Marigolds are one of the most popular annuals grown in North America. Their sunny yellow, orange and red flowers give the garden a cheerful look from spring to fall. In warmer climates marigolds are grown year round. They thrive in ordinary soil and are prized for their profuse blooming habits. Many gardeners grow marigolds for their medicinal value and as an insect repellent.
Marigolds are of the plant genus Tagetes, one of 51 annual and perennial plants in the daisy family. The various types of marigold have green pinnate leaves and white, golden, orange or red flower petals in a ray or disc floret shape. Many species of marigolds have a distinctive musky, pungent scent. The scented oils that the flower exudes repel harmful insects. For this reason marigold is used as a companion plant in vegetable gardens.
Marigolds are known to have been used in the Aztec culture of Central America. The National Garden Bureau found the first written account of marigold use in a 1552 manuscript about herbs. It was noted that marigolds could be used for physical and psychological problems. The Aztec word for marigold is cempoalxochitl. Seeds from these marigolds were taken by sixteenth century Spanish explorers to Spain and European cultivation began.
In early Latin American culture marigolds were an important part of religious ceremonies. Garlands of marigolds are still used to decorate altars for All Saints Day. When family gravestones are strewn with marigolds it offers them protection from negative influences. Hindu ceremonies also make extensive use of marigolds in garlands to honor gods and goddesses.
The National Institutes of Health report a study that suggests the marigold species Calendula has an antimicrobial effect. Native medicine systems use it for healing liver, stomach and intestinal problems. Calendula flowers are also used as a wash for conjunctivitis and thrush, and other skin irritations. Traditional Chinese Medicine uses marigold to dissipate heat, expel colds and break up phlegm.
Marigolds are used to repel harmful insect pests on vegetables such as squash, tomatoes, eggplant, potatoes and beans. Marigolds release thiopene, which is a chemical repellent for nematodes. Marigolds repel aphids and the whiteflies around tomatoes. It also kills bindweed, one of the most common weed problems in vegetable gardens.