Mimosa rupertiana, also named Sensitive Briar and Eastern sensitive plant, is a fun plant to grow. The Sensitive Plant folds up its leaves when touched or exposed to a flame or heat. Native to Brazil, it grows to a height of 50 cm with a spread of 30 cm. Mimosa rupertiana is common in rather moist waste ground, in lawns and in open plantations. This ornamental plant can also be grown indoors in pots or outdoors as an annual in the cooler zones.
The flowers are pink pompoms with yellow tips from which develop long seed pods. The flowers are appearing in Summer and has numerous filaments. The stem is erect, slender, red-brown and branching. Bristles on seed pod cling to fur and clothing.
The leaves are fern like and pale green with opposite bipinnate leaflets. When this plant is touched, the leaves fold and the stems droop. Recovery is prompt, and the action can be repeated endlessly without harm to the plant. These movements are called seismonastic movements, reaction to physical shock. At night, the leaves will also fold and bend in movements known as nyctonastic movements, reaction to absence of light.
Hardiness zones 9 -11, (-5°C/25°F,4°C/40°F) in Winter. This plant requires a medium light exposure, an evenly moist soil, and temperatures between 60-85°F. The plant dislikes root disturbance. Mimosa is sensitive to over watering. Winter temperatures should not fall below 60°F; if they do get chilled, then the plant suffers with yellowing of leaves and stems.
Due to its ability to fix nitrogen from the air it does well on poor soils. Use a soil mix consisting of 2 parts peat moss to 2 parts sand and one part perlite. The soil should be kept evenly moist but not saturated. During the growing season, the plant are fertilized on a weekly basis with a balanced fertilizer diluted to 1/2 the strength recommended on the label. During the Winter months, fertilize on a monthly basis and water sparingly.