Hibiscus moscheutos 'Old Yella', also known as Fleming's Hardy Hibiscus, is a perennial herbaceous shrub native to swampy areas from Massachusetts to Florida to Alabama. 'Old Yella' is of hybrid origins. In my quest for a yellow hardy hibiscus that would live outside in zone 7, I came up with this beauty. Plants will reach 4-6 feet (1.2-2 m) tall with an equal spread. Leaves are lanceolate to broadly ovate, unlobed to shallowly 3-5 lobed, green above and white pubescent below and will reach up to 8 inches (20 cm) long. The plants have a long blooming season here in zone 7. Plants are hardy in the landscape in USDA zones 4-9.
Blooming: Plants will start blooming in June and will continue until fall. I was quite surprised when the pale creamy yellow flower buds opened into a creamy white flower with a dark red center. The flowers, like most hibiscus, last only one day, but there is a profusion of flowers. Each individual bloom will measure up to 10-12 inches (25-30.5 cm) across. Very showy!
Culture: Hibiscus moscheutos 'Old Yella' needs full sun to partial shade with a moist soil. I don't grow these in the greenhouse, but I have grown them for years in my yard. The area where they are planted was amended with peat and compost worked in to 12 inches (30 cm) deep. Since the plants are native to swampy areas, here in Oklahoma they need to be watered deeply at least once a week. We fertilize our plants every 6-8 weeks with a balanced fertilizer. As plants start to grow in the spring we stake each individual stem, as the flowers tend to bend the stems from their weight. During the flowering season, we keep the plants deadheaded to promote more blooms. In late August, we let the blooms stay on the plants so we can collect the seed. As winter approaches, we collect the seeds and wait until the plants have died back before we cut the stems back to the ground and mulch them well to help them overwinter.
Propagation: Hibiscus moscheutos 'Old Yella' are best propagated from seed, but large clumps can be divided. Seed will germinate in 14-21 days at 68-70°F (19-21°C).
Hibiscus moscheutos 'Old Yella' was featured as Plant of the Week June 24-July 8, 2011.
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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.