Post #62 Breaking News About Climate Zone Changes
Post Description: Did you hear the USDA has changed our hardiness zone? How is this determined, and what does it mean for us? This post will explain.
Big news broke recently! If you live in South Florida you may have heard, we are now in zone 11a! Gone is the zone 10 status we have been planning our gardens around since 2012.
The USDA’s Agricultural Research Service, working in conjunction with Oregon State University’s PRISM Climate Group, have released a new plant hardiness climate zone map.
If you are already an avid gardener, or a watch-dog of climate change, this is a big deal, right? If you are newer to gardening, you may recall the basic zone planting guides on the back of your seed packets.
Just as we wait for the Farmer’s Almanac to be released each year, we refer heavily to the climate zone map when creating a new garden space or reinvigorating our perennials each season. Up North it informs folks on what plants need to be protected from frost, down here in South Florida, it informs us on what variety of tomatoes can take our humid heat and when to plant to ensure the harvest before hurricane season!
Although the USDA is hesitant to correlate the changing zone map to climate change, we encourage you to take a look at the trends and come to your own conclusions.
The last zone map change was rolled out in 2012, and at that time 2 new zones were added, zones 12 and 13, to accommodate the warming climate. The 2023 zone map puts most of the zones in the United States at about 2.5 degrees warmer than the 2012 map. This means that at least half of the country has been updated to a warmer zone.
So How is the Map Created?
Based on data from 13,625 temperature stations, the 2023 zone map was created using the newest version of PRISM, a climate mapping technology created at Oregon State University.
There have been several renditions of the map over the years, each one increasing in accuracy and complexity with the rise of technological intelligence. Historically, the zone map data consisted of the coldest night of the year in each zone. Over time, more data points have been incorporated to account for elevation, coastal effects, and more.
The current map was reviewed by horticultural experts, climatologists, and agricultural meteorologists before being finalized and presented to the public.
The 2023 map is a GIS model of the United States showing the geographic range of climate designed specifically for internet use. You can pinpoint your exact micro-climate zone information by entering your zip code, very cool!
What This Means For Us
Well there are two sides of the coin here. Yay, we can grow more tropical varieties in our newly zone 11a climate! Eek, the earth’s atmosphere is warming at an alarming rate…
Given that this is a garden blog focused on sustainability and beauty, we’ll revel in the former while keeping an awareness regarding the latter.
So, what can we plant now?! This new climate zone allows for a greater variety of tropical perennials, both ornamental and edible.
We have a dear friend who planted a breadfruit tree here in South Florida a few years back when most of us thought it would never fruit in zone 10. It now has had several years worth of prolific production, and he is reaping the rewards.
Try some new varieties!
Local nurseries can point the way, since they have been dealing with the gradual increase in heat for many years. But do not overlook greenhouse suppliers who deal in rare tropical plants. As with breadfruit, many of these were actually too tropical for our zone, but may work here now. Embrace the silver lining!
This warmer climate shift also means we need to take care with some varieties that used to do well in our Zone 10 climate but can’t stand the heat being cranked up much more. Zone 11a affects our ability to grow more temperate varieties of annuals and some perennials as well.
Pro Tip: On the coat-tails of a zone map change, look to the internet or local gardening groups for varieties that grow well in our new zone, not the back of the seed packets which may not be updated for 2024. Even many websites of nurseries may not be updated yet, but that’s ok. Just start searching them for Zone 11 instead of 10, and the right plants should show up, since our climate is that hot now.
Stop by for more information on what we can grow (and what annual edible varieties we should swap out) in our new zone 11a. We put out a new blog every Tuesday. Sometimes we’ll run a series, sometimes we’ll do plant profiles, other times we just get down and dirty about growing beautiful AND functional forest gardens in our new zone 11a!
Let me know what you are up to in your little corner of paradise. Have you experimented with new, warmer climate plants recently? How did it turn out? Are you still considering new varieties? Have a story to share or burning questions to ask?
Reach out and let me know. I always love hearing from you!
Happy gardening,
Mary