With these temperature swings, only strong flowers survive

If you feel stressed going straight from cranking up the heat to turning on the air-conditioning, imagine how all those Mother's Day gift plants feel. Pity the poor petunias, impatiens and begonias.

“All those hanging baskets people get for Mother's Day, if they were under an eave, they are probably OK. But if they got frosted, you're going to see it,” says Kris Bachtell, vice president of collections and facilities at the Morton Arboretum in Lisle, where temperatures dropped to 30 degrees early Monday. “If you already planted your pepper or tomato plants, you might not like it.”

The Aurora Municipal Airport in Sugar Grove reported 29 degrees. Temperatures dipped to 33 in Barrington, 32 in Elgin and West Chicago, and 30 in Mundelein, McHenry, Waukegan and Lisle, as pockets of the suburbs suffered frost.

“Everybody knows I know plants, so I was making home visitations like a doctor would,” Bachtell says of the Naperville neighborhood where he lives. “My oregano, my geraniums, I brought those in.”

He advised neighbors to cover their pepper and tomato plants with tents made of bed sheets to trap the warmth of the ground and keep frost off the plants. Of course, Bachtell's plant prescription for today, when temperatures are expected to rocket into the mid- to upper 80s, is the direct opposite.

“You've got to take those structures off so the plants don't get too hot,” he says. “These are stressfully odd times. Plants have to be extra hearty here.”

Not all of the thousands of plants at Goebbert's Farm & Garden Center in South Barrington are equipped to handle the extremes.

“The night before, we lost a couple of pepper plants that were left out, “ says Goebbert's manager Sue Murdock, who had staff members bring plants inside or cover them at night with burlap bags until Monday's warm-up. Mother's Day is the traditional start of planting season, but Murdock says customers were told to hold off until this week.

“Now, I'm getting itchy. I haven't planted anything yet,” says regular customer Doreen Kwasek of South Barrington, who put off buying a cartload of hydrangeas until Monday.

“I waited because I knew it was going to frost,” says shopper Paula Ichert of Hoffman Estates, who started planting Monday morning and came back that afternoon to buy more plants.

While this area has seen freezing temperatures as late as May 25, and Bachtell remembers a hard frost at the arboretum as late as May 28, the National Weather Service says now we should be done with that frost nonsense until fall.

But that doesn't help suburban gardeners who got nailed overnight Sunday into Monday.

“Those violets don't look too healthy,” National Weather Service meteorologist Richard Castro says of a frosty photograph submitted by Wauconda gardener Judy Lee Webb and immediately posted on the weather service's Facebook page.

The arboretum doesn't plant vulnerable species until Memorial Day, and, after a quick survey Monday, Bachtell says he thinks the cold weather didn't kill any plants on the grounds.

However, homeowners who were impatient to get their impatiens planted before Mother's Day might have to buy new ones.

Cold can break down the cell walls in the plants, making them turn mushy and black, Bachtell says.

Some species, such as pansies and snapdragons, generally are strong enough to withstand a mild frost, he says.

But a late May freeze can kill much sturdier plants, even trees, Bachtell says, explaining how the arboretum lost some trees from China one year while native species, such as the bur oak, survived.

“They've seen this before,” Bachtell says of the bur oaks. “It might have been 2,000 years ago, but it's in their DNA.”

Today's expected temperature swing of more than 50 degrees might challenge the all-time daily shift of 58 degrees set on Feb. 13-14, 1887, when temperatures went from zero to 58 degrees, and on March 11-12, 1972, when a 15-degree day was followed by a 73-degree high.

We probably will set a record for the greatest May one-day warm-up, eclipsing the 50-degree upturn from 38 degrees on the last day of April to 88 degrees on May 1, 1992.

The wacky temperatures are paying dividends this spring for flowering trees and bushes, however. Temperatures were just high enough to coax out blooms, and then the cool temperatures served almost like a refrigerator to preserve the red, pink, purple, yellow and white blossoms.

“Wednesday will be stunning,” Bachtell predicts, noting temperatures will be in the mid- to upper 80s and then drop off at night and later in the week. “You'll open everything up and then it will cool down.”

Murdock says Goebbert's staff members look forward to opening greenhouse windows.

“It will be nice to turn the heat off,” Murdock says, offering a shrug and a smile. “We're set up for this. It's like this every spring. This is Chicago.”