Three in four crop varieties have gone extinct. You can save the rest in your garden.

Here’s a way you can help protect the U.S. food system from pests, disease and climate change. All you have to do is plant a seed.

Each year, hundreds of American gardeners sign up for a citizen science program run by Seed Savers Exchange, a nonprofit that preserves thousands of heirloom crop varieties from around the United States. The Iowa-based group is looking for information about where these crop varieties will thrive — so gardeners volunteer to plant heritage seeds and send back data about how those plants grow and taste.

One day, that information could help scientists identify strains of tomatoes, eggplant, collard greens and other crops that are more resilient to droughts, freezes, invasive pests or changing growing conditions.

“Odds are we’ve got a variety that we’re holding onto that has the traits, the resistance, the tolerance, and that’s going to work well in your region under different climate pressures,” said Michael Washburn, preservation director at Seed Savers Exchange.

Why does biodiversity matter?

Seed Savers Exchange preserves more than 17,000 plant varieties — each of them adapted by generations of American farmers and gardeners to fit local growing conditions, tastes and farming practices.

Since 1900, farmers have abandoned three out of every four crop varieties in favor of a few standardized strains, according to the U.N. Food and Agriculture Organization. That raises the risk that changing climate conditions or a disease outbreak will cause widespread crop failures and hunger.

The mid-19th century Irish potato famine and the 1950s fungus outbreak that wiped out nearly all commercial banana production were the result of diseases that devastated just one or a few widespread varieties of each crop.

“Relying on just one banana species or just a few potato species has already been proven to be a bad move,” said Sarah Jones, a scientist at the Alliance of Bioversity International and the International Center for Tropical Agriculture (CIAT), a Rome-based nonprofit that studies ways to preserve diverse plant varieties.

About a century ago, governments, universities and farmers realized they needed to preserve many varieties of crops as an insurance policy against disasters, said Johannes Engels, an honorary research fellow at the Alliance of Bioversity International and CIAT. Seed Savers Exchange, founded in 1975, is one of about 1,750 “gene banks” around the world that collect and preserve seeds.

When crises hit, scientists dig through these seed archives to find crop varieties that can resist new pests, diseases or weather patterns, and breed them into new, resilient commercial crops.

In 2022, when a fungal infection was ravaging California celery crops, the U.S. Agricultural Research Service station in Salinas, Calif., tested heirloom celery varieties from Seed Savers Exchange’s collection to see if any could resist the disease. “Lo and behold, one variety called French Dinant showed strong resistance,” Washburn said.

Now, he said, researchers can crossbreed French Dinant celery with other varieties to create a disease-resistant crop.

“Diversifying is a way of countering risk,” said Karl Zimmerer, a Pennsylvania State University professor who studies global food systems. “Planting more types of crops means you’re not putting all your eggs in one basket.”

How to grow your own heirloom crops

To help Seed Savers Exchange collect information about how heirloom crops grow in different parts of the country, you can sign up for the nonprofit’s Adapt program. Washburn says gardeners at any skill level can participate, as long as they’re willing to send back data about how their crops are growing.

Registration is open now and runs until January. Later this year, Seed Savers Exchange will announce the types of crops it plans to test in 2025. Volunteers can choose which crop they want to grow, and in March, Seed Savers Exchange will send each participant free seeds from three varieties of their chosen crop. Volunteers are expected to grow the three varieties side by side and report information about how each variety grows, the yield each plant produces, how the crop tastes and how the plants hold up against pests and diseases.

“We get the information that comes back, and they get to eat really great food that they wouldn’t otherwise probably be tasting,” said Mike Bollinger, Seed Savers Exchange’s executive director.

This information will be critical for future scientists breeding crops that can handle new diseases and climates.

“It’s actually one of the best data resources, because it’s not scientists producing things in a very controlled environment where things are more likely to succeed,” said Jones. “It’s real-world fields where everything can go wrong, so it’s more realistic.”