Kilbourn Park is doubling down on native plants for this year’s Mother’s Day sale

This coverage is made possible through a partnership between WBEZ and Grist, a nonprofit environmental media organization.

Renee Costanzo cranked on the rusty pulley with both hands, watching the greenhouse roof creak open in sections. A breeze of spring air swept over 12,000 seedlings lined up in plastic trays in the Kilbourn Park greenhouse.

Costanzo, the Chicago Park District’s only full-time employee at the northside greenhouse, spearheads a months-long effort to grow more than 15,000 plants including vegetables, greens, and flowers that will be ready in time for the 30th annual Kilbourn Park plant sale this weekend.

The massively popular sale draws upwards of 1,100 people every year, with local gardeners lining up around the park waiting to snatch up plants at $4 a piece.

“We generally start these annuals at the end of February,” said Costanzo, pointing to rows of popular annual flowers like zinnias, marigolds, and geraniums, which provide bright blooms all summer long before dying at the end of the season. "So we've been coddling and loving these babies for months now, and we just want to get them into happy homes.”

For decades, Chicago gardeners flocked to the Kilbourn Park sale to pick up tomatoes, cucumbers, and some annuals — the standard starter kit for backyard gardeners. But this year, the park responded to a relatively new demand: Nearly 1 in 5 plants for sale are native plant species that have adapted to local climate and wildlife and are generally low maintenance.

“Just in the last five years, people have asked for more natives, which is why we've been increasing our production,” Costanzo, who experimented with 30 different native species back in November ahead of the plant sale this year, said.

Other local plant sales across Chicago and the country are incorporating native species at a pace surprising to even veteran horticulturalists who remember a time when they couldn’t give them away.

That relatively new mainstream demand has been driven, in part, due to concerns about dramatic declines in insect species. The caterpillars of the Monarch Butterfly, for example, depend on native milkweed as a food source. Even backyard gardeners are also facing looming concerns about climate change-powered extreme heat, drought, and flooding.

"Native plants have been adapting to change for thousands of years,” said Tiffany Jones, who leads habitat education throughout the Great Lakes region for the National Wildlife Federation. “They need less water, less maintenance, and they're incredibly resilient — not to mention they help flood prevention with their deep root systems and provide habitat for all kinds of crucial species and pollinators. They're practical and beautiful."

For a long time, native plants were seen as little more than weeds, but their value has grown significantly.

“I've watched this for 44 years, from almost zero to now,” said Neil Diboll, the president of Prairie Nursery, a Wisconsin-based nursery which grows and ships native plants across the country.

“It's not a fad,” Diboll said. “This is a long, steady climb.”

Last year, Diboll said his nursery experienced a 7% increase in plant sales. This year, they’re shipping out about 500,000 native plants and even more seeds. Back in 1982, when Diboll first started selling plants, business was tougher: The company grossed just over $13,000 dollars. These days, he said, “you can add a few zeros on there.”

Still, he said that a drive through any American suburb will quickly reveal that the green turf lawn still reigns supreme. “So, it's just getting started,” Diboll added.

As the native plant business continues to grow, the annual Kilbourn Park plant sale is hoping to help meet some of that demand. To make it happen, it means a team of local volunteers coming out on a weekly basis to help sort, pot, and move seedlings.

“It's going to be down to 30-something tonight, so everything has to go in, and then the next day everything comes out,” said Lourdes Valenzuela, a retired schoolteacher who has volunteered at the north side plant sale for 12 years. “But it's completely worth it.”

Valenzuela is part of the Friends of Kilbourn Park Greenhouse, a dedicated group of local volunteers that work to raise funds that help expand resources for the nursery. With help from funds collected at previous plant sales, they’ve been able to buy benches, a shed and even a patio — increasing the footprint of the educational center.

“This year, we're looking a little bit bigger,” Valenzuela said. The goal is to raise $25,000, about half of the total projected cost, for a new outdoor learning center. The hope, in part, is that the surge in enthusiasm for more ecologically grounded gardening also helps power fundraising.

“We're not fighting against the climate here. We're working with it, and because it's what's native to this area,” Valenzuela said. “And they're beautiful.”

Kilbourn Park's annual plant sale will run from 9 a.m. to 1 p.m. on Saturday and Sunday.