Wishbone flower, also known as Torenia, is a perennial flowering plant that is typically grown as an annual, although it may overwinter in zones 10 through 11. The plant derives its name from the wishbone-shaped stamen found inside the flower's throat. Wishbone flower is compact, and usually grows no more than 6 to 12 inches in height. The flowers resemble those of snapdragons, and come in white, yellow, pink, purple and blue, depending on the variety. Wishbone flowers are easy to grow and require only minimal care after planting.
Choose a planting location with partial shade and well-drained soil. Sow wishbone flower seeds directly in the garden in late spring, once all danger of frost has passed and the soil has warmed to about 70 degrees F. Scatter the seeds over the planting area, but do not cover them with soil. Germination will occur in two to three weeks and flowers will bloom throughout summer.
Water wishbone flowers regularly to keep the soil consistently moist, but do not allow the soil to become too wet or soggy. Torenia likes moisture; do not allow it to dry out. Water the plant anytime the top inch of soil becomes dry to the touch, usually once per week. Increase watering to twice per week during drought conditions or in very dry climates.
Feed wishbone flower plants with a balanced liquid fertilizer, such as 20-20-20 NPK, or similar, once per month during the spring and summer to encourage prolific blooming. Refer to the manufacturer's instructions for proper dosage and application directions. Apply the first dose two to four weeks after planting and continue with monthly treatments through summer.
Pinch wishbone flower plants back any time the growth begins to look leggy or disorderly. Pinch off excess growth just above a stem node, and new healthy leaves will emerge. A node is an area of the plant's main stem to which a leaf stem is attached. No further pruning of wishbone flower is required.
Check the foliage of wishbone flowers regularly for signs of aphid infestation. Aphids are tiny insects that can destroy a plant if left unchecked. Look for small green, black, gray or brown insects with soft bodies, or a sticky substance on the leaves. Use a water hose with a strong spray to forcibly remove aphids, as necessary.