new usda plant hardiness zone map, with todd rounsaville

YOU NO DOUBT have seen news that the USDA Plant Hardiness Zone Map was just updated, and that half the country once again got reclassified a half-zone warmer just as many of us did after the previous update of the map in 2012. But what does it all mean to gardener’s practically speaking?

Todd Rounsaville is a USDA horticulturist and research scientist who was involved in the years-long project that led to the creation of the new map. He helped me drill into what it reveals and to other factors affecting plant hardiness.

Todd leads the U.S. National Arboretum Germplasm program, and he acted as chairman of the technical review team forthe 2023 USDA Plant Hardiness Zone Map, a group of about 40 people across the country.

Read along as you listen to the Dec. 11, 2023 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on Apple Podcasts (iTunes) or Spotify (and browse my archive of podcasts here).

2023 hardiness zone map, with todd rounsaville

Margaret Roach: Thanks for making time today, Todd, and it must feel good to see the multi-year effort come to fruition.

Todd Rounsaville: Thanks for having me. And yes, it’s nice to have this out and released to the public and very rewarding to see very positive comments coming in about both the utility of the map and also that gardeners are saying that it’s matched what they’ve seen in their landscape. That’s nice for that confirmation.

Margaret: I think reading some historical papers and so forth that you sent me to do a little homework before our conversation, I read I think that the first attempts that this kind of mapping were in like 1927, it’s a long tradition trying to figure out what’s going on out there[laughter].

Todd: