The reality of climate change should spark gardeners to both reduce their carbon footprints and adapt. With earlier springs, warmer summers, droughts and extreme weather events becoming the norm as climate shifts intensify, practicing sustainable gardening is more important than ever. To share how gardeners can have a positive impact on the environment while making their gardens more resilient, my guest this week is soil and plant ecologist Dr. David Wolfe.
David retired in 2021 from the Cornell College of Agriculture and Life Sciences School of Integrative Plant Science after 30-plus years as a faculty member at the university in Ithaca, New York. However, he may now be busier than ever. He serves as chair of the Cayuga Lake Watershed Network Board of Directors and as a member of the Conservation Advisory Council for the Town of Lansing in New York. His career and his post-career activities have focused on climate change adaptation and mitigation strategies for managed and natural ecosystems; soil health and water resource management; and soil carbon assessment. He’s also the author of “Tales From The Underground: A Natural History of Subterranean Life,” a 2001 book that still reverberates today.
Soil and plant ecologist Dr. David Wolfe retired in 2021 from the Cornell College of Agriculture and Life Sciences School of Integrative Plant Science after 30-plus years as a faculty member. (Photo Courtesy of David Wolfe)
David, who holds a Ph.D. from the University of California, Davis, in plant and soil ecology, has studied plants’ physiological response to environmental stress, their acclimation to elevated carbon dioxide levels, and spectroscopy and geostatistical methods for monitoring soil health and soil carbon change.
He’s worked to demonstrate how soil health and water management can be improved, including leading a $4.7 million National Institute of Food and Agriculture project to identify new tools for carbon, nitrogen and greenhouse gas management in agroecosystems and, from 2017 to 2021, serving as co-project leader for the state-funded New York Soil Health program. His fieldwork has brought him to East Africa for soil conservation and food security projects.
“I remember my first ecology class I took,” he says. “The professor said, ‘People asked me, what is ecology? And I tell them, it’s everything that’s interesting.’” David took that to heart.
David’s book “Tales From The Underground: A Natural History of Subterranean Life” is all about the soil beneath our feet and what lives in it.
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How Climate Change’s Impact on Plants Came to David Wolfe’s Attention
David joined the Cornell faculty in 1984 and says he was only there a few years when he first saw data on the rapid rise of carbon dioxide in the atmosphere, according to the Mauna Loa record.
“The impacts of climate change were not really widely apparent,” he said of that era. But the meteorological data was giving clues that something was really starting to hit the fan, he added. And he knew that the direct impacts of carbon dioxide would affect plants and their responses to stress. This led to David and many other scientists conducting experiments to determine how plants deal with stressors at the elevated CO2 levels that were expected to come.
Then during the Bill Clinton administration, there was the first effort to make national and regional climate assessments, he recalls. “So there was a Northeastern group that was going to look at what’s happening in the Northeast in particular in climate change. And it turned out that at that time I was really one of just a few scientists working on the potential impacts on agriculture and natural resources in the region
His work on climate policy mixed with his interest in water resources and soil management, though it wasn’t apparent to everyone how they intertwine.
“For a while, many people thought of me either as the climate change guy or the soils guy because I talked to different groups about the two different things, but now people are beginning to see how the two do blend because our soils can sequester a lot of carbon,” David says.
This led to David’s book “Tales From The Underground,” about the amazing discoveries in soil biology happening at that time. “I realized that the general public was not catching onto this, particularly farmers and gardeners who could really benefit from this information.,” he says.
And it wasn’t just about the disease organisms in the soil that kills plants but also about the “good guys” in soil, he points out.
The book has had a long life and has been translated into multiple languages, including an updated Spanish edition recently released. He says he thought the book would “run out of juice” after a while and become outdated, but that isn’t the case. “I read it now, and it’s still very relevant,” he says. “And my updated version I recently did, I just put in some new, more modern references.”
The chapters are like a tour through various cool things in the underground, he explains, and shares stories about the living organisms and the intriguing scientists who studied them. “It’s kind of like: Take my hand. I’m gonna show you this really cool habitat,” he says.
Dr. David Wolfe testifies at the U.S. Capitol. (Photo Courtesy of David Wolfe)
How CO2 Affects Food Crops
In David’s studies of food crops such as potatoes and beans, he found that elevated CO2 levels led to plants thriving vegetatively, but not actually becoming more productive.
David said one of the reasons he wanted to study elevated CO2 and its effects on plants is because many scientists and non-scientists were trying to counter concerns about climate change by pointing out that plants take up CO2 for photosynthesis to create sugars and grow. They hypothesized more CO2 in the atmosphere would lead to a greener, more wonderful world.
“I knew for a number of reasons, it wasn’t quite so simple as that,” David says. He found that the different types of stress that climate change afflicts on plants — such as extreme temperature exposure, prolonged drought and flooding — counters any benefit from the additional CO2.
For example, he grew potatoes and beans under optimal conditions and under conditions with occasional heat waves, with and without higher CO2 levels. He found that though the plants grew more leaves and branches when exposed to additional CO2, they did not produce more potatoes or more beans.
“The heat stress completely destroyed tuber production or aborted the bean flower pollination and bean production. So yes, you have bigger bean plants, but you couldn’t go to market with those,” he says.
At the same time, greater CO2 levels could be a boon for weeds. Some weeds have been found to become more resistant to herbicides in the presence of more CO2, which raises concerns about increased use of glyphosate and other chemical herbicides.
“It turns out that a lot of our most notorious and fast-growing weeds benefit the most from the high CO2,” David says. He also points out that earlier springs and warmer summers are leading to the proliferation of cold-blooded pest insects, which are spreading north.
One of the biggest factors in gardening for the future is being vigilant about tracking what’s happening south of you, he says. It might be coming your way soon.
“A knee-jerk adaptation to new pests would be put on more herbicides and insecticides,” David says, but he notes that what he communicates to farmers and gardeners is to think about strategies that don’t include more chemicals. He encourages practicing Integrated Pest Management and getting in touch with local gardening centers and cooperative extensions for advice and using mulches to smother weeds rather than herbicides.
The Future of Sustainable Gardening
We’re going to dig in — excuse the pun — on another one of David’s published works, “Gardening Sustainably with a Changing Climate,” a chapter that he contributed to the 2011 book “The New American Landscape: Leading Voices of the Future of Sustainable Gardening.”
David points out in the book that we’re the first generation of gardeners who can’t rely on historical weather records.
“Since early crop domestication, things have been pretty stable, and so you could look back on historical weather records or simply generation-to-generation comments on here’s what we do when,” he says. “But today — first generation that really can’t depend on that historical information to tell you what to plant, when to plant it or how to grow it.”
David recommends that gardeners adopt the same plan that agribusiness is working on: diversification. This includes staggering planting dates of your annuals and experimenting with crops that, historically, your region was too cool for.
“There’s nothing wrong with thinking about opportunities, and maybe your Aunt Mabel south of you was able to grow something and you’ve always wanted to try it. It’s not unreasonable to think about trying it — but it is risky because you can still go back to, quote, ‘normal weather’ in a year.”
In fact, many farmers have been diversifying this way while not realizing they were adapting to climate change, David says.
For hobby gardeners who grow food because they enjoy it and not because they depend on their gardens for their meals or their livelihood, there is a greater opportunity to experiment by planting crops earlier in the spring than usual or later in summer for a fall crop. It could work out and be really great, or it might not work out, but the cost is small.
David has led research and fieldwork to determine how continuing climate change will effect plants and soil in the future.(Photo Courtesy of David Wolfe)
From Too Little Rain to Too Much Rain
When David first started studying climate change, drought was the main concern — and that’s still the primary concern in the Southwest. But what’s happening worldwide is that when rain does come, it comes in bigger rainfall events than were historically typical.
Weather that switches from one extreme to the other forces growers to consider new irrigation plans as well as improved drainage. That includes amending soil with lots of organic matter, which helps with both water-holding capacity and the ability of soil to drain properly.
Though gardeners tend to be good about improving their soil, in commercial agriculture, soil is often degraded, David points out.
How Gardeners Can Reduce Their Carbon Footprints
The secret to doing more in the garden to help the environment is, in many ways, to do less. You can reduce your carbon footprint quite easily by using less fertilizer, particularly nitrogen fertilizer, David says. Nitrogen fertilizer, whether it is a synthetic product or something natural like manure, gives off nitrous oxide, a potent greenhouse gas. And the production of synthetic fertilizer also has a very large carbon footprint —two to five tons of CO2 emitted per ton of nitrogen fertilizer produced.
Lawns are notorious for their demand for nitrogen fertilizer, but you can reduce how much lawn you have by converting it to meadow and you can learn to tolerate your remaining lawn being a little less green at times. Let the soil microbes do the work of bringing nitrogen and other nutrients to the roots of the grass.
Mixing clover into your lawn is also a great way to naturally feed the lawn nitrogen. Clover is a type of legume, which fixes nitrogen in the soil, taking the nitrogen from the air. And in your vegetable garden, you can grow legumes in rotation with other crops to improve soil fertility.
Having less grass and more plant diversity will also attract a variety of beneficial insects, including bees and butterflies to entertain the kids — and the adults — and predatory insects that prey on pests.
Cornell’s Climate Change Garden
Cornell University has something really cool on its campus: the Climate Change Garden. It was designed by landscape architect Josh Cerra, who is an associate professor at Cornell, working with Sonja Skelly, the director of education at the Cornell Botanic Gardens. David has helped as a climate change adviser.
“The idea was really to give visitors to Cornell’s botanic gardens an experience, really almost to simply draw attention to the climate change issue and get people thinking about it with some educational materials, placards, etcetera within the space,” David says.
They don’t have the funding yet to build “the dream climate change garden,” he says, but for now and since 2014, there are several beds with different annual plants, some outdoors and some under a plastic greenhouse that can be modified to illustrate a heat wave.
One thing they’ve seen is that many weed species love the warmer temperatures, David says. They could also use the garden to show how extreme weather events and temperatures affect plants, such as a few days of heat resulting in crops dropping their flowers before they can be pollinated and produce fruit.
The team behind the Climate Change garden also has ambitions to do much more controlled experiments and play with CO2, David says. But what’s there now really does get the visitors who walk through thinking about climate change in their area and how to get involved in the public dialog.
The Cornell Climate Change Garden is giving people an opportunity to put themselves into the future before we’re actually there, observationally and tangibly, by seeing and feeling what it’s going to be like. It’s an important and valuable project.
A rendering of the Cornell Climate Change Garden, which illustrates how climate change affects plants, including food crops, weeds and more.
(Photo Courtesy of David Wolfe)
I hope you enjoyed my conversation with David Wolfe on gardening sustainably in the face of climate change. If you haven’t listened yet, you can do so now by scrolling to the top of the page and clicking the Play icon in the green bar under the page title.
How have you adapted your garden to climate change? Let us know in the comments below.
Links & Resources
Some product links in this guide are affiliate links. See full disclosure below.
Episode 128: Conserving Water’s Finite Supply in a Very Thirsty World
Episode 219: Troublesome Garden Pests: Organic Control Strategies That Work
Episode 238: Peat Moss: Examining the Challenges of Its Ongoing Use in the Face of Climate Change
joegardener Online Gardening Academy™: Popular courses on gardening fundamentals; managing pests, diseases & weeds; seed starting and more.
joegardener Online Gardening Academy Organic Vegetable Gardening: My new premium online course membership opens in 2023. Sign up for the waitlist here.
joegardener Online Gardening Academy Beginning Gardener Fundamentals: Essential principles to know to create a thriving garden.
joegardener Online Gardening Academy Growing Epic Tomatoes: Learn how to grow epic tomatoes with Joe Lamp’l and Craig LeHoullier.
joegardener Online Gardening Academy Master Pests, Diseases & Weeds: Learn the proactive steps to take to manage pests, diseases and weeds for a more successful garden with a lot less frustration. Just $47 for lifetime access!
joegardener Online Gardening Academy Perfect Soil Recipe Master Class: Learn how to create the perfect soil environment for thriving plants.
“Tales From The Underground: A Natural History Of Subterranean Life” by David Wolfe
“The New American Landscape: Leading Voices of the Future of Sustainable Gardening” edited by Thomas Christopher
David Wolfe, Cornell College of Agriculture and Life Sciences faculty profile
Gardening with a Mission | John MacLeod Lecture 2017 | Royal Horticultural Society
NOAA: Monthly Average Mauna Loa CO2
Greenhouse Megastore – Our podcast episode sponsor and Brand Partner of joegardener.com – Enter code JOEGARDENER for 10% off your order
Milorganite® – Our podcast episode sponsor and Brand Partner of joegardener.com
Disclosure: Some product links in this guide are affiliate links, which means we get a commission if you purchase. However, none of the prices of these resources have been increased to compensate us, and compensation is not an influencing factor on their inclusion here. The selection of all items featured in this post and podcast were based solely on merit and in no way influenced by any affiliate or financial incentive, or contractual relationship. At the time of this writing, Joe Lamp’l has professional relationships with the following companies who may have products included in this post and podcast: Rain Bird, Corona Tools, AeroGarden, Milorganite, Soil3, Greenhouse Megastore, PittMoss, Territorial Seed Company, Earth’s Ally, National Wildlife Federation and TerraThrive. These companies are either Brand Partners of joegardener.com and/or advertise on our website. However, we receive no additional compensation from the sales or promotion of their product through this guide. The inclusion of any products mentioned within this post is entirely independent and exclusive of any relationship.
