US farmers have long hoped to extend sugarcane’s growing range northward from the Gulf coast, substantially increasing the land available for sugar and biofuels. Several hybrid canes developed in the 1980s have proved hardy in cooler climes, surviving overwinter as far north as Booneville, Arkansas. But until now, no one had tested whether these ‘miscanes,’ as they are called, actually photosynthesize, and thus continue to grow, when the thermometer dips.