive in Tromsø and grow very, very slow. As with all such system, the local microclimate can vary a lot depending on shelter or windy location, sun exposure or shadow, etc - even the same garden can have different microclimates. 
Here are some examples for well known plants: The hardiness of European beech - Fagus sylvatica - is H4 (inland) and H5 (coast). Quercus robur is H5 (inland) and H6 (coast). Norway spruce is H8 and Blueberry grows well into the mountain zone. Taxus baccata is H4 (inland) and H5 (coast). Sequoiadendron giganteum is H3. Prunus persica is H2-H3. Apple trees (able to ripen fruit) varies from H3 to H5 (a few even nearly H6), and are commonly used in private gardens at least up to H4/H5 zone. Orcaborealis (talk) 20:12, 22 January 2009 (UTC)
replies: text: I have to say I have never heard about these H1–H8 zones being used in Sweden. Does that system have a name? Unless things have changed very recently, the only one in use among amateurs in Sweden is the one with the zones named I–VIII: . I know it as created by Sveriges Pomologiska Förening, but there seem to have been name changes and mergers semi-recently, so it's now © Riksförbundet Svensk Trädgård (and bloody expensive to reproduce). JöG (talk) 22:43, 25 September 2009 (UTC)

text: But my real point (and possibly Orcaborealis's too) is that it's not really helpful to have the article speak about zones in Scandinavia and implicitly use the US system. Might be mildly interesting to US citizens, but to the rest of us, statements like "Pajala is in zone 3" at best carries no information. JöG (talk) 22:51, 25 September 2009 (UTC)
replies: text: You are right, the US system used in Scandinavia carries very little information, as summer warmth and length is very important in Scandinavia. And yes, I was referring to the same zones you linked to. In Norway, we use H and then number, but it seems only the number is used in Sweden, which you probably know quite well. My reference is the map produced by Det Norske Hageselskapet in Hageselskapets sortsliste (Media Øst, 2005, ).Orcaborealis (talk) 12:10, 27 September 2009 (UTC)
replies: text: I've never heard of this system being used in the UK either. It may be used by professional horticulturalists and other specialists but the general public is completely unaware of it. I'm an amateur grower and haven't seen the concept used in books or online forums. --Ef80 (talk) 10:09, 5 May 2010 (UTC)
replies: text: It is the same system in Sweden and Norway. A map for Norway here.Orcaborealis (talk) 07:07, 6 May 2010 (UTC)

text: Another factor which complicates the usage of Hardiness zones, particularly in Scandinavia, is snow cover. A plant, typically a perenial, might not survive -5°C in claysoil without snowcover, but survive -20°C in well drained soil as long as there is a good and stable snowcover. TorKr (talk) 10:28, 17 March 2019 (UTC)
thread_title:  Northern Europe (Scandinavia) hardiness - the system used locally

message: In the article text, under Australian Hardiness Zones, appears the following:
"...Sydney residents can choose between Zones 3a and 4b."
The numbering of zones is stated to be based on an area's average annual minimum temperature in degrees Celsius. 
Wikipedia's own article on Sydney clearly shows Sydney's mean minimum temperature as 13.8 degrees Celsius, far above -40 or -35 degrees. It's not even a simple use of degrees C instead of degrees F, because both scales are the same at -40. Should we need a discussion on the difference between mean and average, I would postulate the difference between the two is unlikely to be around the 54 Celsius degrees mark.
The article also alleges:
"As an example, Quebec City in Canada is located in zone 4 but can rely on an important snow cover every year, making it possible to cultivate plants normally rated for zones 5 or 6, whereas in Montreal, located in zone 5, it is sometimes difficult to cultivate plants adapted to the zone because of the unreliable snow cover."
According to http://www.australiasevereweather.com/links/temprec/sydney.htm Sydney's lowest minimum temperature since 1859, was 2.1 on June 22, 1932.
How can Quebec City, with an average January low of -17.6C, be in a higher rated zone than Sydney?
Is there some sort of misprint with the table? 
If there is not, then the whole idea of Hardiness Zones, as described, seems pointlessly inaccurate.
What am I missing here? Or is the article a furphy?
Bigharps (talk) 05:29, 29 May 2009 (UTC)
replies: text: Read the article. Quote: Australia numbers its climate zones differently but these can be made roughly equivalent to North American hardiness zones by adding an offset of 6. For example, Australian Zone 3 is roughly equivalent to North America Zone 9. The higher Australian zone numbers have no US equivalents. So Zone 3 in the Australian system is roughly equivalent to USDA zone 9.Orcaborealis (talk) 17:58, 29 May 2009 (UTC)
replies: text: Still, Zones 9 and 10 are shown as having average minimum temps of -7C and -1C. Even with the offset of 6 positions, this does still not relate in any way to Sydney's average minimum of +13.8C. I can only assume this rating impractical for Australian conditions, except for the minuscule alpine areas ? Bigharps (talk) 05:07, 30 May 2009 (UTC)
replies: text: The cold-hardiness of plants depends on the temperatures that the plant has to survive during the winter.  During the winter months,  the typical daily minimum temperature in Sydney is around 5 or 6 degrees.  Actual frost is quite uncommon in Sydney proper. I have no idea what that 13.8 C figure you are quoting is.Eregli bob (talk) 04:59, 19 May 2012 (UTC)
replies: text: The average minimum of 13.8 C you are quoting for Sydney,  is obtained by taking the minimum temperature occuring on all of the 365 days of the year,  and averaging them.  So if the daily minimum is 20C in summer,  and 14C in the spring and autumn,  and 5C in the winter,   if you average those over the whole year,  you get 13.8 C.    This is a completely different statistic to the average extreme low temperature which is the basis for the horticultural zones in North America.   The typical winter daily minimum in Sydney is 5 or 6 C and the typical annual worst-case temperature is about 1 C. — Preceding unsigned comment added by Eregli bob (talk • contribs) 05:41, 19 May 2012 (UTC)
thread_title:  How accurate are the tables in this article? 

message: It is great that the USDA has made its own conception of plant hardiness zones in Canada, but the relevant source for Canadian zones is really planthardiness.gc.ca, from Natural Resources Canada.  This exists only in a link at the bottom of the page, but it should be written about in the North American section of the article.  —Preceding unsigned comment added by 68.148.129.210 (talk) 18:50, 10 January 2010 (UTC)
replies: text: The North American Zone section states twice that it was updated by USDA in 2012.  Following the links and crawling through the USDA website would indicate that the update was for the United States only.  Provide a link to the complete 2012 updated North American zone data or indicate that the update was the United States only.Sandboo (talk) 13:59, 11 March 2012 (UTC)
thread_title: North American Zones

message: There is an interactive version (uses google maps api) of the 1990 USDA plant hardiness zone map that may be a better reference for readers than the static version currently listed.  There is also an interactive map for the UK and Ireland using USDA classifications.  —Preceding unsigned comment added by Peterusso (talk • contribs) 21:16, 28 February 2010 (UTC)
thread_title: External Links

message: I changed the Boston hardiness zone to 6 (from 7), as per the USDA hardiness map at http://www.usna.usda.gov/Hardzone/hzm-ne1.html  —Preceding unsigned comment added by 66.31.55.186 (talk) 03:48, 23 March 2010 (UTC)
thread_title: Boston hardiness zone

message: I had never heard of the "Australian System" until I read this page.  All the documentation I have seen uses the USDA system.  I've modified the entry in the following way:
*Mention both systems.
*Link to ANBG article about Australian zones.
*Remove irrelevant reference to the dryness of the continent.
*Remove copy-and-paste of zone summaries from the ANBG article.
I also recall seeing another system again, based on the dryness or average top temperatures, and used in conjunction with the USDA system.  I think Diggers Club uses it, but I can't find any reference to it offhand.  Can anybody help? Groogle (talk) 23:14, 10 November 2010 (UTC)
thread_title: Australian Hardiness Zones

message: Average annual minimum temperature means what, exactly ?    An average of the daily minimum temperature taken over all of the days of the year ?   Or the minimum temperature of the coldest day of the year,   averaged over a number of years ? Is this based on standard temperatures taken 1.6 metres above the ground level,   or ground level temperatures ?Eregli bob (talk) 04:51, 19 May 2012 (UTC)
replies: text: Answered my own question,   they get the coldest temperature occuring on the coldest day of the year,   and then average that number over at least ten years.   So the average annual minimum temperature is the expected  value of the coldest temperature you are likely to get in a year.   Also,  about half of the years,  you will get something a bit colder.Eregli bob (talk) 05:35, 19 May 2012 (UTC)
thread_title:  Average annual minimum temperature 

message: I've updated USDA hardiness zones for a few cities in the "U.S. Cities hardiness zones" section with results directly from the USDA website (and more of them should probably be checked):  http://planthardiness.ars.usda.gov/PHZMWeb/ 160.111.254.17 (talk) 19:18, 3 December 2012 (UTC)
thread_title: US cities

message: I was dissapointed to find out there's a section on Northern and Central European zones, but nothing on southern european ones. Yet the Central european zones includes well known non-central places as Malaga and Madrid. How about a more generic heading, even if more info on certain areas is yet to appear? Mariannep (talk) 11:44, 20 March 2013 (UTC)
thread_title:  Northern bias?? 

message: THERE IS NO WAY THAT LONGYEARBYEN IS IN A HIGHER NUMBER ZONE THAN MOSCOW WHEN MOSCOW IS WAY WARMER IN THE WINTER AND IN THE SUMMER. EITHER PUT LONGYEARBYEN AT 3 OR LEAVE IT AT 5 AND PUT MOSCOW AT 6. SORRY MOSCOW CAN GROW TROPICAL PLANTS A LOT BETTER THAN LONGYEARBYEN. THAT IS TRUE. IT'S DAMN TRUE.I LOWERED LONGYEARBYEN TO 4 UNTIL YOU DO THE ABOVE. MOSCOW'S WINTERS AND SUMMERS ARE WAY WAY WARMER THAN LONGYEARBYENS AND THUS PLANTS DO BETTER IN MOSCOW THAN LONGYEARBYEN.I WILL NOT LEAVE THIS ARTICLE UNTIL I GET MY WAY  — Preceding unsigned comment added by 68.84.240.18 (talk) 21:37, 29 November 2014 (UTC)
replies: text: Source? - SummerPhD (talk) 13:03, 15 January 2015 (UTC)
thread_title:  PUT MOSCOW IN A HIGHER NUMBER ZONE THAN LONGYEARBYEN 

message: The US hardiness zone system stops at 12b (55-60°F.) 13 is possible in the tropics, particularly small island locations. Heff01 (talk) 03:34, 26 May 2018 (UTC)
thread_title:  Zone 13 

message: Add Fort Yukon, Alaska, and International Falls, Minnesota, which have Zone 1a and 3a hardiness that no others on the list do. Barrow is included but it's actually warmer on the north coast of ak, making some of the several Alaska examples redundant. Barrow is small and northern mn is coldest in continental us. B137 (talk) 16:06, 23 April 2020 (UTC)
thread_title:  Add two cities to example list 

message: What happened to that picture that showed the difference in hardiness zones from the 1990 to 2012 Maps? It had shades of red and white and showed that much of the area moved up a half step. — Preceding unsigned comment added by B137 (talk • contribs) 16:21, 23 April 2020 (UTC)
thread_title: also

message: The article appears to contain much original research. In order to state that a particular place is in a particular zone, it must be verifiable in a reliable, published source. It's not acceptable to use sources that only give temperatures but not a specific hardiness zone, to determine the zone. For example, I see that  and  have recently been debating, in edit summaries, which zone Rome belongs in. It is not up to Wikipedia editors to determine this. The data must be based on a published, reliable source that specifically states the zone.
I have also removed the citations of unreliable sources from the "Selected European cities" section, for the reasons given in my edit summary: . In almost all cases, the numbers in the table didn't match any of those sources anyway. Unless reliable sources can be found, this table should be deleted. --IamNotU (talk) 14:31, 24 July 2020 (UTC)
replies: text: Hey , the user  is a sock of Weathertrustchannel and has multiple accounts vandalizing Italy related pages, he's blocked now. Some of the cities that were recently altered (until 29 June) are not really original research, I took the official average lowest temperature from historical values (usually last 20 years) on the German Meteorological Service website, you can find it here: https://opendata.dwd.de/climate_environment/CDC/ but still, cities like Rome don't appear on this website, having another website as a source is a bit unreliable as they all seem to differ. So I think the best think to do is to go by DwD if the station is in the city itself, if not then just go by comparison. I had a talk with another user regarding this for spanish cities and it's in my talk page if you'd like to read it. Average Portuguese Joe (talk) 18:40, 24 July 2020 (UTC)
replies: text: , thanks for letting me know about the other user. I do appreciate the work you've done to help improve the article, but the original research policy, specifically the section on synthesis, is quite clear:  Using the German Meteorological Service source, which gives temperatures but doesn't mention hardiness zones, combined with another source that gives a definition of hardiness zone temperature ranges but doesn't mention specific places, in order to reach a conclusion that place X is in zone Y, does exactly that. Although the conclusion may seem obvious, it's not allowed, because users must be able to verify the conclusion in a source that has explicitly published the hardiness zone values, as is the case for the North American data for example. Editors may make only very basic calculations; this goes far beyond that. Considering the explanation you've given above, and on your user talk page, about how you (and others) have calculated (and debated) the zones for each European city yourself, I'm going to remove the table as original research. Sorry about that. --IamNotU (talk) 15:03, 25 July 2020 (UTC)
thread_title:  Original research 

message: This section has been disputed since its introduction in this page and the entire paragraph didn't have any source, the unsourced tag was added in September 2020 and in 9 months no one has added any source and several users have been complaining about this section. It definetly gets deleted unless if it gets better veracity backed up by sources. I recall the recent edits of  (along with other users in the past) but this is the most recent dispute, and I support his point of view, also "Macaronesia" is only the name of an archipielago, it's not an official region. Even the Cape Verde islands are included in Macaronesia, and that's an African country so this definition has clear leaks. There isn't even a Wikipedia page for European Macaronesia because such a "region" doesn't exist.
The Canary Islands and Madeira are entirely based in Africa (tectonic plates) while the Azores are mixed up between the European/Eurasian and the American plates, but they're still way too far from continental Europe. Macaronesia doesn't form a continent or a part of Europe, at least officially, so Madeira and the Canaries should be added in Africa and Azores are a mixture. This section needs proper sources and in any case it shouldn't be included in the European section. Because in that case, we also need to start including all European overseas territories because officially, Azores, Madeira and the Canaries are Outermost regions of the European Union because they're not located in Europe, unlike the Balearic Islands, for example. --TechnicianGB (talk) 13:54, 23 June 2021 (UTC)
replies: text: First of all I wouldn't remove anything before I had reach consensus. I'm unaware of any dispute on this section. Where do you want to include this geographical region? Just like the United States includes Hawaii, I think the best option is to include the Azores, Canaries and Madeira in the "European hardiness zones" section, whether it would be in its own subsection (as it was before) or in the "Southern Europe" section, because, after all they are part of Portugal, Spain and the European Union. Heck even French Guiana should be included in Europe. The location doesn't matter. Maybe instead of "Europe" we could call it "European countries"? or put a disclaimer that this also includes territories that are outside geographical Europe. Continental plate is not an excuse to exclude those places from Europe, Sicily, or Malta are on the African Plate. Average Portuguese Joe (talk) 16:00, 23 June 2021 (UTC)

text: Well I tried to reach a conclusion but, again, since you don't seem to have any answer for that I will include Macaronesia in its own section with proper sources. Its funny you say its unsourced when there is literally your prized source in there, but there shouldn't be any problem now, right? Average Portuguese Joe (talk) 19:15, 23 June 2021 (UTC)
thread_title:  "European Macaronesia" doesn't belong in this page. At least not inside of Europe. 

message: claims I am "nitpicking" areas part of zone 11. Lets be clear, zone 11 is clearly different from any other zone in Europe, it is much more uncommon and it's even controversial to say that there are regions part of zone 11 in Europe, so if there is evidence of any, they should be described with detail, and not as "some areas in southern Spain", as the truth is, many of these so called "areas" are in fact populated centers (a.k.a UHI), but that is a whole 'nother subject. The point I am trying to make is, there is no "nitpicking" excuse when it comes to zone 11 in Europe. There is no global support for this zone to even exist in Europe. I await the answer of a third party. Average Portuguese Joe (talk) 19:09, 23 June 2021 (UTC)
thread_title:  "Nitpicking" instead of generalizing zone 11 

message: I didn't see an explanation for this. Looked at the table in the European section. 37.76.57.249 (talk) 16:51, 18 August 2022 (UTC)
replies: text: See here. Uness232 (talk) 21:47, 19 August 2022 (UTC)
thread_title:  What do the letters a and b mean? As in 6a and 6b. 

message: @Heff01 I am wondering how long you would like the list to be. Right now, it is a fair bit longer than the European list and in my opinion, your constant additions are causing it become unwieldy and unproductive. Uness232 (talk) 16:46, 11 February 2024 (UTC)
replies: text: Fair; I am a little concerned about its length though. Any more than 10 more cities added from now is, I think, overkill. It is important to note that just like us, readers also have the map at their fingertips. Uness232 (talk) 17:04, 11 February 2024 (UTC)
thread_title:  Selected American cities list