See more of the story

Corn growers — or anyone with a connection to the U.S. corn belt — knows the saying: Knee-high by the Fourth of July.

This sing-song expression for judging a crop's success is at least a century-and-a-half old. Over time, it has grown less accurate a measure with the advancement in seed genetics and a changing climate.

But the spring's soggy start may make the phrase relevant again this season.

"This year is the first year I can ever remember we won't have corn knee-high by the Fourth," said farmer Shayne Isane of rural Badger, Minn., just a few miles south of the Canadian border. "It's an old adage — as a lot of times we'll be waist-high or shoulder-high."

Much of Minnesota endured a dreary, wet and cold spring, keeping farmers to nervously pace living rooms, waiting for a chance to plant seeds.

According to data from the U.S. Department of Agriculture, 98% of the state's crop was finally in the ground by June 6 — about 20 days behind 2021. Such delayed plantings means the old-fashioned phrase will correctly match corn's height in some parts of the state.

Over 400 miles south of Isane's Badger farm, Faribault County grower Gary Prescher said the state's far southern belt that hugs Iowa was largely spared the extreme moisture and cold, meaning corn may hit the "elephant's eye" measure — popularized by Rodgers and Hammerstein's "Oklahoma!" musical — this July.

"The early-planted corn is approaching chest high," said Prescher, who's been farming since the 1970s.

For many longtime farmers like Prescher, the old expression still invokes memories of their youth, the days of mechanical weeding and waiting for warmer soil temperatures.

The first reference to the phrase first appeared in archives of the Minneapolis Tribune, a Star Tribune predecessor, in 1867 — the paper's first year — when an Indiana correspondent commented on "knee-high" wheat evoking "the appearance of a green ocean."

Thirteen years later, in June of 1880, a Wadena County observer noted the corn "looks well" and would undoubtedly hit that "knee high" height by the nation's July birthday.

And not all corn is the same.

"If you're driving around the country, not all corn is commercial feed corn," Prescher said. Some — such as edible sweet corn and organic corn crops — may need to raise their chins to hit that knee-high height.

University of Minnesota corn agronomist Jeff Coulter says modern-day hybrids — which he said have more "vigor" than seeds of yesteryear — and changing weather patterns have made the old adage less relevant.

"They planted later in those days," said Coulter. "We've gotten more warm weather it seems like than in the past."

On Wednesday, Coulter — in a bucket hat and backpack — tallied height of corn in a notepad at the U's agriculture campus.

"This is probably the more common size," said Coulter, pointing to a plot of May-planted corn that was at or below the thigh. A patch of corn planted in April was much taller.

Coulter points out that the mid-June heatwave bodes well for the corn crop — which, he said, will probably end up becoming a "good year" by autumn when combine tractors take to the fields.

New developments in corn hybrids could see so-called "short stature corn" soon reaching the state, making the old phrase relevant again.

"We're about as far north as you can go," Isane said. "We like to joke ours is always short-statured."

Oliver Kelley Farm, an educational farm near Elk River run by the Minnesota Historical Society, uses agricultural practices of the 1860s, when many pioneers first tilled land only recently held by the state's Indigenous populations.

This spring, staff planted nearly an acre of corn at the farm along the Mississippi River. It was an "exceptionally rare" heirloom variety called "improved King Philip" that originated in New England, said Mary Challman, program supervisor at the Oliver Kelley Farm.

"We know that this was a specific variety that Oliver Kelley mentioned being grown by the mid-19th century," Challman said.

Agriculture today is, of course, a big business. But the industry's heart runs on folk wisdom passed down from grandmothers to grandsons, from uncles to nephews.

Challman said there are other crops that enjoy whimsical rules-of-thumb: Plant potatoes by Mother's Day. Early fall if spiders make their webs thicker. Some gardeners only plant on a waxing moon.

"The thing that is so cool about agriculture is even with the industrialization and mechanization, it still represents a very deep interaction with the land," said Challman, and that means wisdom is also passed on.

That's how a 19th century phrase that should've gone extinct has remained.

Modern farmers are still at the mental gristmill, coming up with new rhymes.

"Maybe," Prescher said, "good rain makes good grain?"