In Jack's Zone 8 garden, palm grass bursts into a fountain of showy flower spikes by mid-August. In warmer zones blooming begins in June.
Palm grass is an evergreen tropical looking grass with wide, accordian pleated leaves that are 1-3 ft (0.3-0.9 m) long and 2-5 in (5-15.24 cm) wide that resemble the foliage of young palms. In frost free climates a clump of palm grass can get 8-10 ft (2.4-3 m) tall; in temperate zones, it can grow 3-5 ft (0.9-1.5 m) tall in a single season. The inflorescence is a greenish cylindrical spike that stands above the leaves on a slender, arching stalk that reaches several feet above the foliage. 'Rubra' has purplish midribs. Cultivars with striped leaves are available.
Palm grass is native to India. It has become a troublesome weed throughout much of the tropical and subtropical Pacific region.
Culture Light: Full sun to partial shade. Moisture: Palm grass prefers moist soils and can be planted at the edge of lakes and ponds where it will thrive (if not actually take over). Amazingly, palm grass is also happy growing in dry shade and established plants are relatively drought tolerant. Hardiness: USDA Zones 8 - 11. This is a tropical grass that suffers when temperatures fall below about 40ºF (4.4ºC), and dies to the ground when it freezes. If the roots don't freeze, though, it usually comes back in spring. Palm grass is evergreen in zones 10 and 11, and a recurring perennial in zones 8B and 9. Propagation: Propagate palm grass by division and by seed. It will self-seed in warm climates but seedlings are shallow rooted and easy to eliminate.
Even when not in bloom, a clump of palm grass adds a tropical touch as demonstrated by this specimen at the Atlanta Botanical Garden.
Palm grass has a coarse texture that may not be easy to fit into some garden designs. It is best grown as a specimen for the tropical look provided by its wide, palmlike leaves. Palm grass is a good choice for tub and container culture and stored indoors for the winter. Some gardeners in cooler zones grow palm grass in the ground in summer, then dig it up and bring indoors in winter. In frost-free climates palm grass is grown in the partial shade of palm trees, in the woodland garden, and along walkways (see Warning).
The genus Setaria (usually called bristle grasses) includes about a hundred species, many of which are pernicious weeds in agricultural fields. The ornamental bristle grasses are grown for their showy foxtail-like flowering spikes that make memorable impressions when backlit. The attractive, rich green foliage makes a beautiful background for flowering plants and imparts and exotic tropical ambiance. Some gardeners even remove the flowering spikes because they detract from the foliage (which also eliminates the need to remove seedlings from the bed the following spring).
This plant is NOT recommended for Zones 9 and 10. Although it is not yet listed as an invasive species by the Florida Exotic Pest Plant Council it has become a notorious pan-tropical weed that's disrupting habitats from Africa to Asia. Caution is also recommended in Zone 8 - especially in moist or wet soils.