Despite their common names, both French (Tagetes patula) and African (Tagetes erecta) marigolds belong to the same genus, Tagetes, within the Asteraceae family. The "African" marigold is a misnomer, as all Tagetes species are native to the Americas, specifically regions from the southwestern United States down through Mexico and into South America. The names "French" and "African" were likely assigned by European traders who sourced the plants from different locations. Tagetes erecta, the African type, tends to be larger and was perhaps first introduced from Africa, while the smaller, more compact Tagetes patula was associated with French breeding programs.
The most striking difference between these two types lies in their physical structure. African marigolds (Tagetes erecta) are robust, tall-growing plants. They typically reach heights of 1 to 3 feet (30 to 90 cm) and have a strong, upright, and sometimes woody central stem. Their leaves are large, pinnate, and deeply divided, with lance-shaped leaflets that are a smooth, blue-green color and emit a potent, pungent aroma when crushed.
In contrast, French marigolds (Tagetes patula) are notably smaller and more compact, usually growing between 6 to 18 inches (15 to 45 cm) tall. They exhibit a bushy, spreading growth habit with multiple branching stems. Their foliage is finer and more delicate, with dark green, lance-shaped leaflets that are serrated along the edges. The scent of their foliage is equally distinct but is often described as more sharp and spicy compared to the African variety.
The floral displays offer another clear point of differentiation. African marigolds produce massive, fully double, pom-pom-like flower heads. These blooms can be enormous, reaching up to 5 inches (12 cm) in diameter. They sit prominently on thick, sturdy stems above the foliage, making them excellent as cut flowers. The flower heads are primarily composed of dense, overlapping ray florets, with the disc florets often hidden from view.
French marigolds, on the other hand, bear smaller, prolific flowers that rarely exceed 2 inches (5 cm) across. While they can be double, they are more commonly semi-double or even single. A key identifier for many French marigold cultivars is the presence of a distinct central disc of raised, button-like florets surrounded by a single or double row of flat ray florets. They bloom profusely, creating a solid carpet of color, and their flowers often exhibit striking bicolor patterns of red, mahogany, orange, and yellow.
From a horticultural perspective, each type has adapted to slightly different conditions. African marigolds thrive in full sun with well-draining soil and are more heat-tolerant. However, their large, heavy flower heads can be susceptible to damage from heavy rain and strong winds. They are often used as background plants in borders or for dramatic seasonal color.
French marigolds are renowned for their resilience and adaptability. They tolerate a wider range of soil conditions and are more resistant to damp weather. A significant trait of French marigolds, particularly heirloom varieties, is their production of root exudates containing thiophenes. These compounds are known to have nematocidal properties, making them popular companion plants in vegetable gardens to help suppress root-knot nematodes in the soil.
