Fremontodendron is a plant genus in the family Sterculiaceae. Some botanists and growers use its synonym, Fremontia. Its common name is flannel bush, in reference to its hairy texture. Many people get skin irritations by handling or brushing against the plant. The Fremontodendron genus contains only two species, F. californicum and F. mexicanum, but gardeners grow many cultivars of these species.
Typically, the large showy flowers of the Fremontodendron plants bloom from late spring until the middle of autumn. The flowers of the different species and cultivars vary, but generally the flowers are yellow and measure about 2.5 inches (6 cm) across. They are saucer-shaped and five-petaled. The flowers may be rounded at the petal tips or end in long points, depending on the cultivar.
Gardeners who need plants for exceedingly dry climates would do well to investigate the Fremontodendron cultivars. Excessive rainfall or heavy watering usually has adverse affects on the plants and frequently will kill them. The plants often thrive in sandy, dry soil with an occasional watering if it is an unusually dry summer. Generally, growers create a very large bed that is at least 3 feet (1 m) deep in sand.
Generally, flannel bushes thrive when planted against a southern wall where they get warmth from the sun-heated stones. Most gardeners prune off the shoots that have flowered that year to maintain the shrub's shape and size. Gardeners familiar with flannel bushes plant them away from walkways and areas where people might brush against them.
Growers either sow the plant's seed in the spring or root stem cuttings to propagate the plant. Greenwood cuttings usually prefer to root in the early summer. Semi-ripe wood refers to stems that are past the spring growth spurt and have become semi-woody. Growers root these cuttings in late summer to early autumn.
Fremontodendron plants may suffer from root rot. When grown in containers, they might die from stem rot. Sometimes scale insects attack the plants.
There are many cultivars to choose from. Some of the more popular ones are California glory, Ken Taylor, and Pacific sunset. Each of these plants is hardy in climates where the temperatures rarely fall to 20°F (about -7°C). Gardeners generally plant these cultivars because growers bred them to produce masses of the waxy flowers.
Most of the Fremontodendron shrubs grow to heights of 20 feet (about 6 m). Ken Taylor and some other cultivars are spreading shrubs and may reach only 6 feet (2 m) tall, but spread to lengths of about 10 feet (about 3 m). Gardeners should consider these varying growth habits when purchasing the plants for their garden.
When not in bloom, the shrubs are generally nondescript. The leaves are evergreen or semi-evergreen, have five to seven lobes, and are dark green. Typically, they are 2 to 4 inches (about 5 to 10 cm) long and have soft hairs on the underside.