The true citronella plant grows best in U.S. Department of Agriculture hardiness zones 10 through 12. Cymbopogon nardus is a grass native to Southeast Asia from which citronella oil is derived. It prefers to grow in slight shade in a well-draining, loamy soil.
Citronella grass needs around 30 inches of water per year. Daily watering is recommended. If planted in full sun, the leaves may scorch and die.
Citronella has a clumping habit and tends to be propagated through seeds or division. It quickly crowds out other landscape plants with its aggressive growth habit. It grows well in containers but needs dividing every few years.
If grown in rich soil, citronella does not need fertilizer. Use a balanced liquid fertilizer every spring if desired. In colder climates, it is best grown in a container and brought indoors if temperatures fall below freezing.