Cilantro looks like flat leaf Italian parsley, but the leaves are thinner. It grows in a rosette of stemmy leaves that are ready to harvest shortly after planting. Young leaves have the best flavor, so be sure to harvest often. It is a fast-growing annual except in milder climates where it will overwinter. Cilantro grows tall and blooms at the end of its life, usually after the weather gets hot. After it blooms, harvest the seeds - they are what you buy in spice jars as coriander, another common ingredient in Asian cooking. You can grind the seeds or use them whole. Some gardeners also let the seeds drop to make new plants.