Many gardeners are drawn to “citronella plants” for their aromatic foliage and perceived ability to deter insects. The question of their perennial status frequently arises. Understanding “citronella” involves distinguishing between different plant types and their varying responses to different climates.
Understanding Citronella Plants
The common term “citronella plant” often causes confusion because it refers to two distinct botanical species. The true citronella plant is Citronella Grass (Cymbopogon nardus or Cymbopogon winterianus), a coarse, clump-forming ornamental grass. The other plant often called ‘citronella’ is the ‘Citronella Geranium’ (Pelargonium citrosum), a scented geranium. While both emit a lemony fragrance, their growth habits and hardiness differ significantly.
Citronella Grass Perennial Status
Citronella Grass is a true perennial in tropical and subtropical regions, thriving outdoors year-round in USDA Hardiness Zones 9 to 12. In these climates, the grass can grow quite large, reaching heights of 5 to 8 feet and widths of 3 to 5 feet. However, in cooler climates with freezing temperatures, Citronella Grass typically behaves as an annual. It will die back with the first frost and will not regrow from its roots in the spring without protection.
“Citronella Geranium” Perennial Status
The ‘Citronella Geranium’ is considered a tender perennial. It can survive year-round in frost-free climates, generally USDA Hardiness Zones 9 to 11. In these warm zones, it can develop a woody base and grow up to 2 feet tall. For gardeners in temperate regions with cold winters, the ‘Citronella Geranium’ is typically grown as an annual and will not survive outdoors through a cold winter.
Extending Plant Life
Gardeners in colder climates can extend the life of both Citronella Grass and ‘Citronella Geranium’ by bringing them indoors before frost. For ‘Citronella Geraniums,’ this involves moving potted plants inside when nighttime temperatures consistently drop to 45°F. Plants can be trimmed back by about one-third and placed in a bright, sunny window, or under a grow light.
Similarly, Citronella Grass grown in containers can be brought indoors for winter. Both plants require reduced watering during their indoor period, allowing the soil to dry slightly between waterings. Taking cuttings from either plant in late summer or early fall is another effective method to ensure new plants for the following season.