Evergreens? Not so much this year in the Twin Cities

Brown is the new green, judging from the off-color needles on trees and shrubs all around the Twin Cities.

"My yard took a complete beating," said Rick McNabb of Mendota Heights, who lost several large spruce trees, plus a Japanese maple, part of a major landscaping project two years ago. He knew the maple was borderline for Minnesota, but the spruces were supposed to be hardy.

"One is completely dead, and the others are half-brown," he said. "I was pretty upset."

Even some well-established evergreens aren't living up to their name this growing season. Fred Shepherd of St. Louis Park is mourning a mop top conifer planted next to his deck. Usually, it's a "nice, bright Kelly green" that complements the darker foliage of the barberries on either side. But this year, most of the mop top's needles are dry, drab brown.

"I babied it for nine years," he said, watering religiously and adding acidic plant fertilizer. "But I'm pretty sure it's not coming back." At least he's not alone. "Several people on our street lost 20-foot evergreens. They're all brown on one side, green on the other. It's the weirdest thing you've ever seen."

Blame it on this year's wicked winter, which brought "polar vortex" into the lexicon and left a puzzling patchwork of brown and green trees in its wake.

"The winter was very cold and windy and very long," said Mark Stennes, an arborist and plant pathologist in St. Paul. "It was brutal — as bad a winter as I can remember, and I was born in Bemidji."

Bone-chilling temperatures, heavy snowfall and strong winds combined to take a toll on many plants, but evergreens in particular, resulting in a lot of dessication, or "winter burn." Many evergreens were already stressed heading into fall after two hot, dry summers, said Debbie Lonnee, a horticulturist with Bailey Nurseries. "The unfortunate fact is that this 'perfect storm' of conditions did kill some hardy plants."

For weeks, experts have urged patience before pruning, waiting to see if plants with brown areas will fill in with new growth.

"It's been a late, reluctant spring, and heavy pruning too soon can destroy live tissue," said Jeffrey Johnson, woody plant specialist with the Minnesota Landscape Arboretum. "It's still difficult with some shrubs, particularly junipers and arborvitae, to tell what is going to be viable and what isn't going to make it," he said last week.

But now that it's June and we've had a string of warm days, it's more apparent which evergreens survived and which ones didn't. If you have a damaged tree or shrub that is partly green, you can carefully prune away the dieback, although it probably won't be pretty for a long time to come. If there's no life anywhere on the plant — no green, no signs of new growth — "it's toast," said Stennes.

So once you admit defeat and dig up that dead evergreen, what should you do with the void in your landscape? Plant another evergreen, experts suggest. Stennes recommends Norway spruce. "It's a gorgeous tree and can survive [Minnesota winters]," he said.

Lonnee is partial to Black Hills spruce — "one of the best" — if you want a large tree, or Sky High or Medora (both upright junipers) or Techny arborvitae if you want something smaller.

If you like the size, shape and look of the evergreen you had, even if you were disappointed by its performance, try it again, as long as it's hardy for our climate, she said. "You can replace with what you had. This winter was a once-in-two-decades thing."

Planting pointers

But be sure to plant carefully, to give your tree or shrub the best shot at longevity, advised Lewis Gerten, part owner and general manager of greenhouse production for Gertens in Inver Grove Heights. "Planting is key to success with conifers. I have 100 conifers in my yard, and I didn't lose a single one."

Many homes in the Twin Cities have heavy clay soil that's hard for roots to penetrate, Gerten noted. Yet many people, when planting, dig a hole only as big as the pot. "Those roots spiral around," he said.

Instead, dig a cone-shaped hole, very wide at the top, but tapering down to a narrow bottom, for optimal drainage. Without the tapering, "Water will settle at the bottom, and they [evergreens] will get wet feet. Root rot is a problem."

Once the hole is dug, blend the soil with 30 to 40 percent peat moss or potting soil, Gerten said. "All conifers like more acidic soils, and our clay soils are very alkaline and lousy at draining." Peat moss can help with both pH balance and drainage, he added.

And when you invest in a tree or shrub, do some homework before planting. "Read the back of every single label. Don't throw it away," Gerten said.

Keep newly planted evergreens healthy with plenty of water — but not too much — some mulch, and maybe a shot of fertilizer.

And next fall, with another winter approaching, should you wrap your evergreens in burlap to protect them against the elements? Lonnee, for one, doesn't recommend it.

"That negates the whole purpose of an evergreen — winter enjoyment," she said. "In Minnesota, we should not have to do that."

Kim Palmer • 612-673-4784