The Polar Vortex Portends … the Planting of Seeds?

Spring gardening stories are an opportunity for environmental reporters to address climate change, including through a look at recent shifts in plant hardiness zones. Above, an ‘Abraham Lincoln” tomato seedling. Photo: U.S. Department of Agriculture/Lance Cheung via Flickr Creative Commons (Public domain).

TipSheet: The Polar Vortex Portends … the Planting of Seeds?

By Joseph A. Davis

The temperature may still be dipping into frigid territory in much of the United States by the time you read this. Which means, if you are an environmental journalist, it’s probably time to write about the polar vortex.

But it’s also nearly spring. Which means, if some in your audience are gardeners, it’s time to write about ordering seeds.

It’s late, but not too late. It may be freezing, but they can start some things indoors.

Remind them that most seed companies will send them a free catalog. There are so many: what seed catalogs they get tells a lot about who they are.

For organic seed varieties, they can try Eden Brothers. For heirloom seeds, Renee’s or Johnny’s. For butterfly or pollinator gardens, they can look at Bentley. For native plant varieties, they can go to Ernst or similar regional catalogs.

There are other possibilities. And there’s nothing wrong with buying Burpee seeds at the hardware store. Any seed planted is better than no seed planted.

 

Keep this in mind for your reporting:

For gardeners, climate change

is always a local story.

 

Meanwhile, keep this in mind for your reporting: For gardeners, climate change is always a local story.

And for environmental journalists whose audiences love gardening, there’s “hot” news: the latest Plant Hardiness Zone Map. It can be used by home gardeners, commercial growers, farmers and ranchers.

 

What the map is — and isn’t

The map is produced by the U.S. Department of Agriculture’s Agricultural Research Service (the latest edition of which actually came out in late 2023, with the most recent previous updates in 2012 and 1990).

It’s based on “climate” as understood by weather statisticians, which is really the average from the latest 30-year period. As global climate changes because of human-caused emissions, things are generally getting warmer in continental North America.

For climate reporters, the headline is: The zones are shifting north.

 

What the Plant Hardiness Zone Map

specifically tells you is how cold the

low temperature gets in the winter.

 

What the map specifically tells you is how cold the low temperature gets in the winter. The zones are based on the 30-year average of the coldest temperatures of each year. Extreme frost, especially when prolonged, will kill many plants.

Note that the map is mainly relevant to perennials — the plants that survive over the winter to grow and bloom another year — not specifically to annuals, which include many of the vegetables and ornamental plants grown by home gardeners.

Technically, it does not tell you the average frost date as winter approaches or the average frost-free date as spring arrives. Both are hugely important to home gardeners of annuals. These are available via other maps and sources, including on Climate.gov and the Old Farmer’s Almanac.

But in practical terms, some seed companies base their recommended planting dates on the Plant Hardiness Zone Map, which is a handy substitute.

So as great as the Plant Hardiness Zone Map is, it will not tell you when to plant your tomatoes. That planting date can only be divined from ancient wisdom. Listen to the elders and watch your neighbors. But the short answer is: earlier — as early as you dare.

 

Story ideas

• Find the local garden club(s) and attend some meetings. (Pro Tip: Bring brownies.) Talk to them about what they plant and when. Listen when they complain about plants that have died over the winter.
• Talk to your local office of the National Weather Service (if it still exists). Ask about the coldest winters. Ask for data. Use this map to find them (or, if the map isn’t working, then this PDF).
• Go to local nurseries and talk to them. Go at different times of the year and ask what is appropriate to plant.
• Find national garden groups that focus on particular plants or kinds of plants. An example would be the Azalea Society of America. Visit their websites and talk to them about hardy varieties.
• Find some larger professional landscaping companies, especially ones that contract to plant at newly built homes. Talk to their experts about what plants are hardy in your area.

 

Reporting resources

• Local nurseries: These businesses sell living plants to gardeners. You can find many in the phone directory. Visit the site and talk to senior staff.
• Cooperative extension: This network of advisers can be found in most states and many counties. Based on USDA and land grant universities. See this directory.
• Community gardens: Many communities have sites where individual gardeners can get allotments. Visit them during gardening season and talk to veteran gardeners.
• Master gardeners: Many local organizations train and certify “master gardeners” who spend time advising gardeners. Start by asking at your nearest cooperative extension.
• Canada’s Plant Hardiness Zone Map: Natural Resources Canada has developed its own hardiness zone map for Canada.

[Editor’s Note: For more on this and related topics, see our Food System Topics on the Beat page.]

Joseph A. Davis is a freelance writer/editor in Washington, D.C. who has been writing about the environment since 1976. He writes SEJournal Online's TipSheet, Reporter's Toolbox and Issue Backgrounder, and curates SEJ's weekday news headlines service EJToday and @EJTodayNews. Davis also directs SEJ's Freedom of Information Project and writes the WatchDog opinion column.

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* From the weekly news magazine SEJournal Online, Vol. 10, No. 10. Content from each new issue of SEJournal Online is available to the public via the SEJournal Online main page. Subscribe to the e-newsletter here. And see past issues of the SEJournal archived here.