Photo copyright © 2020 Mariposa Native Plants
A medium-sized shrub or small tree, in the Sterculiaceae family, related to the Mallows, the Flannelbush is an evergreen plant found in the chaparral-covered foothills around the Central Valley, and down the Coast Ranges into northern Baja California. It is one of the most spectacular native California plants. It has bright yellow flowers that cover the large shrub in early spring. It grows very quickly, and it can grow as fast as four feet per year when its growing conditions are optimal.
F.californicum early in spring, Bootjack area of Mariposa County. Photo copyright © 2020 Mariposa Native Plants.
F.californicum is found in the interior hills and mountains that surround the Central Valley of California from Redding, through the Bay Area, and along the coast down into Baja California. It is also found in the foothills of the Sierra Nevada, east of the Central Valley, from Redding down to Bakersfield. Its habitat runs from sea level to 10,000 ft. (3000m). Sun: full sun. Temperature: cold tolerant to 15°F (-10°C). Soil: sandy, even gravelly and rocky soils. Soil acidity: pH from 6 to 8.
Fairly easy to care for once established. The Flannelbush is sensitive to pruning; minimize any trimming of the plant and avoid any cutting on the larger branches of the shrub. Moreover, this plant does not tolerate summer water, once it has been established. The best time to plant Flannelbush from the container is in the fall, just before winter rains arrive. It's also feasible to plant F.californicum from from the nursery container in the spring for Mariposa and surrounding counties. A specimen that is planted early in the year from a 1-gallon container should be given supplemental water (1 gallon, 4 liters) every week for the first summer. Double this amount for a Flannelbush coming out of a #2 container and do it proportionately for a #3 or a #5 container. After the first winter rains, do not water the plant. Avoid supplemental water once the plant has been established (in the second year). Since it grows quickly and--having been through one wet season-- requires no supplemental water, the site for setting down a Flannelbush should be carefully chosen.
Foothills (to 2500 feet), lower mountains (2500-3500 feet), and sunny spots in the middle mountains (3500-6000 feet).
Close-up image of F.californicum blossoms in spring, Sierra foothills. Photo copyright © 2020 Mariposa Native Plants.
Well, in our experience the Flannelbush is deer resistant. However, in their book Trees and Shrubs of California, J.D. Stuart and J.O. Sawyer note that "Deer find its foliage very palatable". It would be prudent to plant Flannelbushes from the container into the ground with a gopher screen and a deer screen.
Very few pest problems with this plant.
Generally speaking, Flannelbush seeds need to be treated with fire and smoke in order to break their dormancy. To do this, the collected seeds are placed on a bed of soil in a fire-proof pot, covered with pine needles, oak chips, or scraps of paper, and a match is lit to the kindling. This little campfire is then stifled a bit with a metal or flame-proof lid so that the result is a low-grade, very smoky fire. The seeds in the pot can be then set out into the wet fall/winter weather for germination. It turns out that some germination is possible, but a bit rare, perhaps 10% but not much more, without any fire and smoke treatment. The plant does not submit readily to stem propagation, and, again, this shrub does not appreciate pruning.
Native Americans used strips of the bark for cordage and fashioned the split branches into storage containers.
The largest specimen of F.californicum grows in North Fork, Madera County, California. It is 26 feet tall and the trunk is 13 inches in diameter.
#1 container, about 1 gallon; deep #1 container, #2 container, about 2 gallons; and #3 (3 gallon) container.