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February 8, 2002

Plants and flowers have spring fever in the middle of winter

WEST LAFAYETTE, Ind. – The sporadic mild winter weather in Indiana has tricked some plants and flowers into thinking it is spring, but a Purdue University expert says most landscape plants and flowers are likely uninjured by the fluctuation of warm and cold temperatures.

Rosie Lerner, Extension home horticulturist, says temperature changes are not unusual in Indiana. Most landscape plants and flowers should be able to endure the fluctuations since severe cold weather has not hit yet.

"The lack of severe weather and extended mild weather we have experienced is certainly out of the ordinary," Lerner says. "Temperature fluctuations, in general, are common but are more often experienced in February."

Warmer temperatures forced perennial bulbs, such as tulips and crocus, out of dormancy much earlier than normal – in some cases as early as November. Even though these plants are making an early arrival, the bulbs should not be heavily damaged in colder weather, Lerner says.

"Cold weather may cause plants to look raggedy and nipped back when they do come up for good," Lerner says. "Foliage that has popped up will be killed back, but the bulbs and roots of other perennials should remain undamaged underground.

"It is possible that spring's display of flowers may be affected, but the plants themselves should be fine. Flowers that did display blooms in the winter could have a reduction in flowering potential this spring. When spring happens, it will be more clear what winter has done."

Even though Indiana has experienced some days of 40 degrees and above, bulbs are planted 4 to 8 inches in the ground and remain cooler than the outside temperature. Bulbs must go through a chilling period of 10 to 13 weeks at 40 degrees or below in order for the flowers to bloom, she says.

Lerner says that trees in their dormant stage are not at risk for damage unless the temperatures get seriously low.

Rain fell over much of Indiana recently, which the state needed due to drier than normal conditions for most of January. Plants and flowers naturally lose moisture through the winter and if it is not replaced, injury is likely, Lerner says.

As most of Indiana experienced rain, the northern part of the state was pounded with icy conditions. Lerner says ice can act as insulation for plants and perennial flowers during the winter months. But heavy icing can damage and break plants and trees.

Lerner says if harsh winter conditions do hit the Hoosier state, there are things that can be done to protect the plants outside your home. If temperatures drop into the single digits, extra mulch can be placed around plants and flowers that have already poked through the ground. Snow also acts as a good insulator, so plants should be left alone if a heavy snowfall hits.

"Most hardy plants have the ability to adjust to moderate temperature fluctuations without much injury," Lerner says. "We just do not know how much winter we still have to get through, and we cannot say what will happen in the weeks to come."

Writer: Jennifer Doup, (765) 494-6682, jdoup@aes.purdue.edu

Source: Rosie Lerner, (765) 494-1311, rosie@purdue.edu

Ag Communications: (765) 494-2722; Beth Forbes, bforbes@aes.purdue.edu; http://www.agriculture.purdue.edu/AgComm/public/agnews/

Related Web sites:
Bulbs Peek Through in Mild Weather
Plant and Pest Diagnostic Laboratory
Snow Is Good News For Gardeners

Purdue News Service: (765) 494-2096; purduenews@purdue.edu


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