The plant commonly marketed as the “Mosquito Plant” or Citrosa Geranium is botanically known as Pelargonium citrosum ‘Van Leenii’. This cultivar is a fragrant, scented geranium known for its deeply lobed, lace-like foliage and a pronounced citrus aroma. Its popularity stems from the widespread claim that its scent naturally repels mosquitoes, making it a desirable addition to outdoor spaces. Understanding the specific cultural needs of this plant is key to successful cultivation, whether grown for fragrance or as an attractive ornamental.
Essential Growing Conditions
The Mosquito Plant thrives with ample light, requiring a minimum of six hours of direct sunlight daily to maintain dense, vigorous growth. Outdoors, position the plant to receive morning sun and protection from intense afternoon heat, especially in hot climates, to prevent leaf scorch. Indoor plants need the brightest window available, such as a south or west-facing exposure, to prevent stems from becoming thin and stretched.
The plant’s root system is sensitive to excessive moisture, so a well-draining soil mix is essential for its health. A standard commercial potting mix is suitable, but incorporating amendments like perlite, coarse sand, or orchid bark will significantly improve drainage. These amendments should constitute about 20% of the mix. Water the plant thoroughly only after the top inch or two of the soil has completely dried out, ensuring excess water drains freely from the pot’s bottom. Reduce watering frequency during cooler winter months when the plant’s growth naturally slows.
Ongoing Care and Maintenance
During the active growing season, from spring through early fall, fertilization supports rapid growth and dense foliage. Apply a balanced liquid fertilizer diluted to half-strength approximately once every four to six weeks. Over-fertilizing can lead to weak, overly lush growth, so follow the product’s application rates carefully.
Regular pruning maintains a compact, bushy shape and maximizes the surface area of the fragrant leaves. Pinching back the stem tips encourages the plant to branch out laterally, creating a fuller appearance. Removing spent flower stalks and faded blooms, known as deadheading, redirects the plant’s energy toward foliage production rather than seed development.
The Mosquito Plant is not tolerant of freezing temperatures and is typically grown as an annual in most climates, surviving only in USDA Hardiness Zones 9 through 11. To keep the plant perennial, it must be brought indoors before nighttime temperatures consistently drop below 45°F to 50°F. When winterizing, place the plant in a cool, bright location and drastically reduce watering to allow it to enter a semi-dormant state until spring arrives.
Propagation Techniques
Creating new Mosquito Plants is easily accomplished using stem cuttings, a process best performed during the spring or summer growing months. Select a healthy, non-flowering stem and use clean, sharp shears to take a cutting three to four inches long that includes at least two leaf nodes. New roots will form at the node, which is the small bump on the stem where a leaf emerges.
After taking the cutting, carefully remove the lower leaves, leaving only the top two or three intact to minimize moisture loss. Dipping the cut end into a powdered rooting hormone is optional, but it can significantly increase the success rate of root development. Insert the prepared cutting into a small pot filled with a sterile, moist, and well-draining propagation medium, such as a mix of perlite and peat moss. Place the pot in bright, indirect light and maintain high humidity to encourage roots to form within three to four weeks.
Understanding the Repellent Claim
The appealing citrus aroma of the Mosquito Plant is due to the presence of volatile oils, including citronellol, geraniol, and linalool, found within the leaf tissue. This scent is only released when the leaves are physically crushed or brushed against, which breaks the oil glands on the leaf surface. The intact, potted plant does not continuously emit enough fragrance into the surrounding air to act as a barrier against insects.
Despite common marketing, numerous scientific studies have demonstrated that simply placing the potted plant nearby provides virtually no effective protection against mosquito bites. Field tests comparing the plant’s effect to untreated control groups have shown no significant difference in the number of mosquito landings or bites. The plant’s reputation as a mosquito repellent is largely unfounded, making its primary value purely ornamental and aromatic. To utilize the scent, a person must actively crush the leaves and rub the oils onto their skin, a practice that offers only minimal and short-lived protection compared to commercial topical repellents.