What's up with surprising volunteer plants that appear out of nowhere?

Last month I spotted what looked like a weed sprouting in our lawn. I pulled it — and found a peanut shell clinging to the roots.

Odd.

They next day, I found another. Then a few more. Could these possibly be peanut plants? Having lived in Minnesota most of my life, I had never even seen one. Don't peanuts grow in the Deep South and on trees?

I started searching online, and, by goober, peanuts are ground nuts that look just like the plants I kept finding. They're originally from South America and hardy to Zone 5b, which explains why we don't see a lot of them in Zone 4a Twin Cities.

We've had some surprising volunteer plants at our home over the years, including a gorgeous plum-hued heuchera that was planted in the backyard, died, then reappeared in the front yard. But these rogue peanuts are definitely the weirdest and most prolific volunteers we've experienced. I've pulled at least three dozen peanut sprouts, but I'm letting a few grow, just to see what happens.

I'm not the only one finding surprises in my garden.

The University of Minnesota Extension's Ask a Master Gardener program has received an unusually high volume of questions this growing season, said Julie Weisenhorn, Extension educator in horticulture, and about half have come from people seeking to identify a mystery plant.

Hennepin County Master Gardener Steve Miles has several volunteers growing in his own Minneapolis yard.

"A trumpet vine has taken over an entire wall. I never planted trumpet vine. It's tearing into the stucco, but it's pretty," he said. "Creeping bellflower blew in out of nowhere. Last year a mallow came out of nowhere. I let it go. It's a pretty plant."

Many volunteer plants come from airborne seeds, according to Miles. So seeds from a plant that your neighbor is growing can be blown into your yard. Or an animal, such as a squirrel, could carry seeds on its fur and deposit them in an unexpected place.

Other, less pleasant interlopers, like invasive buckthorn, are dropped from the bowels of birds, he said. The seeds in the berries have a laxative effect, and are not digestible.

Weeds and traveling seeds

To inhibit weeds from growing in your lawn, Miles recommends setting your mower head higher, which helps the grass grow thicker, denser roots. Short roots are more susceptible to airborne seeds getting between the blades, he said.

Seeds also can hitch a ride in soil or sod that you purchase, said Weisenhorn. "You expose them by tilling or digging, and some germinate as light hits them."

And they travel in manure that's not composted, she said. "Fresher, newer manure can have seeds that germinate, from something the horse ate."

A compost pile with kitchen waste can produce volunteer plants as the seeds on top break down, she said, resulting in perhaps a cucumber, potato or even an avocado sprouting from a pit. "You could grow anything," Weisenhorn said.

An extended season

"Climate change has radically changed soil temperatures, adding almost a month" to the growing season, said Miles. "You can get three crops of lettuce instead of two."

Because volunteer plants are so commonplace, Minnesota homeowners are advised to be careful what they plant. Some popular landscape plants, such as amur maple and barberry, are on the Minnesota Noxious Weed list because they're heavy seeders and are volunteering in naturalized areas, crowding out other plants, said Weisenhorn.

"If it's on the invasive list, choose a different plant," she said. "Local garden centers can help you select something that has the same fall color" or other attribute that you're seeking.

As for my unexpected peanut crop, the answer can probably be found in my neighbor's yard.

She's a bird lover who puts out whole peanuts in the shell, along with other treats, I discovered. Squirrels also like nuts, and sometimes bury them for a future food source. My neighbor hasn't found any peanut plants in her yard. But we had a resident squirrel hanging out in the attic above our garage late last summer and early fall, before we repaired the opening he had created.