fruitnut, I've always thought the reverse with regard to extreme cold in the humid east versus arid west, but I guess it really has much to do with the plants in question. I'm thinking more about things like cacti, tree yuccas, desert willow, desert bird of paradise, and others that make it here well beyond their zone designations (all of these survived a zone 4 winter last year) but would have a hard time in the Northeast. In terms of figs, I wonder if being so far south (lots of warm days in winter) is a problem with proper hardening off. Large fig trees in Albuquerque don't die back in average winters with a night or two in the single digits. Last winter was different with temps below zero, and 88 consecutive hours of subfreezing weather in the city. Both figs and pomegranates were killed back significantly.

You need to remove the period (full stop!) at the end for that URL to work. It really isn't that high rez. anyhow. But also, even more than the USDA hardiness map this AHS heat map is of very limited utility. Number of days over 86F is essentially meaningless for a lot of plants. Right off the bat, it would have made more sense to plot the average summer nighttime dewpoint temperature. At Sonoma Horticultural Nursery in - surprise surprise - Sonoma County CA, they can grow the Himalayan cinnabarina series Rhododendrons. Or the hardy big leafs like R. rex. At Rarefind in NJ, you cannot. Even the ones that would be winter hardy there. The two locations probably have a similar # of days above 86F, but their summer climates are hugely different as are their winter climates. The cool nights and lower dewpoints in Sonoma County make all the difference.

Marilyn, thanks for the link! I really enjoyed the interactive link where the map changes from the old to the new - very cool. We're still a zone 8 but I have noticed the last couple of summer have been a bit warmer. And I think fall is longer, pushing winter for us into Jan. when it used to begin in Nov. One thing to remember about these zones is that they're just a starting point for determining what to grow. Almost all homes have micro climates in which plants from a zone higher or lower will grow and flourish. For instance, the west side of a home will often be much warmer due to the hotter afternoon sun that hits it. I have a hard time growing crape myrtles - they generally sit and sulk and take forever to grow - but the ones on the west side of my cottage do fine. Not as well as they do in a warmer 9 or 10 but they don't take forever to flower like they do on the rest of my property. Also, one person's zone is not the same as another's of the same number. My zone 8 is very dry so I don't experience the mildew, rust or insects that many do in the more humid zone 8 areas. I also don't get the triple digit temps that a zone 8 in Texas does but I do get snow and winters temps in the single digits. I'm also at a mile high elevation so while I don't get the heat my plants can scorch from the intense sunlight. Then there is the wind - don't get me started on what it can do to plants - ugh! Diana

Gusolie: Didn't see your reply till just now! You are correct, I am growing Owari Satsuma mandarins. And you are right on your other point- it does matter what type of mandarin. I have a few mandarin trees that I grew from seeds from a grocery store fruit, and these were killed almost to the ground in their first winter outside last year. This summer they have completely recovered, grew new branches and leaves. These seed grown mandarins were basically for experimentation anyways. My hope is that they will grow as a low bush instead of a tree, as the freezing winds seem to be the biggest cause of damage.