Finally did some math...

15 years ago

OK, found the weather records for Knoxville finally and did the math. During the past 15 years, Knoxville's average minimum temp is 9 degrees. For the past 20 years, it is 10 degrees. Haven't had time to go past this point yet. This is the airport reading. My guess is that the 30 year for the new, extremely tardy zone map will but Knoxville at a 7a/7b transition zone. During the past 15-20 years, urban Knoxville has been 7b/8a. Subtract ~4 degrees for outlying rural areas. I have been reading past posts and it has come to my attention that many gardeners STILL DO NOT UNDERSTAND THE ZONE SYSTEM. IT HAS NOTHING TO DO WITH LENGTH OF GROWING SEASON, LATE FROSTS, ETC. There are areas of the Pacific NW the have shorter growing seasons than we do and are zone 8. IT IS NOT THE LOWEST READING OF THE 15 YEAR PERIOD. Subzero temps are occasionally recorded as far south as Atlanta and Birmingham. IT IS THE AVERAGE OF THE COLDEST READING OF EACH OF THE 15 YEARS (OR 30 YEARS). You do not need to wait for the USDA to tell you something that can already be demonstrated with available information. Go to Weather Underground and view the readings for yourself and do the math like I did. You're only cheating yourself by limiting what you can plant. Come by my house and I'll give you a tour of my subtropical plant collection...

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Comments (3)

brandon7 TN_zone7
15 years ago
...but Myrtle, I did the math and gave you these answers months ago. LOL. Oh well, a second opinion never hurts. Or, should I just say, I agree!
msbatt
15 years ago
I ignore the zones and plant what looks to me like it can take it---after I root a few cuttings, of course. (*grin*) Several years ago I was reading a gardening article where the author said he never believed that he couldn't grow a given plant until he'd killed it himself, at least twice. I'm hard-headed---some things I've killed 3 or 4 times...

Microclime is very important, too. I have plants that survive in my back yard that won't survive in my front yard.
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brandon7 TN_zone7
15 years ago
I don't have enough time, energy, or money to waste on plants that are very unlikely to make it. If I spent two or three years growing something and then it died because it wasn't hardy, I'd feel like I had wasted my resources that could have been more wisely spent on something that would have grown well. I'm not saying that there's anything wrong with trying whatever plant you want, but I'm extremely glad that I can benefit from other growers experience and get an idea of what plants are likely to survive before I spend what little resources I have on them.

The information that Myrtleoak is giving here lets you know that you can now grow things here that would not have survived a few decades ago. This information should be seen (at least so far as less hardy plants go) as liberating and not as limiting what you can plant, but it also doesn't mean that there are no limits. Plants rated for zones 9 or 10 have almost no chance of surviving long term without some type of protection (special microclimate, insulation, heat source, being moved inside during the coldest periods, etc).