Hothouse flowers these aren't. More like cool houseplants that flower.

Cyclamen, Christmas cactus, poinsettia, kalanchoe.

"The idea of specialized plants for the cold-weather holidays … all started when growers wanted to supply plants for decorating for the holidays," said Guy Metzler, Penn State Cooperative Extension educator for commercial horticulture who serves 21 counties in Western Pennsylvania including Butler.

"When fuel prices were low, when coal prices were low, we weren't concerned with paying for heat so much.

"As fuel prices rose, growers started to look for plants that would bloom under cooler temperatures, plants like cyclamen and primula and cineria. They won't grow outside in the winter, but these are actually very tough plants. Homeowners shouldn't be afraid to grow them inside."

Another flowering holiday crop is the Christmas cactus, which can bloom as early as Thanksgiving, Metzler noted.

To get the plants to flower in time for the holidays, growers control how much light the plants get.

"All these bloom on short day responses. Growers schedule them so they'll bloom from Thanksgiving through the Christmas holidays," he said.

A different species of cactus, known as an Easter cactus, is grown to bloom for the spring holidays.

"One plant American growers started growing and then Canada kind of took them over is kalanchoe," Metzler said. "They require warm temperatures to start but can finish at relatively cool temperatures. These are from a group called post-harvest, the same group as poinsettia. They will bloom a long time, make a really nice houseplant."Jeff Berta, production manager at Slippery Rock Greenhouse, will ship about 600 cyclamen plants this holiday season. He only sells wholesale to places like grocery stores and nurseries. He does other business in herbs, perennials and exotic annuals.Inside his cool and slightly humid greenhouse, cyclamen are blooming in shades of pink, peach, red and white. "Flares" are the ones edged in a contrasting color."They have one flower per stalk and there's usually about five stalks," Berta said.In the best plants, flower buds can be seen down in the middle of the plant, he said, sometimes 30 to 40 below the surface. The leaves usually always look the same, a nicely patterned dark green. Some are a little more silvery, he noted."Out of all the plants, they probably have about the longest post-harvest flowering period," Berta said.

"The thing with them is not to water them too much. You want to wait until they're almost wilting to water them."Ever-popular poinsettias predominate at Tom McMeekin's Quality Gardens in Valencia.About 10,000 poinsettias have been grown for sale and for fund-raising events for area groups such as Holy Sepulcher Roman Catholic Church.On display are 27 varieties this year, including:Jingle Bell - red bracts that look like white paint was dropped on themPink Shimmer - like Jingle Bell variety only in pinkFreedom Fireworks - only on market a couple years, it's solid red with leaves that are more long and pointedMars - red of course, and short and stocky, good for a table centerpiece, McMeekin said."A generation ago, poinsettias grew really tall, so they would fold them over and wrap them back up again. It got really messy," McMeekin said.

He also named amaryllis and ivy topiaries as popular holiday plants."Amaryllis have to come from the southern hemisphere now, like from Africa, if they're going to bloom before Christmas," McMeekin noted.Another popular Christmas flower is the quick-blooming paper-whites, he said. "If you get them now, you want to see them still in the dirt, not even buds."Still, flowering plants grown in Pennsylvania are best suited to the climate here."We really like people to think about flowering plants because that's our identity here," Metzler said. "They are living things and treat them accordingly."Brenkle's Farms and Greenhouses and Zang's Greenhouse, both in Butler, also grow this kind of specialty crop, according to Metzler, who has worked with them.So if your poinsettia ever caught a draft and dropped all its leaves, don't be afraid to try again. They grow hardier all the time.