Southeast Louisiana gets new planting zones in USDA hardiness map
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Gardeners in southeast Louisiana can successfully grow more tropical plants due to warming temperatures, according to a U.S. Department of Agriculture map released last month.
Why it matters: The Plant Hardiness Zone Map is a kind of bible for farmers and gardeners, helping them understand which plants can thrive in their area — and when to plant them.
- It's the first hardiness map published in more than a decade.
- The new zones are particularly significant for those already growing plants at the extreme edge of their suggested range.
Driving the news: Much of southeast Louisiana moved into warmer zones in the new map.
- The North Shore is now in 9a, and the south shore is 9b. Previously, they were a mix of 9a, 9b and 8b. Plants that thrive in higher number zones are less cold tolerant.
- Boothville and other places at the extreme tip of Louisiana are now 10a, same as parts of south Florida, Texas and California.
Catch up quick: The map was last published in 2012, based on 30 years of average annual low temperatures between 1976 and 2005.
- The new map — showing the coldest average temperatures have crept up about 2.5°F across the U.S. — taps data from 1991 to 2020 and information collected from more 13,000 weather stations, writes Axios' Emily Harris.
- That's nearly double the data collection points compared to the previous map — improving the accuracy of the new one.
How it works: The map divides the U.S. into 13 zones, each representing a range of 10°F.
- Each zone is divided further into two 5-degree half zones.
- The map also takes into account factors like elevation, wind exposure and proximity to large bodies of water, says Heather Kirk-Ballard, a horticulturist with the LSU Ag Center.
Yes, but: Many factors influence whether a given plant grows successfully or not, including light, soil moisture, humidity and exposure to the elements.
- The USDA recommends consulting with local producers, nurseries and master gardeners for area-specific growing advice.
The bottom line: You don't need to start changing which plants you're growing — thriving plants will likely continue to grow successfully.
Go deeper: Growing guide from LSU AgCenter.