Marigolds are brightly coloured annuals, which grow to a height of 50cm. There are also some great dwarf varieties, which only grow to around 25cm. The flower colours mainly range from yellows to burnt orange and variations in between.. Marigolds have dark green, lush leaf growth. They flower through spring, summer and into autumn. Marigolds grow best in full sun and fertile, organically rich soil. Heavy soils are acceptable, but they must have reasonable drainage. Marigolds need regular watering to establish well.. Plant in early spring, in warm termperate, temperate and cool temperate area after frosts have finished. Marigolds are used commonly as a bedding plant, in large masses, but they also are a good potted patio plant.