Have the zones changed recently

When I first started gardening, 6 months ago, I was in zone 8b. Now some places say 8a. Looking at the people who live in the same area I do, even the same city, half say 8a and the other half say 8b, and does it matter?

Hi Vicki,

I think it depends on which map you used to determine your zone. For here, I first listed 8b but switched to 8a. I'm not sure it matters a huge amount as long as you know your own garden. I think the main reason to use it here is it helps if you ask a question about growing something if everyone else has an idea what your climate is like. (There' s one Vancouver person I've seen who lists 7a. I think she must be in the foothills or out a bit someplace.) I actually prefer the Sunset zone maps because I think they are more accurate, but they're not national.

I got a little confused, too. I think the "a", "b" thing is used on some maps and not on others. I'm in the foothills of the Cascades outside of Seattle and I'm certainly a little colder than my friends who live 35 minutes away in Ballard. They're close to the water and have fewer trees. Things in Ballard bloom at least a week earlier than things out here.

Kathy,
Now that you mention it, I'm a little surprised that you are in 8b. By Sunset's measure, you're at least a zone colder than I am.

And I am south of Kathy, and live in the most fickle 7 a, b, c, d, e does it even matter anymore?
One of the charts I saw actually had us in zone 9. I wish.....

Yeah, there you go. I may have gotten it wrong, since I'm right on the border of the two zones. I'm not really sure anymore.

I can see that I'd be a little colder than you are. But then again, I'm only a few miles away from the valley and Duvall, so that might buy me a few degrees . . .

I use an indicator plant - Cordyline australis. It makes it in 9a and warm 8b but not all of 8b. If I don't see anything older than a year - it's a cold 8b or colder. Enough people plant it in the ground.

The past winter was, IMO, out of the norm.

This message was edited Oct 6, 2007 8:13 PM

Interesting. I almost added that in my last post as a way to make sure what my zone was - just didn't know what indicator plant to refer to. Thanks for the suggestion, growin', now I'm on a mission to find one. :-)

Here's one at English Bay where I'd say the zone is 9a. Just up the street at the gas station, the Cordylines toasted.

Beautiful. What a nice contrast to what we typically have here . . .

If you are any where the conversion zone is you will change from day to day. We in the zone know that if, a cold front is coming we will drop and certain areas will not, if you are any where in this zone it changes. In all the books I have we are just 8 where A & B came from I have know clue. And when I buy plants they do not say A or B.
Dont get it

The 8a/8b are maximum minimums on average. They change from year to year and from location to location. Reliable zones are typically areas close to the ocean or bodies of water which regulate changes to the temps. This past winter saw temperature fluctuations that were not typical of the Northwest. Most of my New Zealand plants took a hard hit as they are not fond of fast temp changes but are hardy. I had 2 Hoheria trees in 1 gallon pots a few feet apart. 1 toasted and they other was untouched. The difference was the proximity to the fence and protection when we went from +7C to -7C in 3 hours. 8a 10-15F/-9.5 to -12.2C and 8b 15-20F/ -6.7 to -9.4C. Exposure to wind can make a bit of difference too and change a sub-zone.

The other plant I use as an indicator plant for 8a/8b is Abelia. It's evergreen in 9a, semi-evergreen in 8b and deciduous in 8a from my experience. I'd be interested in your experience with this plant to its evergreen/deciduous habits by sub-zone.

Hi growin - abelia: have 3 very large (6 - 8') that are evergreen each year & have been since I planted them in 1992 or so. One is exposed to the max, another is on the north side of a fence & the third is very protected. Difference: the exposed one did not flower as much this year as the other two: they are all within 20' of each other. Even in 1996, when we had our ice storm , the large Abelias were fine.
I also have 2 short varieties: these were semi-evergreen this year, and obviously hit by the cold weather. Both in the ground 2 years, with other plants around them.
I am zone 7 at about 600' altitude, totally exposed to the winter winds, except for small portions of my property. My Phormiums all took a hit this past winter, but I had Cupheas come through like they lived in Northern California.
Go figure...plants are funny that way!

Maybe I'm thinkin' of the shorter one - think it's 'Edward Gautier' or something. Do you find it's evergreen unless you get a cold winter? I think the Phormiums took a hit more because of the rapid change in temps than the actual temps.

Abelia 'Edward Goucher' is designated for zone 7 - 9. It usually gets about 6' tall. I don't have this one. Mine were tagged as 'grandiflora' (?) and to reach 5 - 6' tall. But I have good soil, so everything tends to get larger than what the tags/books say.
Most of our winters are pretty close in temps to yours, just a bit cooler. I am east of Seattle, on a plateau above Lake Sammamish. The winds get radical some years, so i ahve lost more things to falling 30' branches & flying treetops than to the cold. Last year was so different from any previous winter: harsh & unforgiving. Yet, some plants did not take notice!
My Abelias have been reliably unchanged all these years. Only difference is in how well they flower, following a colder than normal winter. My friend has a couple Ed gouchers - they were fine, too. But she lives in a slightly warmer area than i do.
The Phormiums - yes, i believe you are correct- sudden temperature fluctuations would make sense. Nevertheless, it's all interesting!