I can only speak for zone 5, that being the one I've looked at most closely, and my sense is that it's relatively useless when applied to herbaceous plants. For example, Oswego, New York, Peoria, Illinois, Omaha, Nebraska and Denver, Colorado are all in zone 5. Oswego's average high temperature in July (the hottest month) is 78F; Omaha's is either 85 or 87F (I used these numbers in a recent talk, and I'm working from memory here). Omaha's average precipitation from October through March is a bit over 8 inches; Oswego's is around 21 inches, and a lot of that comes down as snow (for an average annual snowfall of around 120 inches). In short, patterns of precipitation and temperature can differ widely within one zone (and that doesn't start to address variations in soil, ecosystems, etc). I can grow lots of South Africans in the ground here, because the ground either doesn't freeze or, at worst, doesn't freeze very deeply, and summers are moderate and not terribly dry. A Great Plains "zone 5" (Omaha) would, I think, be terrible for my high-altitude Drakensberg summer-rainfall plants. This does not make my zone 5 somehow less valid; it simply illustrates what information "zone 5" doesn't convey! As a nurseryperson, I would LOVE to be able to chuck zones altogether, and encourage people to substitute intelligent thought and experimentation; but it will not work. It's a sorry state of affairs... Ellen Hornig Seneca Hill Perennials http://www.senecahill.com/ Oswego, NY USA Zone 5 Original Message: ----------------- From: John Bryan johnbryan@worldnet.att.net Date: Thu, 27 Oct 2005 10:41:19 -0700 To: pbs@lists.ibiblio.org Subject: [pbs] Climate Zones. Dear All: I wonder what your opinions are about the USDA Climate Zones. I also wonder why such zones cannot be linked with our zip codes, or postal zones. Would they not then be better defined? Cheers, John E. Bryan _______________________________________________ pbs mailing list pbs@lists.ibiblio.org http://www.pacificbulbsociety.org/list.php -------------------------------------------------------------------- mail2web - Check your email from the web at http://mail2web.com/ .