Wayne McLaurin could hardly believe it when he saw cranberry plants for sale in the Athens, Ga., chain-store garden center.
A University of Georgia horticulturist and an avid gardener, McLaurin knew better than to buy the plants. But he could see that others were buying them, despite having virtually no chance at all of successfully growing them.
"Cranberries grow in low-pH bogs in cold, Northern climates," he said. "Anybody trying to grow them in Georgia is just headed for disappointment."
Large retail stores offer low-cost plants, McLaurin said. But they may sell plants that, while they may thrive in much of the United States, won't grow well in Georgia.
"People need to look carefully at what they're buying," he said. "The sign may call it a 'hardy' plant, but that's just a word. It means nothing at all if it's not connected to a hardiness zone."
If a plant is advertised as "hardy to Zone 7," it would withstand weather cold enough to survive the winter almost anywhere in Georgia.
As a rule, that means avoiding plants with a tropical origin, McLaurin said.
One such plant is called a "tomato" tree although it isn't actually a true tomato. The plant, Cyphomandra betacea Sendt, is often marketed in Georgia.
"They don't tell you it takes two to three frost-free years to grow it," he said. "It grows well in Brazil. And even if you could coax it to any size in Georgia, the fruit is so seedy you wouldn't want to eat it."
Some tropical plants can be a pleasure in Georgia, but with limits.
"Tropical hibiscus will grow well in Georgia, but they won't normally survive the winters," he said. Many people grow such exotics as banana trees, too, but must either move them inside or take elaborate steps to protect them during the cold months.
In Georgia, the hardiness zones range from 6B in northeast Georgia, with average winter lows from minus 5 to zero degrees, to zone 8B in south Georgia, with winter lows from 15 to 20 degrees.
"But hardiness zones relate only to cold weather," McLaurin said. "The problem is that the most stressful weather we have in Georgia is the heat. Many plants that will breeze through the winter here will wither and die in Georgia summers."
Gardeners trying to grow rhubarb or peonies in south Georgia, for instance, face a real challenge. And while rhododendrons do well in north Georgia, they struggle in south Georgia.
Gardeners should read labels carefully, McLaurin said. Look for other signs that the plant will do well, such as disease resistance.
"On tomato and pepper plants, for instance, look for the VFNT designation," he said. "That means the variety has some resistance to verticillium wilt, fusarium wilt, nematodes and tobacco mosaic virus."
McLaurin also advises buyers to check first with local gardeners to see which plants and varieties have been successful for them.
"Check with county extension agents," he said. "They can recommend good varieties for local planting and point you to experienced local gardeners, too."