Monday, January 30, 2012

New 2012 USDA Plant Hardiness Chart!

This could be confusing....  

I seemed to be operating on some really outdated information.... Based upon the 1990 USDA Plant Hardiness, I used to be in Zone 7b now I seem to be in 8a.  (No, I did not move again.)

Hmmm.... the old map had Fort Worth right along the edge of 7b and 8a.  So far I have noticed Fort Worth does tend to be on the colder side of the DFW area.  The summer seems to be warmer than Dallas (even warmer than New Braunfels) does this make the difference?

This website

For gardeners in Texas, this cute little website includes the old USDA zone and the new and contains lots of info including current drought condition, average first frost date, average first freeze date, number of days the temperature exceeds 86 degrees. (The map shading seems to be based on the old data however.)

Speaking of number of days above 86 degrees... "Plant Heat Zone Map" from the American Horticultural Society:

Probably the most important map for the gardener - especially the southern gardener.  Some plants can survive a few days at 86+ degrees but it is a totally different class of plant to make it 90 to 210 days.

O.K.  Now is a good time to cut and run.  More useless map info follows....

Regarding the USDA Hardiness map:  the new map (2012) uses data measured at weather stations during the 30-year period 1976-2005. In contrast, the 1990 map was based on temperature data from only a 13-year period of 1974-1986. (source

 If we have all this information, shouldn't we get a different average? Say 1960 - 2012?

Looking for more information I found many changes had actually been made back in 2006.  (You can actually see the changes with a fun graphic: ).

More historical maps:

1967 (source)

 1948 (source)

 1927 (source)

Still with me?  Need another map?
Sunset Magazine's climate zone map factors in length of growing season, timing and amount of rainfall, winter lows, summer highs, wind and humidity.   Created over 40 years ago for gardeners in the West and Southwestern US, the map has now been expanded to include the rest of the country.

Live in Canada?  Here is a map link for you!

1 comment:

Marguerite said...

Thanks for the Canadian link, I had wondered with the US map change if we had changed our stats at all. No changes at this point but it will be interesting to see what happens in future.