While warm spring weather doesn’t usually bring maple sap harvesting to mind, many people had pancakes and maple syrup on the brain this weekend.

The Minnesota Landscape Arboretum, located in Chanhassen, Minn., hosted its 21st annual Maple Syrup Tours and Sugarbush Pancake Brunch Saturday and Sunday during the height of maple syrup season.

The arboretum, an extension of the University’s Department of Horticultural Science, has more than 1,000 acres of natural land and gardens, including sugar maple trees.

As part of demonstrating the process of making maple syrup, the arboretum taps between 150 and 200 trees each season, said children’s education instructor Kim Kube.

Sandy Tanck, manager of youth, family and teacher education at the arboretum, said the arboretum usually taps during the last two weeks of March and the first week of April, when below-freezing nights and days above 40 degrees Fahrenheit create the correct pressure change in trees for good sap flow.

But with the sudden increase in temperatures, the shortened season is a concern to employees.

Kube said tree bud growth, which is likely to happen earlier this year, signals the end of tapping season, when good sap will no longer flow.

“It started good this year,” she said, “and now we’re a little worried.”

Though the arboretum taps trees mostly for educational purposes rather than for commercial business, Kube said she can still see the difference when she compares past and current production.

The arboretum produced 118 gallons of syrup in 1994, its greatest number, whereas 2005 brought the fewest – just three gallons – because the season was cut short, she said.

If tapping season ends early, it could mean a slight change in programs for those visiting the arboretum.

School groups would get to see a model and learn about Minnesota’s maple syrup history, Kube said, but wouldn’t actually get to see sap flow from a tree on the property.

“There isn’t anything we can do about it,” she said.

Some maple syrup producers in the eastern United States considered tapping in the fall, Kube said, or have even considered starting in January.

Jerry Jacobson, Minnesota Maple Syrup Producers’ Association president, said though Minnesota isn’t a leading maple syrup producer, Minnesota commercial producers and hobbyists are as affected by the weather as larger producers.

He said he personally noticed the shorter season on his farm in the past two years, when production has been down.

In places like Vermont, the United States’ leading maple syrup producer, sap used to run for four or five weeks, but that changed.

“It doesn’t get into those cold nights that you need,” he said. “Everybody’s experiencing it as far as I can tell.”