Next threat of hard freeze not expected until Tuesday
But this winter and spring has been anything but normal.
Normally, the National Weather Service in Sullivan starts issuing frost advisories in May, when gardeners get a little scared spring blooms might be harmed.
But with the warm weather giving the growing season a few weeks head start, forecasters have started issuing notices in April, meteorologist Mark Gehring said.
He doubted Thursday night’s light frost—temps dipped to between 30 and 32 around Janesville—caused any damage to plants.
Temps will rise today through the weekend, and the next threat of a hard freeze will come Tuesday night, he said. A hard freeze that can hurt plants requires temps in the upper 20s or lower for several hours, he said.
Gardeners should use lightweight fabric to cover anything that’s flowering for the hard freeze, said Jeff Bailey, greenhouse manager at Nature’s Touch in Janesville.
“If those freeze, the blooms will fall off,” he said.
Anything still in the process of leafing out—shrubs, perennials and trees—should be fine, he said.
Warmth from a house can protect nearby plants, but plants in the open should be covered, he said.
Sheets should cover foliage but don’t need to be tucked under and pinned down, he said. Avoid plastic for covering because condensation can freeze on it, he said.
Water sprinklers can be used to protect larger areas, although Bailey admitted that could get costly.
Even if it freezes hard, most plants will bounce back.
“Basically, anything that gets singed on the edge of the leaves, they’ll recover from that,” he said.
Rob Ten Eyck, owner of the Ten Eyck Orchard in Brodhead, didn’t find any damage to his crop from Thursday night’s low temps.
“Even open blossoms won’t be killed at 32. It has to get down probably under 28,” he said.
“If it doesn’t get any colder than (Thursday) night next week, I think we’ll still be all right,” he said.
Most of his trees are on hills where the temperature can be 8 degrees higher than at the orchard’s buildings 60 to 70 feet below.
If some apple blossoms are damaged, it might not affect the harvest because only about 10 percent of blossoms are needed to make a good crop, he said.
In a normal year, he uses chemicals to limit the number of apples allowed to develop. Otherwise, he said, the trees would produce masses of golf-ball sized fruit.
The weather has resulted in a “real drawn-out bloom this year,” he said. The early heat brought trees quickly to the “pink” stage—the stage when blossoms are swollen but not open. “Pink” came four to five weeks early, but recent cooling has slowed things, he said.
Overall, he estimates his orchard is two to three weeks earlier than normal.
The average April snowfall in Madison is 2.6 inches, Gehring said, so flurries or minor accumulations are still possible.
“Given how mild the winter/spring has been, I doubt that’s going to happen,” he said, “but I can’t guarantee it.”