i think that if you see "eyes" you should go ahead and plant. then again, i may be thinking of the wrong plant!

from http://www.webindia123.com/garden/flowers/blheart.htm :
"Dig up in early spring but be sure to handle the roots very carefully because they are extremely brittle. Each piece of root division should have an eye or bud however, the root need not be more than 3 feet long. New planting locations should be well marked and cleaned removing dormant stems remaining if any."