THUNBERGIA alata (black-eyed susan) is the only species of this genus grown as a house plant. It is a fast-growing twining plant with at­tractive flowers. Although actually a perennial, it is usually treated as a temporary house plant, to be enjoyed during the flowering^ period—which normally lasts from late spring to late fall—and then discarded. Its leaves are tooth-edged, triangular to arrow-shaped, up to 3 inches long and wide, borne on slender stalks along the twin­ing stems. Two-inch-wide flowers, which are produced on short stalks from the leaf axils, consist of an inch-long tube flaring out into five petallike lobes. Petal-lobe color varies, but in all forms there is a central deep chocolate brown "eye" (the entry point to the tube for insects); the tube itself is dark purple, and each flower is backed with a pair of |-inch-long, pale green bracts. In the most common form of T. alata, T.a. 'Aurantiaca,' the lobes are orange-yellow; in T.a. 'Alba,' white; in T.a. 'Lutea,' bright yellow.

Buy young thunbergia plants only a few weeks old in the spring. They usually twine around three or four thin sticks pushed into the edge of the pot but they will also climb up a string fixed to the side of a window. In either case, they should be cut down and discarded when flowering stops.


Light Thunbergias must have bright light with two to three hours a day of direct sunlight to flower properly.

Temperature These thunbergias will do well in any normal room tempera­ture during their stay in the home. Nevertheless, they can tolerate much cooler conditions—down to 50°F.

Watering Water young plants mod­erately, enough to make the potting mixture moist at each watering, but

allowing the top half-inch of the mix­ture to dry out before watering again. As these swift-growing plants get big­ger and begin to flower, they need more water. Throughout the flower­ing period water them plentifully, as often as necessary to keep the mixture thoroughly moist.

Feeding Give standard liquid ferti­lizer to flowering plants every two weeks throughout the year.

Potting and repotting Use a soil-based potting mixture. Young thunbergias should be moved on when they grow too big for their original pots. As soon as a number of roots begin to appear through the drainage hole in the bottom of a pot, move the plant into a pot two sizes larger. Probable maximum pot size needed: 6 inches.

Propagation Seed can be grown indoors without much difficulty if sown in early spring. Three seeds should be planted in a single 3-inch pot containing a moistened soil-based potting mixture. They will usually germinate in three to five weeks if kept in a warm room in a position where they get bright filtered light, and are watered enough to make the mixture moist, but with the top half-inch of the mixture allowed to dry out between waterings. The new plants will grow quickly and may be trans­ferred to individual 3-inch pots and treated as mature thunbergias when they are 6 inches high.

Special points Be sure to remove faded flowers by nipping them out with the fingertips, if this is not done regularly, the flowering season will be needlessly brief.

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