There’s a lot of uncertainty in gardening. How will this variety of seeds work? Are the aphids — or the moose — going to kill my crop? Do I have enough fertilizer? Do I have too much fertilizer?
One constant that at least helps take the guesswork out of what you should grow, where and when, is the USDA Plant Hardiness Zone Map.
The zone map is the bible for deciding what types of plants to grow, based on their cold hardiness for your location.
But even that is changing. Though exact effects and timelines of climate change are difficult to predict, the overall trend in Alaska is clear — we’re warming up. Nancy Fresco, with the University of Alaska Fairbanks, is a network coordinator for SNAP — Scenarios Network for Alaska and Arctic Planning. She’s part of a team of climate researchers, farmers and gardeners puzzling out Alaska’s agricultural future.
The team created the Alaska Garden Helper, an interactive web-based modeling program that predicts changes in climate as they relate to agriculture for communities across the state. She gave a tour of the website during the Alaska Food Festival and Conference last week.
“These modeled results, I think, are really interesting for the broad story they tell about what might happen across many decades," Fresco said. "They’re not a management directive but they are a big-picture story about the future of what might be possible in Alaska.”
You can select a community and see projections for various factors.
“So, growing season is the number of days consecutively in the summer season when it’s above whatever threshold is selected,” Fresco said.
There are annual minimums, showing the coldest day for a particular date of the year. That’s important if you’re trying to grow something like fruit trees that can’t survive super cold winter temperatures. If you select Kenai, you see that Jan. 29 had its coldest temperature around -20 from 1980 to 2009. From 2010 to 2039, the coldest temperature on that date creeps up from -14 to -7. By 2070 to 2099, Jan. 29 is predicted to see coldest temperatures of 17 to 23 degrees above zero.
There are also growing degree days, which tell you how many days to expect above whatever temperature threshold you select.
And, of course, there are the zone hardiness maps, going back to 1980 and looking forward to 2099.
“The immediate story here is, ‘Wow that is an incredible change in color,’” Fresco said.
The western Kenai Peninsula was in zones 5b to 6a from 1980 to 2009, with annual extreme low temperatures of -15 to -5. From 2070 to 2099, the western peninsula is forecasted to be zones 8a to 8b, with minimum temperatures from 10 to 20 degrees.
“The projected shift out to the end of the century is a huge shift, up to about 1,500 growing-degree days above 50 (degrees) Fahrenheit," Fresco said. "That’s almost enough, maybe borderline enough, for these really warm crops, like sweet corn and tomatoes. Which, I don’t know about you, but it kind of blows my mind that in year 2100 you’d actually be growing outdoor tomatoes.”
It’s not just temperatures that determine which crops will be successful. Moisture conditions, microclimates and a lot of other variables factor in. But the garden helper at least helps growers start to plan for the future.
Alaska already struggles with food security, relying predominately on shipments from Outside. Becoming more self-sufficient in food production strengthens a community’s resiliency and helps avoid exacerbating climate change by cutting down on fossil fuel-dependent shipping.
“The reality is, if we’re going to mitigate climate change, growing local, being locally self-sufficient, is beneficial," Fresco said. "Not just because local food is better — is fresher, stimulates the local economy, gives people jobs, all the things that everyone here already knows — but it also burns less fossil fuels.”
Check out the Alaska Garden Helper on the SNAP website.
