Torenia (torenia fournieri) is also called wishbone flower or bluewings. Its flowers bloom throughout late summer and early fall, and come in various shades of blue, rose, yellow, pink, purple or white, depending on your chosen variety. Most variety have purplish blue flowers with a yellow throat. True to its name, Torenia displays two short wishbone-shaped curved stamens.
Torenia is a summer annual that belongs to snapdragon family. It is native to Africa and Asia but with proper care, Torenia can be easily cultivated in any temperate areas. It loves hot and humid weather, and grows well in semi-shaded location. Torenia plants stand 8-12 inches high and bush out 6 inches wide. Torenias make good companion plants for impatiens and ferns. In clusters of three or more, they look beautifully when grown in woodland bowers, rock gardens, borders, pots, and along paths or walkways.
Torenia is propagated from seed. It requires rich, well-drained soil and a warm climate. Since the seeds are slow-growing and quite small, it is best to start them indoors 10-12 weeks before the last frost date in your area. Cover the seeds lightly with compost-enrich soil and water well. Avoid dislodging the seeds when watering. Germination takes about 10-15 days at 70 degrees Fahrenheit. Outdoor planting can be made when the seedlings are large enough to handle and if all the danger of frost has passed. Transplant them at 6-8 inch spacing in between. Again, water well to collapse any air pockets and to let the moist soil touch the roots.
How to Grow Torenia:
The outdoor spot for transplanting must have rich, well-drained and moist soil. Increase drainage by spreading a half inch of clean sand over your planting area. Make sure that the plants will receive sunlight each day. Although Torenias thrive during summer in semi-shaded location, they need high humidity and will not tolerate being dry. Water them regularly, especially in hot weather, but do not overdo it. Make sure not to leave your Torenias standing in wet soil or the roots will rot.
Add 1-inch layer of mulch around the plants. Begin by mulching 4 inches away from the stems to allocate room for growth. Refurbish the mulch as often as necessary to continually maintain 1-inch layer.
Once your Torenia plants reached about 8 cm high, pinch back the growing tip of the stem to encourage branching. This extra care will give you bushy, compact and healthy-looking plants. Removing spent bloom heads or “deadheading” is not really necessary to improve the appearance of your Torenia plants. In fact the seedheads are quite pleasing to the sight. In some cases though, plants may self-seed so watch for tiny seedlings in the spring.
Using a balance 10-10-10 NPK fertilizer, fertilize Torenia plants once every month. Make sure to follow the directions and dosage properly. Prevent root burn by watering the plants before and after applying the fertilizer.
Torenias are usually disease- and pest-resistant. However, in rare cases, they may encounter fungi diseases such as powdery mildew and Botrytis. Such problems result to yellow and gnarled leaves. Insect pests such as whitefly and aphids that suck nutrients from the plant may also leave behind curled/gnarled leaves.