The fragrant presence of a citronella plant is a familiar sight on many porches and patios during warmer months. This garden addition is sought out for its pleasant, citrus-like aroma, which releases when the leaves are touched. Gardeners often wonder if this tropical plant will survive the winter to reappear next season. Understanding its origin and classification helps determine its long-term viability in temperate climates.
Identifying the Citronella Plant
The term “citronella plant” commonly refers to one of two distinct species, which often leads to confusion. The true source of commercial citronella oil is Citronella Grass (Cymbopogon nardus or C. winterianus), a coarse, clump-forming ornamental grass native to tropical Asia. This plant features long, thin blades and can reach heights of five to six feet.
The plant most frequently sold in garden centers as a “citronella plant” or “mosquito plant” is actually a scented geranium, Pelargonium citrosum. This hybrid is known for its lacy, deeply-lobed foliage and occasional small, lavender-pink flowers. Both plants release a strong, citrusy aroma when their leaves are crushed or brushed.
Hardiness Zones and Perennial Growth
Whether a citronella plant returns annually depends entirely on the winter temperatures of its location. Plant survival is mapped using the U.S. Department of Agriculture (USDA) Hardiness Zone system, which is based on the average annual minimum winter temperature. Both the true Citronella Grass and the scented geranium are tropical perennials.
Citronella Grass (Cymbopogon) is reliably perennial only in the warmest climates, specifically USDA Zones 10 through 12, where temperatures rarely drop below freezing. The Pelargonium citrosum geranium is perennial only in Zones 9 through 11. Neither plant can tolerate freezing temperatures, and even a light frost can be damaging.
Gardeners living in Zones 8 and colder, which includes the vast majority of the continental United States, must treat the plant as an annual. In these regions, the plant will die back completely after the first hard frost and will not regrow the following spring. To enjoy the plant year after year in a cold climate, protective measures must be taken before winter arrives.
Strategies for Overwintering
Gardeners who wish to save their tropical plants from freezing weather can employ several reliable overwintering strategies.
Geranium Overwintering
The simplest approach for the Pelargonium citrosum geranium is to treat it as a houseplant. Before nighttime temperatures consistently dip below 45°F, bring the potted plant indoors and place it near a bright, sunny window. The plant requires at least six hours of direct sunlight daily to thrive indoors. Alternatively, the geranium can be forced into semi-dormancy by reducing water and keeping it in a cool, dark location, such as a garage or basement.
Propagation by Cuttings
A highly effective method for both the geranium and the grass is propagation by cuttings, which allows for smaller, pest-free plants to be kept indoors. Softwood cuttings, three to five inches long, can be taken from the geranium. Remove the lower leaves and root the cuttings in fresh potting soil or water.
Citronella Grass Storage
If overwintering the entire Citronella Grass clump, cut the foliage back to about three inches above the ground. The root ball should then be dug up, divided into smaller sections, and potted. These potted divisions require a cool, bright location indoors for the winter. Water should be provided only when the soil begins to feel dry. Ensure the plant’s survival until it can be safely moved outdoors after the last spring frost, when overnight temperatures remain above 50°F.