It’s always something. It could be flea beetles on the broccoli. Or blossom end rot on the tomatoes. Or powdery mildew blanketing the pumpkin patch. (Maybe all of the above!) Gardeners have long taken these—and plenty of other—challenges in stride.
But, with increased temperatures and more frequent and extreme weather events, gardeners everywhere are facing some altogether new challenges.
Even the tried-and-true U.S. Department of Agriculture’s Plant Hardiness Zone map has gotten out of whack. After examining data from 5,000 National Climatic Data Center cooperative stations throughout the U.S., the Arbor Day Foundation released a new Plant Zone Hardiness map in 2015. Originally based on the USDA’s 1990 Plant Hardiness Zone map, the new version revealed that many of the country’s climate zones have moved.
Of course, some shifting over a period of decades isn’t unusual. But as for these changes? “It’s very difficult for farmers to react to climate right now, because the pace that it is happening is so much faster than what people had anticipated. It’s happening really quickly,” says Fan-Li Chou.
Chou is vice president of scientific affairs and policy for the American Seed Trade Association, which includes conventional GM seed purveyors, as well as organic, conservation and wildflower seed companies, among others.
And, ready or not, growing conditions are expected to continue to change. “As far as temperatures go, over the shorter term—say the next 20 or 30 years—the scientific consensus … is that the average temperatures are going to continue to rise,” says David Hollinger, director of the USDA’s Northeast Regional Climate Hub.
What’s more, Hollinger notes, “In a lot of places over the last few years, warmer wintertime temperatures and very early springs are causing plants to start breaking dormancy early. But the timing of the freezes and the cold snaps hasn’t changed as much. So you are having plants becoming more vulnerable and getting damaged by the normal springtime cold or frost, because they’re losing that dormancy.”
Location, Location, Location
No matter where you garden, you already may have noticed some crops are trickier to grow than they used to be.
“This whole thing is pretty complex, because climate change has different effects in different regions,” says Jim Myers, a professor of vegetable breeding and genetics at Oregon State University. “It might be a longer season or higher temperatures or more extremes—more rainfall or humongous storms in certain areas. Those require different adaptations in different crops.”
According to climate scientist Richard Seager, a Palisades Geophysical Institute/Lamont research professor at Columbia University, the West Coast’s historically warm, dry Mediterranean climate is heading northward. The east coast’s subtropical climate is also shifting north of the coast.
“The more subarctic climates in eastern Canada are moving northward as well,” Seager says.
“There are also going to be shifts in precipitation,” he says. “Much of the United States is projected to receive more precipitation with the exception of the Southwest, which is expected to get drier. So, wherever your garden is, you can be thinking about plants that [do] better in a warmer climate.
“If you are in New Jersey, you might think the plants that will be growing well there in the coming decade or two might be ones that currently are more suited to growing in Virginia, for example.”
New Seed Solutions
Plant breeders are combining new technologies with time-tested practices to develop staple crop varieties that can better withstand the current—and continued—climate changes.
“What the breeders are trying to catch up with is, ‘How do you develop a new variety that can be grown where you’ve always grown it—even under new climate conditions?’” Chou says.
“There are a lot of people working on drought-resistant wheat and drought-resistant rice, because those are the major food crops. But I think fruits and vegetables are much harder. In the U.S. right now, many of the plant breeders are working on how to grow more vegetables [that require] less water.”
Often, such vegetable- and fruit-breeding programs operate under the auspices of public sector universities.
“One thing that large seed companies do, in particular, is breed for broad adaptation,” Myers says. “They’re not trying to adapt to specific regions necessarily.… That’s where some small breeding programs can have an advantage, if they’re targeting these regional adaptations.”
Focusing on such regional needs, Allen Van Deynze works at the University of California, Davis’s College of Agricultural and Environmental Sciences as director of research at the Seed Biotechnology Center.
“[Plant breeders] look for stuff in places where you think [environmental] stress might be,” he says. “For example, we do a lot of breeding for resistance to disease, so that we don’t have to control it in another way. We always try to find plants growing in areas where that disease is prominent.
“And we hope to find those that are resistant and then put those in varieties that would be locally adapted.”
“The difficulty in plant breeding is that it takes so long to get to a variety that you can actually put in a seed packet to sell to a home gardener or even to a major producer,” Chou says. “It takes 10-plus years to get there.”
Adapt & Overcome
Just what’s a gardener to do in the meantime? “Everything is changing so much that it’s a good idea to have a number of different varieties in the field just to make sure that you capture something this year that is going to work well,” Van Deynze says.
“And what works well this year may not be what worked well last year.”
Besides planting many different varieties of a particular crop, don’t be afraid to wander outside of your historic plant hardiness zone. Consider several new-to-you vegetable varieties that usually would flourish to the south or southwest of your current location.
You might also contact any nearby universities or seed companies to determine whether they’ve recently bred specific crop varieties that might thrive in your area. And, when searching online for new seeds to consider, use multiple keywords, including “climate-resistant,” “climate-resilient,” “drought-tolerant,” “heat-tolerant,” “flooding-tolerant,” “stable” and “robust.”
You might also look for organic seed varieties.
“In organic environments, the inputs and the conditions that they are grown under are often quite variable,” Myers says. “Varieties that do best in organic systems are those that have a lot of environmental buffering. In general terms, [these] varieties … might be a little more stable and productive for growers.
“There aren’t a lot of varieties like that out there. But there are starting to be some in some catalogs that work in this area.”
Seed Success Stories
In some cases, breeders have already developed more heat- and drought-tolerant veggies—largely for use in the southern and southwestern U.S.
“I know the breeder who developed a snap bean variety called Sahara,” Myers says. “He did it by selecting under extreme heat conditions down in Texas. That’s a variety that I’ve seen be a very stable performer over the years.”
As for strong broccoli contenders? “Arcadia is a hybrid that’s probably 20 or 30 years old,” Myers says, “and it’s very stable. Sakata has a broccoli hybrid called Eastern Crown which they bred specifically for the East Coast, and it seems to be pretty robust.”
Myers also mentioned the work of his predecessor, Jim Baggett. Hoping to develop tomatoes well suited to western Oregon’s cold springs and summers, Baggett combined early bush habit tomatoes with seedless tomato varieties. The result was several tomato varieties, such as Gold Nugget, Siletz, Santiam, Legend, and Oregon Spring that will set fruit in cold conditions.
But that’s not all.
“It’s interesting, because not only do these tomatoes set fruit under cool temperatures, but they also set fruit under extreme heat,” Myers says. “I used to get someone once a year contacting me from Phoenix, Arizona, saying Oregon Spring was the only tomato that would set fruit throughout the summer in Phoenix.”
“Those are examples of traits that can be used to extend the range of a crop when the climate is throwing things at you that are too extreme for a normal variety,” Myers says.
Despite the climate complexities ahead, Hollinger remains optimistic. He’s sure there’s a solution to plant hardiness zone challenges.
“There have been lots of other environmental problems that people have basically solved,” he says. “Whether it’s acid rain or it’s the ozone hole, DDT, leaded gasoline. All of these things, once upon a time, were really serious problems. And all of those are measurably better now….
“I think we can be confident that we can do that with climate. It’s probably the biggest issue that any of us have to face, so it may be more difficult. But it’s not impossible.”
Chou is optimistic, too. “Think about Kansas and the Dust Bowl,” she says. “We developed a variety of wheat that can grow there. There is so, so much science—and investment in science—and knowledge in a teeny, tiny little seed.
“That, to me, is super powerful.”
This article originally appeared in the January/February 2021 issue of Hobby Farms magazine.