Temperatures in the Philly region may not visit freezing again until the end of next week, with a run of 70-degree days possible in the interim. And after some substantial winter napping, the region’s plant life is going to notice.
Horticulturalists offered a variety of perspectives on what effects the surprisingly enduring snow and ice snow cover and Arctic freezes have had on the regional flora and what may be ahead.
They allow that while it wasn’t exactly a vacation, spending five weeks and change under a glacier and snowpacks hasn’t been all bad for the plant life.
But as the great thaw accelerates, they have cautionary words for home gardeners: Watch your step.
And meteorologists warn that if you expect the thaw to be linear, you clearly have wandered into the wrong part of the country. Winter and spring are still in a nasty turf war that can turn ugly in March in the Northeast.
Five weeks under the covers had benefits for Philly’s plant life
Officially, Philadelphia has logged 36 days of snow cover of at least one inch, including 23 consecutive days after the Jan. 25 snow-and-ice fest. The timing of that snowpack was fortuitous in that it “insulated the ground, protecting perennials, grasses, and marginally hardy bulbs” from the Arctic freezes that followed, said Lisa Roper, horticulturalist at Chanticleer Garden in Wayne.
Said Sky Deswert, garden educator with the Norris Square Neighborhood Project in Philly, “Without the snow, there is a greater risk that dormant plants and roots will suffer from the cold.”
The snow was beneficial “to things like blue hydrangeas, insulating the stems from the cold,” said Bill Cullina, executive director of the University of Pennsylvania’s Morris Arboretum & Gardens in Chestnut Hill.
Overall, said Roger Davis, a landscape manager at Longwood Gardens in Chester County, “Snow cover does not typically cause any problems for most plants in our home gardens.”
Unfortunately, it also typically doesn’t cause problems for voles, those plant-nibbling so-called field mice that evidently had a field day.
But the winter also offered significant challenges
“Voles have been active underground, eating roots and even the crowns of grasses and perennials,” said Cullina. Snow has given voles ideal cover from an impressive lists of predators, including owls, foxes, raccoons, and cats.
They can kill shrubs and small trees by chewing at ground level, said Chanticleer’s Roper.
Deer also have been nuisances. “Heavy snow cover makes it difficult for deer to find food,” she said. “The deer will start to eat plants they typically leave alone.”
At Morris Arboretum, Cullina said, “They have been browsing needled evergreens that they normally ignore.”
He added that frost-heaving, in which soil expands and contracts with fluctuating temperatures, is back after taking off much of this century. “This can force recently planted perennials and even shrubs as well as bulbs out of the ground.”
Said Roper, “Keep your eye out for plants pushed out of the ground; you can stick them back in if you see them.”
Some of the broad-leaved evergreens, such as rhododendron and hollies, may have suffered from “the combined effects of sun reflecting off the snow and frozen ground that prevents water uptake,” said Cullina. That can lead to leaf burn and defoliation.
“Not much you can do at this point except wait until the plants leaf out …and then prune off any dead branches,” he said.
Shrubs planted near the eaves of houses may have suffered from another hazard — rooftop snow, said Theresa Smith, senior vice president of NaturLawn, a national lawn service company with several outlets in the region. “When you have snow falling off in heavy pieces, it’s definitely going to damage some of those softer plants.”
And beware of salt damage on lawns, particularly near well-salted roads and driveways, said Smith. Salt can dehydrate vegetation. She also warned that prolonged snow cover can yield bumper crops of “snow mold,” a fungus that thrives in cold, moist conditions.
If you see those unsightly straw-colored mold patches, rake them out and put down grass seed on the bare spots, Roper said.
‘Mud season’ has arrived in Philly. Watch where you step.
The ground has assumed a certain spongelike quality now that most of the snow is melted, and it’s going to take some time to wring out the sponge.
Cullina said that reminiscent of his native Maine, it “feels like Philly is getting a little taste of mud season this year.”
Smith strongly advises gardeners to keep off the mud as much as possible. “You don’t want to add to the compaction that’s already there,” she said.
The tighter the soil gets, said Longwood’s Davis, the more it reduces the air spaces. “Foot traffic has more effect on wet soil than you might think.”
And beware the moods of March
Smith cautions against yielding to an agricultural spring fever, despite the promising temperature forecast for the next several days. Starting Sunday, the high temperatures could reach 70 degrees on four or five days, said Bob Larsen, a senior meteorologist with AccuWeather Inc.
Smith votes for harnessing planting ambitions during March, a notorious transitional month when the aggressive warm air masses clash with the retreating winter.
Her birthday is in March, and she recalls receiving snow as a not necessarily welcome birthday present more than once.
Philadelphia’s last verified blizzard occurred in March, in 1993; in 1958 over 50 inches of snow fell upon Morgantown, Chester County, during the so-called equinox storm, and 20 inches fell in Philly on April 1, 1915.
“Home gardeners just need to relax a little bit,” she said, “and wait for the weather patterns to become more consistent.”
