Citronella plants, often recognized by their common name “mosquito plant” or “citronella-scented geranium,” are favored additions to outdoor living areas. These fragrant plants are widely appreciated for their distinctive lemon-like aroma, which is released when their leaves are brushed or crushed. Their popularity stems from the widespread belief in their ability to deter mosquitoes, making them a common choice for patios, decks, and garden borders. Understanding the plant’s temperature preferences is important for gardeners seeking to extend its presence beyond a single growing season.
Citronella Plant Cold Tolerance
The citronella plant (Pelargonium citrosum) is classified as a tender perennial, meaning it can survive multiple years in warmer climates. It thrives outdoors in USDA Hardiness Zones 9 through 11, where it can return each year and may even remain evergreen. In these regions, temperatures typically do not drop below freezing, allowing the plant to persist.
In areas outside these zones, where temperatures regularly fall below freezing, the citronella plant is generally cultivated as an annual. It struggles to endure cold weather and will not survive frost conditions. While some studies suggest survival at temperatures around 46.4 degrees Fahrenheit (8 degrees Celsius), this often results in reduced growth and productivity.
Protecting Citronella from Cold
Proactive measures can safeguard citronella plants from cold weather. In cooler zones, bringing potted plants indoors before the first frost is common. This transition should ideally occur when nighttime temperatures consistently drop to around 45-50 degrees Fahrenheit (7-10 degrees Celsius) to prevent cold shock. For plants in the ground in borderline zones, temporary covers, such as frost cloths or blankets, can offer some protection during unexpected cold snaps.
When overwintering indoors, select a location with ample light, such as a sunny window, or use a grow light if natural light is insufficient. Reduce watering frequency significantly during the cooler months, allowing the soil to dry out considerably between applications. Pruning back the plant before bringing it inside can also help manage its size and encourage healthier indoor growth.
Recognizing and Addressing Cold Damage
Cold damage on a citronella plant manifests in several ways. Symptoms include wilting or drooping leaves, followed by blackening or browning. Stems may also become softened or mushy, indicating more severe tissue damage.
Upon observing these signs, allow time for the plant to recover before taking drastic action. Once the threat of cold has completely passed, assess the damage by gently scraping the stem; if green tissue is visible beneath the outer layer, the plant may still recover. Prune away only the clearly dead or damaged parts, making cuts above a healthy leaf node, but avoid excessive pruning as this can further stress the plant. Refrain from fertilizing immediately, as the plant needs to focus its energy on recovery rather than new growth.