Valerianella locusta is a tender salad green that grows best in cool weather. Mâche is an annual plant that grows wild in many areas. One of the common names, "corn salad," derives from its tendency to grow wild in corn fields. There are also several mâche varieties with larger leaves and sweeter flavors that have been bred for backyard gardening.Mâche grows in low rosettes of elongated, dark green leaves up to 4 inches long. Although technically hardy in zone 5 to 8, where it will over-winter, this short-lived plant is typically grown as an annual in all zones.There are two types of mâche from which to choose: large-seeded and small-seeded. The small-seeded varieties only grow well only in cool weather, while the larger-seeded varieties can withstand the initial heat of summer and may resist bolting well into June.Mâche is usually sown by seed in late fall or early spring. In warmer climates, it may serve as a winter crop. Leaves can be harvested at any time, but the plant will fully mature and will complete its life cycle in just 40 to 70 days.