To celebrate its 60th anniversary last spring, the Minnesota Landscape Arboretum planned a spectacular display of 38,000 tulips. Deer that live in the area responded with a special event of their own: a big tulip feast.
Before the flowers had even broken through the soil, deer ate the bulbs. When remaining bulbs began to sprout, deer ate the plants. By the time they were done, the hoofed gluttons had scarfed down 10,000 tulips.
So gardeners are hard at work this week to prevent a repeat of that ruminant banquet. They’re installing about three-quarters of a mile of fencing to close a gap in the more than 2 miles of fencing that already rings the arboretum’s 1,200 acres.
“This year we’re not messing around,” said Erin Buchholz, the arboretum’s pest management specialist.
It’s an ongoing challenge keeping hungry critters away from the vast array of flowers, plants, shrubs and trees — the largest and most varied garden in the state. Sealing all the openings is next to impossible; for instance, many deer enter via the paved visitors’ entrance, trotting past the gates without bothering to pay admission.
Arboretum staffers deploy a range of nontoxic deterrents, from stinky substances to plastic coyotes to scary sounds. “Pesticides are a last resort,” Buchholz said.
One repellent made of rotten eggs is as unappetizing to deer, rabbits and squirrels as it would be to humans. Another made of pig blood terrifies animals, its smell suggesting that something was slaughtered nearby and they could be next.
Yet another spray uses cayenne pepper that gets incorporated into plants, giving the vegetation a three-alarm spiciness that animals don’t like — unless they’re extremely hungry. If a long winter like last season’s keeps deer from reaching other food, they may be famished enough to take what they can get.
“If I was starving I’d eat a jalapeño salad — I think we all would,” said Erik Lemke, a landscape gardener at the arboretum.
Spiciness doesn’t bother geese, which don’t devour the gardens but can be messy and potentially hazardous around small children, Buchholz said. Geese are repulsed by a spray whose active ingredient is also used as grape flavoring.
“Don’t ever try feeding a bird grape Kool-Aid,” Buchholz said.
At the nearby Horticultural Research Center, a nonpublic part of the arboretum (both are arms of the University of Minnesota’s Department of Horticultural Science), staffers protect cultivated grapes and apples with netting, fake hawks and speakers blasting bird distress calls — the avian version of the “Neee! Neee! Neee!” in Alfred Hitchcock’s “Psycho.”
“It’s kind of like animal horror music,” said Jim Luby, a U horticulture professor and director of research at the arboretum. “When another robin hears that call, it gives them the signal that one of my specie’s compatriots is in danger, so I’d better get out of here as well.”
Deer have become a much greater problem in recent years as surrounding Carver County becomes more suburbanized, said Alan Branhagen, the arboretum’s director of operations. Subdivisions have replaced open fields, squeezing deer into tighter quarters and chasing off potential predators.
And humans, from the deer’s perspective, have been outright hospitable, setting out gardens like deer snacks. Tulip bulbs are the truffles of the deer menu, a special delicacy, Branhagen said. And deer were left especially hungry this year as last winter’s snow season stretched into April.
“They get used to people, and that’s when the trouble starts,” Branhagen said. “It’s really impacting a lot of the flora out this way.”