The growing season is fast approaching, and this year, many gardeners have a new worry: how to attract pollinators to their gardens without poisoning them in the process.

It's a complex and controversial topic that caught fire last summer after the release of a study claiming that many plants sold at garden centers, even so-called "bee-friendly" plants, had been pre-treated with neonicotinoids, a widely used class of pesticides that some believe is a factor in bee die-offs or colony collapse disorder.

Many home gardeners had never heard of the "n" word before last year.

"One woman called me, crying, because her whole hedge, that she'd planted in part for pollinators, came from a company that uses neonics," said Paige Pelini, co-owner of Mother Earth Gardens in Minneapolis, which recently hosted a seminar on the topic. "I'm glad people are worked up about it," she said, although she doesn't want gardeners to panic and overreact.

Neonicotinoids' role in bee decline, as well as how long the pesticide remains active and toxic, is unknown and being studied. However, some garden retailers are already taking action. Minneapolis-based Bachman's recently announced that it had removed products containing neonicotinoids from its store shelves, and was eliminating the use of neonicotinoids in its nursery stock and outdoor plants at its growing range in Lakeville.

"It was not an easy decision," said John Daniels, vice president of production and wholesale. "We spent all winter talking about it." He noted that other factors are suspected in bee decline, including loss of habitat. "This is a fast-moving story, and the story is way ahead of the science," Daniels said. Still, Bachman's received many calls from concerned gardeners and decided to take precautionary action. "We're taking it very seriously. Everybody is."

That's not to say that every plant sold at Bachman's this growing season will be neonicotinoid-free, Daniels cautioned. Bachman's-grown plants will be not treated with that class of pesticides, but plants from other growers may have been. Bachman's is currently surveying its growers and training sales associates on the issue, so that they can direct concerned customers to plants that have not been treated, Daniels said. Bachman's-grown plants also will be identified in their labeling.

Bachman's decision was "exciting news" to Lex Horan, Minneapolis-based organizer for the Pesticide Action Network North America.

"Bachman's is doing exactly what we'd like to see from garden stores across the country," he said. "They've stepped up to eliminate neonics from their supply chain, with refreshing transparency about their process. Smaller garden stores are doing the same thing. Now it's up to the biggest players in the market: Home Depot and Lowe's. … Action from these two major companies will shift the whole supply chain in the right direction, making it much easier for small and midsize local stores to source neonic-free plants."

Use of neonicotinoids is much more widespread than most people realize, according to Pelini. Mother Earth Gardens is not a grower, so it must work with its vendors to avoid the use of synthetic pesticides. Last year, Mother Earth contacted growers to seek further information, and stopped purchasing perennials from one local grower who could not assure them that plants were not being treated. All of Mother Earth's current suppliers for seeds, vegetables and herbs are 100 percent organically grown, and annuals and perennials are 90 percent organically grown, according to Pelini. But sourcing organically grown trees and shrubs has proven to be a much bigger challenge, she said. Because of the length of time and financial commitment it takes to grow large plants, and the distance they're often shipped, pesticide use remains the industry standard.

Local garden experts are quickly trying to educate themselves on the topic. "I'm not an organic chemist," said Lewis Gerten, part owner and general manager of greenhouse production for Gertens, based in Inver Grove Heights. "We have to refer back to the EPA." But in the meantime, Gertens, too, has decided to err on the side of caution, eliminating the use of neonicotinoids on bedding-plant crops. Vegetables and "flower-garden plants, like marigolds, impatiens and petunias" sold at Gertens this year will be neonicotinoid-free, Gerten said. "But if you're picking up a tropical plant from Florida, we won't be able to tell you. It's a big world in horticulture, and I can't speak for all vendors. The whole industry is adjusting very quickly. It was probably a good wake-up call."

Gardeners who are concerned about neonicotinoid use can do several things, according to Pelini. "We can propagate. We can grow from seed. And buy from somebody you trust, who uses organic growing methods." The younger and smaller the plant and the more local the source, the less likely the plant has been treated, she said. Mother Earth is encouraging its customers to "keep talking about it, to everyone, to stop the chemical path as early as we can, and do no more harm. If we want to see change, we as consumers have to have different expectations."

Neonicotinoids became the industry standard because they're effective at controlling pests, Daniels said. They're widely used in treatment for Japanese beetles and emerald ash borers, for example. "To choose not to use it is giving up our best weapon," he said. Gardeners who want to avoid neonicotinoids may have to be prepared to accept more insects — and more insect damage. "It's a little scary from a producer's perspective."

Kim Palmer • 612-673-4784