GARDENING:
Is pruning necessary to keep rangoon creeper blooming?
Q: My rangoon creeper and russelia are blooming beautifully. Do I need to prune either in order for them to continue blooming? Dave Sherron, Houston
A: Rangoon creeper, Quisqualis indica, is a sun-loving vigorous vine with long, tubular blooms that flare at the ends and age from whitish-pink to red for a great summer display. Fragrance is most intense at night.
This aggressive perennial, which spends warm/hot months growing and blooming, needs substantial support. Prune after the last freeze in early spring, if needed or desired. You can trim spent blooms, which can encourage more growth and eventually more flowers.
Horticulturist and former Mercer Botanic Gardens director Linda Gay offers these interesting tips on training and pruning the vine:
“I have found if rangoon creeper can be spiraled around a post and not allowed to grow and float freely in the air, it will flower more. The pressure on the stems, at the bends in the spiral, throws clusters of flowers. Most vines, if grown around a post and trained in a corkscrew fashion, will produce more flowers than their wild and free cousins. Rangoon creeper is a monster vine and needs a huge space to run crazy or a post to wrap and compress.
“I had 8-foot posts in the vine garden to grow display plants at Mercer. As I trained the vines, I wrapped them around the post starting low and keeping the runners close to each other, compressing the plant in a small area for display. This spiraling/ corkscrewing/training allowed me to manipulate the plant growth, and the end result was I was forcing the plant to bloom, and the bloom cluster occurred at the bend on the vine. It was a cool discovery.
“As far as trimming, yes, trim back and train regrowth on something to create the pressure on the stems, an obelisk or an arbor or even a post.”
Remove the spent flowers on your russelia or fountain plant to encourage more blooms. Trim the growing ends to shape the plant. Remove any dying or dead canes.
Fountain plant, Russelia equisetiformis, is a low-care, reseeding perennial with arching, slender, rushlike branches and an abundance of orange-red tubular flowers spring to frost. It blooms best in full sun but tolerates part shade.
This plant tolerates most any well-draining soil. It is droughttolerant once established. It works well in a large container, too. It may freeze back but is usually root-hardy.
Q: My Louisiana Irises are not liking the direct sunlight and heat. They had looked so lovely along the side of our driveway. As these irises dwindle in the heat, I was wondering if you would advise that I pull them, store them in the refrigerator and replant in fall in another location that doesn’t receive as much sunlight? Any suggestion as a replacement? John Paine, Houston
A: These water-loving native American irises bloom best with sun, especially months of winter sun. Some do like a bit of protection from summer afternoon sun.
Handsome sword-shaped Louisiana foliage, which begins to grow in fall, is at its best winter and spring. But much of the foliage typically yellows and plants enter dormancy as rays and heat intensify this time of year.
Remove dead foliage as it appears for a tidier look. Mulch to slow soil-moisture loss as well as weed growth. Spread pine needles or leafmold to prevent rhizome sunburn.
If there’s space in the flower bed, add hot-weather bloomers such as purslane to shift the focus from any tired iris foliage. New iris growth will emerge in early fall.
If you decide to move your irises, choose a bed with at least a half day of direct sun. Divide and transplant mid-August into October. Cut the foliage back, leaving about an 8-inch fan of the swordlike leaves. Dig and divide the horizontal thickened roots (rhizomes) you wish to move. There’s no need to refrigerate. Plant the rhizomes just beneath the surface of a fertile soil. Do not expose rhizomes to the sun as they might burn. Water and mulch. Keep the rhizomes moist.
Drift roses, ornamental grasses or rosemary might be replacement options for your sunny, driveway bed.
Louisiana irises vary from 2 to about 6 feet tall among the species. The spring blooms come in many colors and are most striking in the landscape. Remove spent flowers, so the plant will spend all its energy on stronger foliage rather than developing seed pods. The seed don’t come true to the mother plant.
The iris rhizomes will spread and naturalize in the garden with moist, compost-enriched soil.
Water year-round, and flood the irises twice in January when they’re growing and preparing their spring blooms.
Apply an 8-8-8 fertilizer when it’s cool in November and in January. Fertilize less vigorous plants again after spring blooms.