The citronella plant is widely recognized for its strong, fresh, lemon-like scent. This popular name often causes confusion because it refers to two distinct types of plants: the true Citronella Grass (Cymbopogon nardus or Cymbopogon winterianus) and the scented geranium often marketed as the “Mosquito Plant” (Pelargonium citrosum). True citronella originates in tropical regions of Asia, while the scented geranium is a hybrid. While both plants share the characteristic citrus fragrance, their chemical composition and effectiveness differ significantly. This fragrant herb is valued for its scent and its traditional use in managing insects.
Primary Function as a Natural Pest Deterrent
The most common reason people seek out the citronella plant is its reputation as a natural insect deterrent, especially against mosquitoes. The leaves contain volatile compounds, including citronellal, citronellol, and geraniol, which contribute to the strong scent. This aroma is pleasant to humans but works to confuse or mask the chemical cues that pests use to locate a host.
The living plant only releases a noticeable amount of scent when its foliage is physically disturbed, such as by crushing or brushing against the leaves. Therefore, a potted plant sitting passively on a patio offers minimal protection. For the plant to be an effective deterrent, the oil-containing cells must be broken to release the volatile compounds. Scientific studies show that the concentrated oil can disrupt mosquitoes’ ability to find a host.
The effectiveness of the living plant is limited because the concentration of repellent oils released is low compared to commercial products. While the live plant may deter some pests in a localized area, it is less potent than highly concentrated essential oil formulations. The plant’s primary role is to provide a reservoir of aromatic compounds that can be manually activated or harvested.
Clarifying the Plant vs. the Essential Oil
A significant distinction exists between the living plant purchased at a garden center and the potent commercial essential oil. The highly effective oil used in sprays, candles, and lotions is derived primarily from the tropical species of Citronella Grass (Cymbopogon). This oil is extracted through steam distillation, where steam is passed through the harvested leaves and stems, pulling out the concentrated aromatic compounds.
Commercial citronella oil is a complex mixture, often containing high percentages of citronellal and geraniol, which are the main insect-repelling components. This highly concentrated extract is significantly more potent than the oil naturally released by the scented geranium (Pelargonium citrosum). The geranium sold as a “citronella plant” is primarily an ornamental novelty with limited repellent power unless the leaves are actively crushed and rubbed onto the skin. Consumers should be aware that the plant they buy is rarely the source of the commercial oil used in branded repellent products.
Other Applications in Home and Health
Beyond deterring pests, citronella oil has a long history of use in wellness and household applications. In traditional systems like Ayurveda and Traditional Chinese Medicine, the oil was used to address issues such as digestive complaints and joint pain. Modern aromatherapy utilizes the oil’s bright, citrus-like scent to create a sense of relaxation and uplift mood. Diffusing the oil helps alleviate feelings of anxiety and fatigue.
The oil is also a popular ingredient in the personal care and cleaning industries due to its strong, pleasant fragrance. It is incorporated into soaps, perfumes, and deodorants for its refreshing scent and ability to mask unpleasant odors. Research indicates that citronella oil possesses antifungal and antibacterial properties, leading to its inclusion in some topical formulations and cleaning agents. Note that the plant and its essential oil can be toxic to pets if ingested, potentially causing gastrointestinal upset or more severe symptoms.
Maximizing Repellency Through Proper Placement and Care
To maximize the limited deterrent properties of the live citronella plant, strategic placement and proper care are necessary. The plant thrives best in full sun, requiring at least six to eight hours of direct sunlight each day to grow vigorously and produce aromatic foliage. It should be planted in well-draining soil, as it is highly susceptible to root rot if left in waterlogged conditions. Overwatering should be avoided; the soil should be allowed to dry out significantly between waterings.
Strategic placement is crucial for leveraging the plant’s scent potential in outdoor areas. Plants should be situated near high-traffic zones, such as seating areas, entryways, or along the edges of patios. Positioning them where people or pets are likely to brush against them encourages the release of the fragrant oils. Regular pruning encourages bushier growth, creating more foliage to release the desired scent when disturbed.