Climate change & growing zones

by Caroline Brown

2006 in many ways was the year of recognition that global climate change is not a liberal fantasy. Thanks in no small measure to Al Gore’s An Inconvenient Truth and to incontrovertible evidence that the Earth is changing, it became harder and harder to deny the reality of climate change. This was the year that global warming deniers changed their tactic from “it can’t be proved” to “maybe it’s not such a bad thing after all” and “we don’t know exactly what’s causing it.” Ah, progress.

I promise there’s a gardening angle below the fold…

Most of the government agencies whose charge is to research climate change and develop and implement policy in this area (for ex., FWS, USDA, NOAA, NASA, EPA, etc.) have been looking away for the last six years, addressing the situation only with weasel words and ambivalent, meaningless declarations. Appointed by Bush to do his bidding, most of these agency’s administrators squelch any respectable science and research that their scientists might be producing. (Remember Dr. Hansen from NASA? who was being silenced by a 24-year-old NASA employee, a former Bush campaign worker and college dropout with no scientific background?) Agency scientists must walk a fine line between doing their jobs and making their commander in chief look like a moron for refusing to mandate his oil and gas company buddies to take reasonable steps to decrease such an obvious threat as global climate change.

The USDA (Dep’t of Agriculture) is important to gardeners and farmers for many reasons, not least of which is that it creates and maintains the USDA Plant Hardiness Zone Map. Your growing zone (I’m in 6a) and its accompanying average annual minimum temperature (-5 to -10 degrees F in 6a) determine what plants are hardy in your area (notwithstanding the vagaries of microclimates). In other words, Zone 9 plants likely won’t survive in Zone 6 climates.

Or will they? The USDA’s map was last updated in 1990, and the agency is supposedly working on a revision. Will the revised map reflect the reality of climate change? And will it mean that I can grow avocados in Rhode Island after all?

The National Arbor Day Foundation got tired of waiting. They figured they could analyze data just as well as the government, so they took a look at 15 years of climate data gathered by NOAA (National Oceanic and Atmospheric Administration) research stations across the US. The result is a NEW HARDINESS ZONE MAP!!

You have to check this out. In addition to the new map, they provide lots of cool comparative data, including a map that shows how zones changed in relationship to the 1990 USDA map, and there’s even a nifty animation that very effectively illustrates what has changed. You can also search for your growing zone by zip code.

As for climate change, the organization’s press release notes that:

The new map reflects that many areas have become warmer since 1990 when the last USDA hardiness zone map was published. Significant portions of many states have shifted at least one full hardiness zone. Much of Illinois, Indiana, and Ohio, for example, have shifted from Zone 5 to a warmer Zone 6. Some areas around the country have even warmed two full zones. (emphasis mine)


The new 2006 Hardiness Zone Map is consistent with the consensus of climate scientists that global warming is underway. Tree planting is among the positive actions that people can take to reverse the trend.

My corner of Rhode Island doesn’t look to have changed any, though a small coastal area has changed from Zone 6 to Zone 7. Nearby Cape Cod and the islands of Martha’s Vineyard and Nantucket have increased from Zone 5 to Zone 7!

I don’t know whether to plant an avocado tree, or cry.

As for the USDA’s Hardiness Zone Map, no word on when its revision will be completed or whether it will show that US climate is indeed changing. If it does, how will BushCo continue to defend its stance against regulating climate change?

No doubt with more weasel words. Last week, the Department of the Interior moved to place the polar bear on the endangered species list, because its habitat (ice) is slowly disappearing. Hmmm, wouldn’t that seem to imply that global climate change is a threat? No, not exactly, according to the agency’s chief:

But in a conference call with reporters, Interior Secretary Dirk Kempthorne said that although his decision to seek protection for polar bears acknowledged the melting of the Arctic ice, his department was not taking a position on why the ice was melting or what to do about it.

On second thought, forget the avocado tree. I’ll plant some red maple seedlings, and pray.


Image courtesy of the National Arbor Day Foundation.


5 Responses to “Climate change & growing zones”

  1. Maybe it’s the answer to feeding more people. With longer seasons, we could grow more food. I mean wouldn’t it be great if Alaskan farmer’s could grow corn in October? Shouldn’t we just dump CO2 in St. Petersburg and grow our GM soybean out of Russia to support the demand for global hunger?

    But really, I’m not a fan of Al Gore, but yeah I think pollution is scary and it’s crappy the way we view the world now as our resource not our home. I mean I love biking, but without a cold winter to not bike I feel like I should bike year round- something that would easily cause knee problems. Similarly, most farmer’s on the east coast enjoy their two months off and cannot imagine working year round like west coast farmers.

    Although, I’ve always wanted a banana farm in Maryland.

  2. Thing is Matt, as much as I would love to be able to grow Doyenne du Comice pears in NW England, I also know that by the time I can do so, many people in Africa will have died due to seasonal rainfall not happening on schedule and rising temperatures.

  3. Oh I know I’m with you. The comments about Alaska where sarcastic and “tongue in cheek.”

    Sorry about the confustion. I’m perfectly fine with getting an avocado now and then from California and I love having season here in the mid-atlantic.

  4. Conservation Leaders Ask –Will Maple Syrup, Christmas Trees, Fall Foliage Season, and Other New England Icons Fall Victim to Climate Change?

    Framingham, Massachusetts – Maple/beech/birch and spruce-fir forest types are very likely to be completely displaced by more southern forest types by the end of the 21st century in New England. The disappearance of these regional icons, and the tourism, products, and ecological communities that depend on them, are considered in New England Wild Flower Society’s new POLICY ON CLIMATE CHANGE, the group announced today. The Society is America’s oldest plant conservation institution and the leader in New England plant conservation. The Society’s comprehensive initial review incorporates research of multiple groups, including the Intergovernmental Panel on Climate Change (IPCC). To download a free copy of the policy, visit
    “Climate change is a complex and serious plant conservation issue with a profound impact on plants and ecosystems,” said Gwen Stauffer, New England Wild Flower Society’s Executive Director. “This initial policy sets a course of action for our own organization and a large network of collaborators, as it begins to frame our response.”
    “The native flora concept will change as native plants from the south move northward into new regions,” said Bill Brumback, Conservation Director of New England Wild Flower Society. “This initial policy represents a sea change in how we will look at plant conservation in the future. Up until now, plant conservation strategy began with the land—studying it, protecting it, and managing it. Now, we will review our concept of what actually constitutes a natural community in our region, and adapt conservation efforts to the best scientific rationales, as these comprehensive changes take place.”
    The Policy includes plans for collaboration with multiple scientific groups to develop strategies to respond to the complex challenges of climate changes and OVER> effects on plant health and natural ecosystems in New England. Important ecological shifts include the possible elimination of most regional bog ecosystems, the likely extirpation of multiple northern forests, and the increase of invasive plant activity. New invaders to our area, formerly not species of concern because of their lack of hardiness in our climate, such as kudzu, are likely to take greater hold because of their competitive advantage. The Society is committed to an “early detection—early response” action through its conservation programs and collaborative actions, such as the Invasive Plant Atlas of New England (IPANE) and the Plant Conservation Volunteer program (PCV) The PCV program has garnered international recognition and next week represents New England at the Global Botanic Gardens Congress, in Wuhan, China. The Society’s delegate, Ailene Kane, will be sharing the PCV model and plant conservation training with conservation leaders from other countries around the world.
    The Society began stepping up related initiatives over the past few years. In 2006 it joined the Seeds of Success program as the Northeast leader in a U.S. – led effort that is part of the Millennium Seed Bank project initiated by Royal Botanic Garden in Kew, U. K. The project’s goal is to collect and bank seed for 10 percent of the flora in the northeastern U.S., thereby creating an insurance policy against ecological loss or damage to the bioregions of the Northeast. New England Wild Flower Society recently completed a design for a Native Plant Center at its Nasami Farm Native Plant Nursery location in Whately, Massachusetts. In addition to its role in supplying native plants for gardens and restoration, the proposed Center will be used for seed bank work, as an educational resource, and, eventually, to supply native plant material for “green corridors,” as a response to the fragmentation of our green spaces. The Center is designed to meet the LEED Gold standard for sustainable design and construction. Says Director Stauffer, “For all of us, lightening our footprint on the land is an important part of our response to climate change.” The building is expected to be one of the first 200 in the United States to receive this designation from the U.S. Green Building Council.
    The Society’s new publication, Invaders…We’re Fighting Back, a resource for updates and plant identification, is available by calling 508-877-7630, ext. 3601, or online at or at the Museum Store at New England Wild Flower Society’s Garden in the Woods headquarters, 180 Hemenway Road, Framingham, MA.


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