In our zone 7, it will not survive the winter outside. And, during the summer it likes a little afternoon shade.
Each fall, I cut off the fronds and trim them to the circumference of a small peach. After a few weeks in water, they sprout shoots and roots and are ready to plant.
And, yes, this plant is called Cyperis alternifolius and Cyperus involucratus due to a professional disagreement among botanists, according to one author.
|Propagate umbrella palm (Cyperus alternifolius).|
According to Dr. T. Ombrello - UCC Biology Department Umbrella sedge is native to Madagascar, Mauritius, and Reunion Island but has naturalized in South America and the West Indies.
"Besides propagation by seed, the Umbrella plant has an unusual means of vegetative reproduction. The plant’s stems are relatively weak and tend to crimp and bend over when subjected to even the slightest pressure. This results in the stem apex and leaves being submerged in water, or at least contacting the moist marsh soil. Soon after, the bent stem sends out roots and shoots from beneath its leaves, establishing a new plant. This can be easily duplicated at home by cutting a whole stem from the plant, removing the leaf tips and lower stem to make it more manageable, and placing what remains upside down in a glass of water."
The original frond does not look good but notice the new shoot on the left and the root on the right.
At John & Jacq's Garden, they have photos of rooting the fronds in moist soil. Here's that link.