Choose companion plants that tolerate the sunny, dry conditions often found along fences. Purple fountain grass (Pennisetum setaceum) is hardy in zones 9 and 10. This 4-foot-tall grass grows in clumps of arching foliage and produces pink-purple flower spikes from midsummer through late fall. Century plants (Agava americana), also hardy in zones 9 and 10, grow to 6 feet tall. These drought- and salt-tolerant shrubs have long, gray-green, succulent fronds edged with spines. They bloom with yellow-green flowers and create a striking accent under tall palms.
If your palms line a walkway, choose low-growing species to balance the tall palms. Purple Heart (Setcreasea pallida “Purple Heart”) is hardy in USDA zones 9 through 10 and forms a mat of bright-purple foliage. This groundcover grows well in sun and well-drained soil and requires regular irrigation. The dwarf jasmine (Jasminum parkeri) grows to 1 foot tall but spreads to 30 inches wide. This deciduous shrub, hardy in zones 9 through 10, blooms with fragrant yellow flowers in summer and prefers full sun and well-drained soil.
With a grouping of queen palms, choose flowering plants to form a lush, tropical effect. The pigeon berry (Duranta erecta) has lustrous, dark foliage and blooms with spikes of blue-white flowers. This 6-foot, evergreen shrub is hardy in zones 9 and 10 and grows best in sunny, well-drained sites. Purple Fountain salvia (Salvia x “Purple Fountain”) grows to 2 feet tall and has glossy, dark foliage. It blooms from spring through fall with bright-red flowers and grows well in full sun. This perennial is hardy in zones 7 through 11 and looks best when planted in groups.
When selecting companion plants for a single queen palm, choose species with varying heights to create interest around the tree’s base. The cape leadwort or plumbago (Plumbago auriculata) grows as a rounded shrub to 10 feet tall. It blooms through the summer with white and blue flowers and has pale-green foliage. It tolerates drought and heat and prefers sunny sites in zones 9 through 11. The climbing snapdragon vine (Asarina antirrhinifolia) grows quickly to 8 feet long. It is hardy in zones 8 through 10, grows best in full sun and blooms with red, purple, white or pink flowers, depending on cultivar. For low color, plant four o’clocks (Mirabilis jalapa). These 3-foot-tall perennials bloom in spring with red, yellow, white, pink and multicolored flowers. They thrive in sunny, well-drained sites in zones 9 and 10 and require regular irrigation.