Neonicotinoids on My Seeds and Plants: How Dangerous Are They?

Updated: May 18, 2024

The flowers you plant could be doing more harm than good to pollinators. Here how to keep neonicotinoids out of your garden.

Many gardeners unknowingly plant seeds and seedlings and use lawn and garden products that harm birds and pollinators, according to numerous research studies and academic assessments.

Those studies, including a major one funded by the pesticide industry, show that pesticides called neonicotinoids (aka neonics) are a leading cause of bee and pollinator die-offs. Neonics are widely available to consumer gardeners.

“It is highly likely that plants and seeds you buy at big box and chain garden centers have most likely been exposed to neonicotinoids at some point in their production,” says Mary Phillips, head of the Garden for Wildlife and Certified Wildlife Habitat programs at the National Wildlife Federation.

Ornamental flowers and bushes are common culprits. But also a large number of native plants, like commercial milkweeds, contain neonics.

“With milkweeds, the host plant for monarchs, this is a huge problem,” says Heather Andrews, aka the Thoughtful Gardener. ” I am thrilled that growers are offering more native plants than ever before, but frustratingly, a recent study showed 33 of 33 commercial milkweeds were contaminated with pesticide.

“I am sad to report that some butterfly gardeners who have purchased plants commercially, with no disclosure that they have been treated, have had their caterpillars die after consuming them. This is unacceptable and we must do better.”

The good news? Many large retailers, now aware of the dangers, have pledged to phase out seedlings and plants containing neonics. Here’s what to know about neonicotinoids and your garden.

What Are Neonicotinoids?

Neonicotinoids (neonics) are a family of synthetic insecticides developed during the mid-1990s. Today, they’re the most widely used class of insecticides in the U.S. and the world. Neonicotinoids are used on agricultural crops, lawns, ornamentals and other home garden plants and some flea and tick pet treatments.

Most likely, you’ll find them in your garden and landscaping because you bought seeds coated with them and seedlings treated with them. They’re also in pest treatments like soil drench, spray and granules.

Some labels disclose their presence, but not all, because it’s not required by law. According to the American Bird Conservancy: “Alarmingly, the concentration of neonics in products sold for residential use on ornamental plants are as much as 30 times what’s allowed in the agricultural sector.”

Why Are Neonicotinoids Problematical?

Neonics are believed to be a leading cause of mass deaths of bees and pollinators, which are vital for plant reproduction. They’re acutely lethal to beneficial insects, but also to birds and, in turn, the whole ecosystem.

“It goes systemic in the plant, meaning it gets into the roots, it gets into the flowers, it gets into the pollen, it gets into the seeds,” says Andrews. “So it affects everything that potentially would come in contact with that plant.”

Pollinators are poisoned not only from the pollen and nectar, but also from the moisture plants release at night, which bees consume. It’s also possible bees die from the honeydew they collect from aphids that feed on plants treated with neonics.

Other detrimental effects of neonics include:

  • Impairing the migratory ability of seed-eating songbirds;
  • Killing earthworms;
  • Creating neurological issues in pollinators that interfere with their foraging and productivity;
  • Affecting the metabolism and chances of survival for future generations of larvae;
  • Reducing queen production in bumblebee colonies;
  • Long-term and widespread contamination of soil and groundwater.

“When neonicotinoids are used as a soil drench around a woody plant, residues can be detected in the soil, tree, or shrub for several years,” says Phillips. “This is bad news for future plantings in the area or for ground-nesting insects, such as solitary bees.

“Also, even after a single application, this insecticide can persist in the soil for months or even years. This long-lasting presence means that even if you apply this chemical a few weeks before bloom, it can still be toxic to pollinators, poisoning the pollen and nectar.”

How To Tell if Seeds and Seedlings Are Treated With Neonicotinoids

There’s no way to tell by sight, so the best way to be sure is to buy from a garden center or retailer that confirms they’re selling uncontaminated plants and seeds.

Also, read the label. Some retailers, like The Home Depot, now require plants treated with neonicotinoids to be labeled as such. If buying plants or seeds from a nursery, look for the USDA Certified Organic label. For treatment products, refer to this list of those containing neonics from the Center for Food Safety.

Sources for Non-Treated Seeds and Seedlings

Local growers can often be good sources for non-treated plants. If you’re having a tough time locating one, larger conservation outlets like National Wildlife Federation, Mt. Cuba Center and Xerces Society can help you find local growers and native plants that will do well in your area.

Garden for Wildlife also sells plants directly, a program Andrews recommends.

“So you can actually get an entire kit of pollinator plants and they know who has grown these plants,” says Andrews.

“Also, the biggest thing is just ask. I work with a lot of independent garden centers that are very, very conscientious about who they buy from. And if they can’t tell you how it was grown, don’t buy it.”