If you've found a market for switchgrass and decided to start growing it, Michael Casler suggests you ask a few detailed questions before buying.

“My colleagues and I have done a number of trials to try to define where varieties are best adapted. One mechanism for increasing productivity is making sure you have very good, adapted materials,” says the U.S. Dairy Forage Research Center geneticist from Madison, WI.

“We learned that most varieties can be moved one hardiness zone north or south of where they came from. If you're in hardiness zone 5, you may be able to choose a variety that originally comes from hardiness zone 4 or hardiness zone 6. But don't go beyond that,” he warns.

At this point, most regions of the U.S. have a couple of switchgrass varieties that adapt well to them, Casler adds. “There are a couple of good choices here in the Midwest and the North. Then you go South and you have to change to a different variety, and into the Deep South you have to switch to a completely different set of varieties.”

Just a handful of companies are marketing switchgrass seed, which has increased in price as the supply has tightened.

“I tell people to be very, very careful. They need to ask detailed questions.” Those include:

• Where did the germplasm to develop this variety come from?
• Where was the breeding done?
• What's the expected adaptation region?

If those three questions don't match up, they need to be very wary,” says Casler. “For example, if someone says the material came from Georgia and it was bred there but that the variety should be adapted all the way up into Wisconsin, I wouldn't believe that.

“We would never recommend more than a one hardiness zone change unless it's been extensively tested and there is documented proof that that variety will survive two or three hardiness zones north or south of where it came from.”

He also suggests that growers talk with extension personnel who have a good idea of what the best adapted varieties are for their regions.

Also, switchgrass seed can have a lot of dormancy in it, allowing weeds to germinate before the crop can, Casler says. “If I were buying it I probably wouldn't like to have any dormant seed. Or a very, very tiny amount.”