The plant commonly sold as the “citronella plant” is typically a scented geranium, often a hybrid of Pelargonium citrosum, rather than the true citronella grass (Cymbopogon nardus). This perennial is prized for the strong, lemon-like fragrance released when its leaves are brushed or crushed, a scent many people associate with repelling insects. While its effectiveness as a mosquito repellent is often overstated, its attractive, deeply-lobed foliage and ease of care make it a popular choice for warm-weather containers. Because this scented geranium is not cold-hardy, keeping it alive year-round requires specific, consistent care, especially concerning its environmental needs and preparation for winter.
Light, Soil, and Water Requirements
The citronella geranium requires a significant amount of light to maintain a dense, bushy shape and robust health. Placing the plant in a location that receives full sun, meaning six or more hours of direct sunlight daily, is generally ideal during the growing season. If the plant is grown indoors, a south- or west-facing window is necessary to provide the required intensity, as insufficient light will cause the stems to become long and sparse in a condition known as legginess. In regions with extremely intense summer heat, providing a touch of afternoon shade can prevent the leaves from scorching while still ensuring the plant gets ample morning sun.
Proper soil composition must guarantee excellent drainage, as the plant is highly susceptible to root rot in boggy conditions. A standard, high-quality potting mix should be used, but it must be amended with materials like perlite, coarse sand, or bark chips to increase permeability. Using a container made of terracotta or another porous material can further assist by wicking excess moisture away from the soil and roots.
The plant prefers to dry out slightly between watering sessions. A good rule of thumb is to check the soil moisture by inserting a finger about two inches deep, and only watering when the soil feels completely dry at that depth. When watering, do so thoroughly until the water flows freely from the drainage holes, then discard any excess water that collects in the saucer. Overwatering is the single most common cause of decline, so reducing the frequency of irrigation is necessary during cooler or cloudy periods.
Pruning and Pest Management
Regular pruning encourages the plant to develop a compact, full structure instead of growing long, weak stems. Early in the growing season, pinch back the tips of young stems, removing about one-half inch just above a leaf node. This action stimulates the plant to branch out, creating a much bushier appearance. Older plants can be trimmed more aggressively for shaping and rejuvenation, especially when preparing them for an indoor transition or after a period of winter dormancy.
During the active growing period of spring and summer, the plant benefits from light, consistent feeding. Apply a balanced liquid fertilizer that has been diluted to half-strength every four to six weeks. Reduce or stop fertilization completely outside of the main growing season, as the plant’s nutritional needs drop significantly when growth slows.
Whiteflies and spider mites are the most frequent visitors and tend to congregate on the undersides of leaves. A simple, non-chemical treatment involves using a strong jet of water to physically dislodge the pests from the foliage. For more stubborn infestations, an application of insecticidal soap can be used to treat the affected areas, following the product’s instructions carefully to ensure full coverage.
Overwintering for Year-Round Survival
Since the citronella geranium is a tender perennial, it cannot survive freezing temperatures and must be brought indoors before the first frost, typically when nighttime temperatures consistently fall below 50°F. Before moving the plant inside, it is necessary to inspect it thoroughly for any lurking pests, which should be treated immediately to prevent them from spreading to other indoor plants.
One effective method for survival is to store the plant in a state of true dormancy, which is ideal if you lack a sunny indoor space. Begin this process by cutting the stems back significantly, removing most of the foliage. Next, remove the plant from its container and gently shake off the excess soil until only the bare roots remain. These bare-root plants should be stored in a cool, dark, and dry location, such as a basement or garage, where the temperature stays consistently between 35°F and 45°F.
Alternatively, the plant can be kept actively growing indoors throughout the winter as a houseplant, provided a spot with sufficient bright light is available. In this scenario, place the plant in the sunniest window possible, such as one facing south, and significantly reduce watering frequency. Keeping the indoor temperature cooler, ideally in the 55°F to 60°F range, helps to curb the rapid, weak growth that often leads to a leggy plant indoors.