A quick plunge into the low 30s — even lower by some accounts — is a reminder that spring in Southern Oregon doesn't necessarily mean warm and sunny.
The National Weather Service Tuesday afternoon issued frost and freeze warnings, predicting temperatures last night would drop as low as 27 degrees in parts of Jackson and Josephine counties.
The Weather Service warned that unprotected plants could be damaged or killed.
Spring freezes can be a challenge for professionals and home gardeners alike, although nursery operators are more adept at handling the vagaries of spring weather.
"It's shipping season, as well, when we're getting a lot of new plants in," said Eric Hagerman, a horticulturist at Shooting Star Nursery outside Central Point. "Many of them come from the Willamette Valley, where it isn't as cold, and even occasionally from California, and those plants are definitely not as acclimated to a cold snap like this."
Shooting Star has an unheated greenhouse on its 5 acres, where it winters more delicate plants.
"There are hardy plants that are perfectly fine if they are in the ground but would be damaged if they were in a pot," Hagerman said. "This is all within our normal experiences."
Over at Cascade Nursery on Table Rock Road, Allen Payne relies on frost cloth to protect plants.
"Anything like rhododendrons that have bloomed out, when it freezes it could make the flowers look poorly, but it won't hurt the plant," said Payne, who has been raising and selling plants for 32 years.
He said new growth on hydrangeas, nandinas and grapes will handle most of the cold's bite without long-term damage.
"We cover things up with frost cloth and hope for the best," Payne said.
Frost blankets — lightweight spun fabric — add two or three degrees of protection, Hagerman said. It might not seem like a lot, but it serves the purpose. In general, he said, 32 degrees — when water freezes — is a pretty good standard, but "in some cases" damage can begin at 35 degrees.
"We might see some of the new growth stunted or flowers lost, but generally speaking, we buy things that are hardy enough to withstand this setback," Hagerman said.
Freezing temperatures send shivers down the spines of those responsible for the well-being of plants at the South Medford Grange Co-op.
"We check the temperature every day as it progresses, and if it hits 40 degrees, we take action," said Lynn Baker. "We don't want to lose a lot of merchandise."
Annuals such as geraniums, fuchsias and impatiens are all carefully protected, as are sensitive summer vegetables.
"If the tomatoes and peppers are on carts and mobile, we roll them inside," Baker said.
Even so, she said, sometimes cold mornings take a toll.
"It happened last year, right about now," Baker said. "The wind-chill factor adds some variables we have to deal with."
The lesson for backyard gardeners is patience; April showers can be accompanied by hail — and worse.
Summer vegetables, such as peppers, squash, cucumbers, tomatoes and green beans — along with annual flowers — are the most susceptible to frost.
"They are the kinds of things that only grow in summer," Baker said. "It's still too early to plant vegetables and most annuals. Those who already did are the people who should worry. They should know better than to plant before the middle of May."