Flowers, trees face downside to this week's warmup

Though a week of springlike temperatures in the middle of February is sure to make people feel good, there's really not much upside for vegetation as long as the possibility of cold weather remains, according to an expert at Morton Arboretum in Lisle.

The potential for trouble differs greatly for trees, shrubs and flowers, and even among species within those categories, said Sharon Yiesla, the arboretum's plant knowledge specialist.

While the warm weather encourages leaves and flowers to begin their spring cycles, it's their ability to bounce back from a subsequent freeze that varies, she said.

“If the flowers get hit by cold, they're gone,” Yiesla said. “Trees and shrubs will get more leaves.”

A rise and fall of temperatures stresses all plants, and even trees and shrubs will need to put in more effort to produce more leaves this year after losing their first ones.

But gardeners shouldn't panic. Instead, they can take advantage of this rare opportunity for a midwinter assessment of their plants and soil cover, Yiesla said.

One thing that can be done for any new growth is to cover emerging bulbs with a layer of old leaves, she said.

The longer and more intense the current heat wave, the harder its impact on this year's flowers and trees would be. That's why Yiesla is encouraged by the forecasts that winter will return to normal as soon as this Saturday.

“I'm personally glad we're getting back to seasonal temperatures,” she said.