The citronella plant, commonly Pelargonium citrosum, is known for its lemon-scented foliage and association with mosquito deterrence.
Optimal Growing Temperatures
Citronella plants thrive best within a temperature range of 50°F to 80°F (10°C to 26°C). This spectrum supports vigorous growth and encourages the production of their characteristic fragrant oils. They benefit from at least six hours of sunlight daily, ideally with cooler morning sun and some afternoon shade to prevent overheating. Humidity levels between 40% and 70% also contribute to their well-being.
Cold Tolerance and Winter Care
The citronella plant is highly sensitive to cold temperatures and cannot survive frost. Damage occurs when temperatures consistently dip to 45°F (7°C) or lower, leading to wilting. As a tender perennial, it is hardy only in USDA Zones 9 through 11, where it can remain outdoors year-round. In colder regions (Zone 8 and below), treat it as an annual or bring it indoors to overwinter.
To protect citronella plants from freezing temperatures, move potted specimens indoors before the first frost or when nighttime temperatures consistently fall below 45°F. Once inside, place the plant in a bright location, such as a south or west-facing window, ensuring it receives several hours of direct sunlight. During its indoor period, reduce watering frequency, allowing the soil to dry out between applications to prevent root rot. Pruning leggy or woody stems helps the plant maintain a compact shape and encourages bushier growth when returned outdoors in spring.
Heat Tolerance and Summer Care
Citronella plants generally exhibit good heat tolerance, capable of withstanding temperatures reaching into the high 90s°F (30s°C). They are considered drought-tolerant once established in the ground, though potted plants require more consistent moisture. Despite their sun-loving nature, prolonged exposure to intense, direct afternoon sun in very hot climates can lead to heat stress.
Signs of heat stress may include wilting, browning or scorching of leaf tips and edges, and sometimes a general yellowing of the foliage. To mitigate these issues, provide partial shade during the hottest parts of the day, especially in southern zones with intense summer heat. Adequate watering is important; check the top inch or two of soil and water thoroughly when it feels dry. Ensuring proper air circulation around the plant, particularly in humid conditions, can help it manage high temperatures effectively.