CONFUSION ON HARDINESS ZONES

I went in to the members area, to see more about the members in my area. I couldn't help but notice that some of them don't know what their hardiness zone really is. Here is the USDA Hardiness Zone link for those who want to know for sure. You can even zoom into the map to get very close to where you are.

http://www.usna.usda.gov/Hardzone/ushzmap.html?

i think part of the problem is that the zones have changed in the last 5 years (due to climate changes) and the best map is still the 1990(made in 1960) version as the new one has a lot of problems and is not officially out yet. The 1990 map still shows where I live as zone 5 and I am now in zone 6. So you get a lot of conflicting information.
Mobi

Yes, I think Mobi has hit the nail on the head, for the most part. My zone on the 1990 map is zone 9a, on the new map it'll be zone 9. No problem there for me. I wish they would distinguish between zone 9 South and zone 9 West ...

But, when I go to gardening websites that ask me to put in my zip code, some of them tell me I'm zone 8. Go figure.

Also, I know that some members have said that although the region they are in is a particular zone, due to some local physical characteristic (a lake or something) their garden behaves a zone warmer, or a zone colder. Some times they reflect that in their info, since it's their garden we are talking about, not their area.

What ever works ...

Cheri'

ps welcome to the garden!

I live in northern IL right on the cusp of zones 4b/5a. I must say that for the past 7 or 8 winters, we've not had the extreme cold that our region can experience in mid-winter. For example, I recall in January 1994 there was a wind chill of -80 one day. Don't know what the actual temps were, but probably at the coldest end of the zone spectrum.
For a few years now we've had all that El Nino weather and it's been quite mild (comparatively speaking). If it ever hits the super low temps again, I'll probably lose some perenials aren't supposed to survive in zone 4 or 5...
So if there is a new zone map coming, they are rating your zone for the *coldest recorded* temps each winter, right? Or does it go by the *usual* winter temps?

Eileen

They are using average annual minimum temperatures. Which is one of the problems of the map. The American Horticulture Society, which is the one doing it, had made a lot of mistakes. I guess they had decided not to use some data. Here's a link about some problems.
Mobi
http://www.plantdelights.com/Tony/hardiness.html

Whoa!! I just went to the link at plantdelights and read the part about provenance:
"Did we mention anything about provenance? Provenance, in lay terms, means where did the parents come from? Just like parents and their kids, offspring bear some resemblance to the parents. Plants are similar, in that seed taken from a tree in Minnesota will be more cold hardy than seed taken from the same type of tree in Florida. Conversely the plants from the Minnesota seed source might never break dormancy in Florida, due to the lack of cold.
Many reference books may say that red maples are hardy from zone 2-9. Granted, there may be red maples growing in both areas, but to interchange seed from each area would most likely prove disastrous. This problem is particularly dramatic in woody plants that are grown from seed."

What about all those round robins?
Eileen

Like Sundry, I wish that the zones were divided in ways other than cold hardiness. There are lots of wonderful plants that do well in Zone 9 west coast that can't take the heat and humidity of the south coast. I know that a heat tolerance zoning is in the works, and I've seen some of those maps, but they aren't yet in wide use. Here's a link with something of a comparison of the two. http://www.selectseeds.com/zones.htm

Of course, the Sunset zones ( http://www.homestore.com/HomeGarden/Gardening/Landscaping/Zones/Climate/Index.asp?poe=homestore ) are more comprehensive, but not widely used and are somewhat more complicated.

Ya! We are though birds up here in th frozen north.
We are zone 4A. Last winter was very cold for a long time.
Never any snow cover. People digging in the winter, ie, graves, frozen sewers etc, said the forst line was 4 to 6 ft down. Normally it is around 3 ft. If you did not mulch perennials last winter they were pretty much history. Most winters zone 5 & 6 plants will survive here.
So you must take zones only as a guide.
Bernie

I like that sunset zone map. Sure do wish it was widely used.

Even the heat zone map doesn't take into account the moisture, which is like an entity in this area.

Cheri'

eileenmlamb: I've read about some seed traders who got lavatera and although it was supposed to be hardy in their area didn't do well because the seed came from a warmer zone.
I think you just have to experiment and realize not everything is going to come up as expected.

Mobi

From what I have learned, the USDA (Department of Agriculture) zone map is the one that you are supposed to go by. It hasn't failed me yet. I know that I'm 5b and buy my perennials accordingly. Indeed, there has been a warming trend over the last 10 years. I have noticed plants growing here that normally wouldn't survive our winters. However, I do know that occassionally we do get arctic blasts that will do them in. What really surprised me was someone in here from Cheney, WA (10 miles from me) saying they were zone 7. I couldn't figure that one out.

Thanks for the welcome! Nice website and neat people!

Karrie20x, I do think WA has about the most complicated zone map of US. I haave always thought Ilive in zone 5a. Usually we here are a little warmer than you in Spokane, however I think you receive more rainfall. This past summer was the hottest, dryest (spell) since they have been keeping records more than 100 years ago. My daughter in VA and i sure wished we could trade some of my heat and sun for some of her rainfall. She never had to irrigate this whole summer, and she never had a good tasting tomato either. Donna

I'm wondering if my zone is wrong. According to the US zones list I should be zone9a or 9b not 8

Donna,

We have very dry hot summers in Spokane, We also have set records the last two years.

I grow tomatoes all the time. The only thing I'm going to do different in growing them next year is I'm going to use those "wall-o-waters" to increase the length of my growing season.

I'm on the border of Idaho - very East, next to Coeur d'Alene., quite a ways south of the Wenatchee area (if that is where Tonasket is - not sure).

Ok - now I have an even BIGGER question regarding hardiness zones.

When you go into the Plant Database, and see the hardiness zones for a plant, and they have been added by we users, how do you know what resource they got their hardiness zone from? (As it obviously varies from the different resources that were listed above). So I think it would make it difficult for someone to tell whether they could really grow a plant from that list or not. (I think we should all be using the same zone chart in order for that to work).

Another thing I noticed about the hardiness zones in the plant database is that it shows the zone & the temps with a C. Is that C "Celsius"? If so, something very strange is going on there, because I know that things don't grow when it is 100 degrees below (faranheit). Has anyone else noticed that? Or does the C mean something else?

Does anyone know the answer?????

"C" should be celsius. I don't know about anyone else, but I always have to look up conversion formulas.

C=(F-32) x 5/9
F= (9/5 x C)+ 32
(I keep an old chemistry textbook handy)
8^)

The PDB now has both Celsius/Centigrade and Fahrenheit average minimum temperatures listed for each zone.

The zone information accuracy is up to the individual adding it. The editors do what we can to review new information being added, but we can't see/review everything, nor do we want to create a bottleneck by insisting that we review every piece of information that is added.

The upside to the open structure of the PDB is that we get a much wider variety of plants, images, and information than we would if there were a select "committee" creating a database.

The downside is that the information is provided by users, and while most are conscientious about checking their information before they add it, a few careless or inaccurate users can wreak havoc.

That's why we put the "report an error" link on every page of the PDB. Anytime you're viewing an entry and you see an error, please click on the link, and tell us what is wrong, (and what source you're using as the basis of your correction.)

Hope this helps answer your questions :o)
Terry

Okay, I went back in the PDB and typed in a common flower and it actually showed the C as well as the F. This particular flower looked a little bit more realistic on the temperatures. When I run into one that I think is way off, I'll click that "report this error" link.

The only other question I have left unanswered is if there is a way for everyone to use the same zone chart when saying it grows in their zone. I'm a 5b and saw another member who lives only 10 miles from me, and the same zone, state they were zone 7. So by looking at those zones, you really can't tell, by the PD, whether a plant will grow in your zone or not. You would have to seek the information elsewhere. I do understand that the people moderating Dave's site do not have the time to look up every single plant/species and analyze them.

If I am not mistaken, your state (Washington) has a rather confusing layout of zones because of changes in altitude, proximity to the ocean, etc. It is not unconcievable for someone to be in that drastically different of a zone in spite of close (nautical) proximity. See if you can find a zone map, maybe through your Cooperative Extension Service, of Washington.

As for everyone using the same map, it would be nice! 8^)
Unfortunately, even though they are all based on the USDA original, changes - some due to carelessness, others due to updates, others still to simplify the map - are made almost everytime a new publisher comes along.

Actually, the place I was referring to that is 10 miles away from me, gets even more snow than we do, and have pretty much identical weather. I am from the Eastern side of the state, away from those mountains and ocean, and so is Cheney, WA. Truth is, he had to have got his zone from a different chart. They are pretty much identical to us. I know this area very well. I just know that I can not trust the zones given in the database, because people are not using the same charts when they say where they are from and what grows there. It's quite simple. I almost feel bad for having brought up the subject. I will have to get my zonage information elsewhere in order to be certain. Not upset, just dismayed.

So much for my sense of geography! LOL

Karrie, if you find a neighboring member whose zone information that appears to be off, you can always contact them, and ask them about it. There are people who have created a microclimate for their garden, with walls, windbreaks, large ponds, etc. Who knows? Your question might blossom into a friendship with a new gardening buddy living nearby.

Karrie20X, Tonasket is in the Okanogan Valley. I live at 1450 feet, the valley floor is about 900 feet, which of course makes a difference. I live about 25 miles south of the Canadian border. Osooyos, BC, is in the banana belt, usually warmer than here. Donna

Karrie, one point of clarification - the USDA zones in the Plants Database should include the entire range in which a non-annual plant is hardy, regardless of where the person submitting it lives. For example, I may enter an Iris as hardy from 3a to 8b, and I live smack-dab in the middle of that range. I might also enter information on a succulent or tropical plant hardy only to zone 9b, or an evergreen shrub that grows in zones colder than mine.

Where we live has nothing to do with the plant's zone information we enter. Even if someone has indicated an erroneous zone on their personal information, it doesn't mean the range of zones they enter is incorrect (nor can you see who entered a particular range of zones in the PDB.)

If you find that the range of zones is incorrect for an entry, please let us know, and we'll review and correct it.

The USDA zones should not be confused with people entering their ZIP codes to indicate what grows well for them in their garden. That data doesn't relying on the USDA zones, but is instead building a database of specific areas where plants grow well (Since my zone 7a climate is very different from someone in the PNW who also lives in USDA zone 7a.)

I don't think you understand what I am saying about the zones. Of COURSE they should have all the zones listed. But if a person is on the EDGE (like coldest or hottest) that that plant will over-winter in, and put's a different hardiness zone than they really are, it may confuse others who actually ARE in that zone & cannot actually grow the plant. Like the thread said "Confusion on Hardiness Zones" - I am having a HECK of a time trying to explain this. I give up. It's not worth the headache. People are not understanding what I am trying to say it. It has nothing to do with zipcodes, it has to do with DIFFERENT zone charts out there that aren't the same, that people are using, thus it is mixed up zone information in the database.

you are talking about micro climates. I think which is a pocket of warmth or cold within a zone either making it colder or warmer than your 'neighbors'.

for example

A person in zone 8 (plus) like me can grow things better than someone 20 miles away on the Antrim Plateau who gets harder frosts and more snow which stays a lot longer than with me. They should be zone 7 or less

I get what you are saying, Karrie.

I think what Terry is saying is that the zone info in the PDB is pretty much the published info on those plants, and pretty much gets checked by the admins. Corrections get made. Anyway, I think most of us are using the old map, which is still the current map (which is highly inaccurate). When you are on the edge of a plant's zone limit, it's a gamble, no matter what map you use.

Anyway, if I were to add a plant to the PDB and it was only rated to zone 10, the fact that I grow it would not cause me to claim that it was hardy to zone 9. I would input the information that was available to me, putting my personal experience where appropriate. When in doubt, leave it blank.

So, the zone next to my name is not necessarily the zone I'd use in the PDB ...

Cheri'

One of the concerns that I've had about the new map is what I think Karrie may be trying to express.

I'll use myself as an example: I was zone 6b on the old map. I'm zone 7 on the new map (there are no a/b sub-divisions on the new map.)

Over the years, I've watched "zone creep" occur with plants - they gradually get rated hardier and hardier as gardeners farther north experiment. So let's say a plant that WAS considered hardy to zone 8 is now generally noted as hardy to the (old) zone 7. That's all well and good until those who were on the border of 6a/6b decide they're now "close enough" to zone 7 to consider themselves in that new zone. So a plant that was marginally hardy to the edge of zone 7/8 is meeting up with people who should be sticking with plants hardy to zone 6 or higher. It could mean some disappointed and confused gardeners if/when we encounter a colder-than-normal (at least the NEW normal) winter.

Karrie, please hang in there with us. It IS a confusing issue, but it's certainly gained some attention, and the more we get people talking, the more we all learn :o)

I guess my main concern is WHAT maps people are using. I use the USDA one. There are others. I do know for a fact that on the USDA one, Cheney, WA is not a zone 7. It is 5b just like me. Cheney, WA is located in Eastern, WA about mid way down the state. There is NO way that that person is a zone 7 and if that person went to select plants, that person could get some that will not survive his or hers harsh winters. I wonder what map that person got their information from. It wasn't from the department of agriculture.

So if there are different maps out there being used by gardeners in the PDB, there will be inaccurate information. The only way it can be accurate is if we are all using the same map.

Well, to further confound us, the Sunset zones are numbered 1-33, and parts of Washington and Oregon are located in zones 5-7, which can definitely cause more confusion for those who live in that region: http://www.getnet.net/~richarde/cactusstore/Sunset%20%20Zone%20Map.htm

Long story short, there will never be one map agreed upon by all gardeners throughout the world or even the U.S. Which is one reason why we include minimum temperatures and specify that we use USDA zones; we've done our utmost to provide readers with a solid basis for interpreting the zone information.

In all honesty this problem is not isolated to the Plants Database; to discount it as potentially inaccurate means you also have to suspect all other sources as equally unreliable unless you know precisely where they obtained their information, and what map they are using. Whether one chooses to use the information presented within the PDB or not is a matter of personal preference, but I would vouchsafe for its integrity and general accuracy against all other online sources of horticultural data. JMHO :)

I think the PDB has helped me in many ways. What I have to do, as well as any gardener, when looking into a particular plant, is to gather information about it from many sources. (I have a plant encycopedia that I have even found incorrect for some plants). I would never want to discredit the database. What I would WANT is for us to all use the same zone chart. If that isn't possible, then so be it. :)