(Coriandrum sativum) Cilantro is an herb that does double duty in the garden! The pungently flavorful leaves, called cilantro, offer complex flavor to a number of dishes, while the seeds, known as coriander, are used as a spice. The plants prefer cool weather and will bolt in the heat of summer. However, you can succession sow as a way to keep cilantro on the table longer. Direct sow seeds ¼ to ½ inch deep, four to six inches apart, starting three to four weeks before the last frost. Plant seeds in successions every 2-4 weeks throughout the season for a steady supply of this distinct and useful herb.