Cilantro, Spanish for coriander, is the popular name of the leaves of the coriander plant (coriandrum sativum), an annual herb. The leaves are especially popular in the cuisine of Mexico and Thailand. The whole or ground seeds of the coriander plant are a popular spice called coriander. This plant is grown for its leaves in gardens, as well as in containers.
When a coriander plant is grown for its leaves it is popularly called a cilantro plant. It is soft and hairless, bearing pale pink or white flowers in short flower stalks in the shape of an umbrella. Young cilantro leaves are finely divided, flat and glossy, resembling Italian parsley. When the plant tops out at 24 to 30 inches, it looks spindly and has a few, small secondary leaves. The new, green leaves are used for cooking; the secondary leaves of the mature plant tend to be bitter.
Cilantro does best in full sun and in well-drained soil. It can be planted in the garden as an ornamental, or indoors in a pot in the kitchen where its leaves will be immediately available for use.
Cilantro seeds are sown ½ inch deep after danger of frost has passed. They germinate in seven to 10 days at temperatures of 50 to 85 degrees F.
When the plants are 1 to 2 inches tall they should be thinned from 6 to 8 inches apart. It takes about 45 days from sowing to getting sufficient leaves and thin branches for use in cooking.
When seedlings are about 2 inches tall, the tops of the plants are pinched to encourage lateral branches that produce more leaves. If the tops are not pinched, the plants tend to grow taller and are more spindly with fewer leaves.
Cilantro plants "bolt' easily, meaning that after several days of hot, sunny weather they may jump quickly from the leafing-out stage to producing blossoms and seeds. When a cilantro plant blooms, the cilantro leaves are small, sparse and bitter. The flowers are pinched off and sometimes used as a garnish or added to salads.
The dried seeds, often ground, become the spice known as coriander, which is used in chili, and as an ingredient in curries in Asia.