Tropaeolum majus, or Nasturtium, is a fast growing climbing annual native to the Andes Mountains in South America. The bright green leaves are peltate and from 2-7 inches (5-17.5 cm) across. The plants climb by using coiling petioles. All plant parts contain mustard oil and flowers, and young fruits are used as seasoning and pickling. Leaves and flowers are used in salads and have a peppery flavor. They are of very easy culture and are great as hanging basket plants, providing winter color in the cool greenhouse.
Blooming: In the greenhouse, the plants bloom all winter through late spring. The 2.5 inch (6.5 cm) wide flowers come in shades of yellow, orange and red. They have a long spur and are mildly fragrant and very showy.
Culture: Tropaeolum majus need full sun with a well-drained soil and cool temperatures. In the greenhouse, we use a soil mix consisting of 1 part peat moss to 1 part loam to 2 parts sand. The plants are well watered and allowed to dry slightly before watering again. They do not need fertilizing during the growing season. We grow these during the winter months in the greenhouse. The minimum low temperature runs around 48°F (9°C) with the daytime temperatures running around 65°F (17°C). As temperatures rise in late spring, the plants are allowed to set seed. Seed is then collected for the next winter's plants. Here in Oklahoma, these plants can be grown outside in mild winters. If frost damages the plants, you just plant more seeds.
Propagation: Tropaeolum majus is propagated from seed. Seeds germinate in 14-21 days.
Tropaeolum majus was featured as Plant of the Week March 24-30, 2006.
Guide to Past Plants-of-the-Week:
Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically the late Cal Lemke, who used to be OU's botany greenhouse grower and an avid gardener at home as well. If the above links don't work, then try the overview site. You may also like to look at the thumbnail index. ©1998-2012 All rights reserved.