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pricklypearsatx

Hardiness Zone Changes

pricklypearsatx
16 years ago

Remember last year, when the Arbor Day Foundation came out with a new Hardiness Zone Map?

Many of us in Zone 8b, were put in Zone 9a.

The 2006 Arbor Day Map reflected weather changes since 1990.

So, I began to wonder if there was a hardiness map prior to 1990???

With some work, I was able to find a 1960 USDA Hardiness Map.

Most of South Central Texas, San Antonio and Austin were already in Zone 9 in the 1960 Map. Apparently, cold winters in the 1970's and 1980's put us in Zone 8 in the 1990 map.

Here is a copy of the 1960 USDA Hardiness Map:

(Zone 4/5 is color coded because I shared it with a friend in Wisconsin.)

Comments (9)

  • cweathersby
    16 years ago

    Thanks for posting this!
    That is really some cool information to know. In my area it seems like we were clearly in zone 8 back then, and now we are back in zone 8. That's great news for me, cause many of my favorite plants are not hardy in zone 7. Maybe those cold winters of the 70s and 80s won't come back for a while.
    I do remember much colder winters back then, but I was just a kid and didn't garden yet, so I wasn't keeping track of how cold. I just remember getting to use the sled almost every winter.

  • lou_spicewood_tx
    16 years ago

    Yep. That 1983 and 1989 winters screwed it up. :)

  • pricklypearsatx
    Original Author
    16 years ago

    I remember 83 and 89. In 83, I had just moved here from Wisconsin, so as far as I was concerned, it was warm.

    Remember 1985? That was a wild one in San Antonio.

    It snowed 3 times that winter. One snowstorm gave us 14 inches of snow!! Even by Wisconsin standards, a 14 inch snowstorm without snow plows is extremely dangerous.

    Since then, we haven't had snow. My kids have never seen snow.

  • lou_spicewood_tx
    16 years ago

    One day it will snow... you just never know. I have a hunch that it will come soon rather than later. I never expected to see snow during April in Dallas area this year. It was really weird seeing all the snow while everything has already greened up.

    I can't remember all the details. I was born in 1976 so it's not like I was really into weather back then except for winter when I wanted snow IN HOUSTON. It doesn't happen very often. LOL.

  • annieinaustin
    16 years ago

    What an interesting thread! We moved here in 1999, so have seen some snow and ice in Austin, and while missing the super-cold winters in Texas, sure had them in Illinois.

    I found a zone map made in 1936 if you'd like to see what's supposed to be the earliest national version.

    Annie at the Transplantable Rose

    Here is a link that might be useful: 1936 Zone Map

  • pricklypearsatx
    Original Author
    16 years ago

    Annie:

    That old map is interesting.

    I think it did mean something different.

    I wonder if those old maps were for "agriculture"?

    The average minimum temps are probably the average of the daily temps., as opposed to the coldest temps of the year.

    Generally, our average winter morning low on any given day is about 40-50 degrees.

    I think that's what it means. I'm from Wisconsin, and that map would have put WI in zone 2. The "average" winter morning was probably 0-10 degrees. However, that map doesn't include the real temps which usually included at least two weeks of significant subzero temps. Anywhere from -5 to -15 was not unusual.

  • annieinaustin
    16 years ago

    Hello pricklypearsatx,

    My husband has been looking around, trying to find exactly how these numbers were derived - and you could be right that it's an average for a season. As you noted, the text mentions the limits for growing certain crops, but the real temps were what counted when it came to having our garden plants live and bloom both in Wisconsin and in Northern Illinois where I gardened. Just one night of -16ºF and there would be no forsythia that spring.

    Annie at the Transplantable Rose

  • pricklypearsatx
    Original Author
    16 years ago

    Annie:

    It has been awhile since I posted. I grew up in Wisconsin but didn't garden there. (But I still miss it.) The type of plants they grow such as forsythia etc., are so different than what we grow or attempt to grow here.

    We pretty much know during the winter when we've lost a plant.

    I can't imagine waiting until spring to see if my plants survived etc.

    I think when those maps were written in 1936 they assumed the "home gardening" information was exchanged via the picket fence etc.

  • annieinaustin
    16 years ago

    We used to vacation at places like Devil's Lake - your Wisconsin is a beautiful state, pricklypears.

    I suspect that gardeners back then were also unable to resist marginal plants and then had to keep their fingers crossed! No matter what zone we live in, we want to grow what belongs to the next zone, it seems.

    BTW, the -15 degrees F. wouldn't have killed the forsythias themselves - just the flower buds. In the late 1980's/early 1990's the outer suburbs of Chicago might lose the buds for the following spring every 2 or 3 years. I don't think the temperatures have dipped that low in those areas in years.

    Annie at the Transplantable Rose

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