French marigolds, also known as dwarf marigolds, are herbaceous, annual flowering plants in the Asteraceae (Aster) family. Common relatives include zinnias, dahlias, cosmos and calendula. Smaller than their cousins, African marigolds, the French variety have a mounded, compact growth habit that many gardeners enjoy. Although less popular than other types, French marigolds produce flowers from spring until fall and are widely available in garden centers and nurseries across the country.
Despite their name, French marigolds are not native to France. They grow natively in Mexico and areas of Central America. The plants adapt well to poor soil, heat and drought, but cannot tolerate cold temperatures or wet soils. The plants die back after a few freezes and grow as annuals across the United States. Gardeners typically plant French marigolds in dry, sunny places where they thrive with proper care and the plants are often found growing wild in dry areas of their native habitat.
French marigolds reach up to 12 inches in height with a spread of up to 18 inches by the end of the growing season. The plants produce abundant single or double flowers that reach up to 2 inches across and appear in shades of yellow, orange, red, maroon or bi-color. The plant's simple, dark-green leaves exude a pungent fragrance when bruised and grow along grooved, hollow stems with multiple branches. Stems grow upright initially, but become mounded and bushy as the plants spread throughout the season.
Common in annual flower gardens, French marigolds typically find homes in edgings, beds, containers, mass plantings and cut flower gardens. Frequently used as companion plants to other flowers or vegetables, French marigolds repel many different types of pests. The flowers also contrast well against dark green foliage plants and gardeners often use them for ornamental purposes. When cut, the colorful blossoms are used in floral arrangements and displays. The plant's leaves are considered edible and the blooms are sometimes fed to chickens to improve the color of their eggs' yolks.
The most obvious benefit of growing French marigolds is the profuse, vividly colored blooms that appear in the summer months. Numerous cultivars are available, all with their own colors and growing habits. Other benefits include the plant's tolerance to extreme heat and drought and the ability to deter pests from the garden. The scent of the foliage repels insects and the roots expel a chemical that repels nematodes in the soil.
French marigolds grow best in full sun, although they tolerate partial sun in very warm climates. Moist, well-drained soil is best for the plants, but they can handle dry conditions for extended periods without serious damage. They will not thrive in full shade or in wet, soggy soils. French marigolds require 6 to 9 inches of space between themselves and other plantings. Weekly watering is beneficial unless natural rainfall exceeds 1 inch. Deadheading helps extend the blooming period.