Has spring arrived early on the Great Plains?
During this unusually warm March, the cranes and the geese are well along their northward journey. The bees are buzzing and the forsythia, magnolias and daffodils are blooming. Some emerging dandelions have even been spotted on the University of Nebraska-Lincoln campus.
With spring on nearly everyone's minds, some of UNL’s climate and horticulture experts offered some thoughts about the recent warm(er) weather.
Has spring truly arrived early on the Great Plains?
While another cold snap can’t be ruled out, Mother Nature is clearly ahead of schedule.
State Climatologist Martha Shulski says average temperatures appear to be 10 degrees warmer than normal – in the 48-degree range, compared to the typical 38-degree range.
“Cross your fingers, but with warm night temperatures, warm day temperatures and increasing day lengths, we are ahead of schedule.”
Climatology professor Ken Dewey said he agrees.
“My photo archives of the past 20 years shows some vegetation, forsythia, magnolia, etc., are as much as three weeks ahead of schedule,” he said. Dewey’s data shows that the period from Feb. 1 through March 13 was the fifth-warmest on record in Lincoln.
Data from the High Plains Climate Center showed that soil temperatures in Lincoln ranged from 45 to 51 degrees on March 6, about 6 to 9 degrees higher than normal, said Sarah Browning, an extension educator with UNL in Lancaster County.
Why is this happening?
It’s a mixture of climate change and recent weather events, Shulski said. Late winter and early spring temperatures have been marching upward for decades, she said.
An El Niño climate cycle is affecting weather patterns worldwide, increasing the chances of a warmer-than-normal late winter and spring in North America. And the lack of snow cover this year in the western High Plains has accelerated the impact of warm sunny days.
Dewey said El Niño and global warming are heightening the natural up-and-down climate variability on the plains.
“Overall, our winters have had a warming trend for several decades,” he said. “Nebraska has three or four weeks less snow cover now, compared to the 1980s.”
How does this affect lawn care and gardening this spring?
Gardeners and landscape managers already are running out of time for some early spring chores. Soil temperatures have already reached the point where pre-emergent herbicide should be applied as soon as possible to the lawn, Browning said.
“We’re right in the window to put pre-emergents down, though it’s much earlier than normal,” she said.
With many trees and shrubs already breaking dormancy, landscape managers should take care with the pruning shears, Todd said.
“The pruning window is slamming shut for anything that’s beginning to break its buds to bloom this year,” she said, adding that it’s probably too late to apply dormant oil spray to fruit trees.
Perennial plants and ornamental grasses should be cut back and heavy mulches lifted so that new growth doesn’t blanch under heavy cover, she said.
Gardeners itching to get outside can go ahead and plant pansies. Todd said she thinks they could also plant spinach and lettuce, but Browning says she thinks the frost risk still is too great for tender lettuce. Browning said the soil is warm enough for onions.
Gardeners should remember, however, that the last frost of the season usually occurs in the last half of April. Todd said not to prune rose bushes in mid-March, because a cold snap would damage the stems below the cuts. She also said to be prepared to lightly cover perennials if frost threatens.
At this point, there is not much gardeners can do to protect their greening shrubs and turf in case of a late snow or cold, Browning said. However, it appears many early-season bloomers, such as magnolia and forsythia, will be done blooming before another cold spell appears in the forecast.
Is this the new normal?
It’s too soon to say definitively, the experts said. While average temperatures in March have been consistently warming since the 1960s, the trend for April is far less pronounced, Shulski said. This past winter was about 5 degrees warmer than usual, making it one of the 10 warmest winters on record in Nebraska. February was about 8 degrees warmer than normal, but it was not a record.
“It remains to be seen if this will be the warmest March on record,” she said.
Browning noted that March was colder than normal in both 2014 and 2015.
“This March is warmer than normal, but I wouldn’t say it’s a trend necessarily.”
Dewey, however, said he’s already seen changes in regional gardening practices as a result of changing climate.
“Pests are no longer dying off in the winter. Wine vineyards are flourishing in Nebraska because our winters are milder. Garden centers now offer guarantees on less hardy plant varieties that are surviving only because the winters are trending to warmer,” he said. “In a warming climate superimposed over the ups and downs, these types of winters will become more common."