The citronella plant (Pelargonium citrosum), known as the “mosquito plant,” is cultivated for its aromatic, citrus-scented foliage. It is popular for outdoor spaces. Understanding its temperature needs is important for successful growth.
Optimal Growing Temperatures
Citronella plants thrive in warm, consistent temperatures, reflecting their tropical origins. The ideal range for robust growth is 50°F to 80°F (10°C to 27°C). This range supports vigorous growth, fragrant leaves, and overall plant health.
Citronella’s Cold Tolerance and Overwintering Strategies
Citronella plants are tender perennials, susceptible to cold temperatures and frost. They are hardy in USDA Zones 9 to 11, remaining outdoors year-round. In colder climates, they are grown as annuals or brought indoors for protection.
The lowest temperature a citronella plant tolerates without significant damage is around 32°F (0°C). Extended periods below 50°F (10°C) cause stress; freezing temperatures are fatal. To overwinter container-grown plants, move them indoors when nighttime temperatures consistently drop below 45°F (7°C).
Before moving indoors, prune stems back by one-third, cutting just above a leaf node. This maintains health and encourages new growth. Indoors, provide ample direct sunlight (ideally six hours daily) from a south or west-facing window. Reduce watering, allowing soil to dry slightly between waterings to prevent root rot, as metabolic activity slows.
Citronella’s Heat Tolerance and Summer Care
Citronella plants handle high temperatures well, preferring full sun for at least six hours daily. However, intense summer heat above 90°F (32°C) can cause heat stress, including leaf scorching or wilting if water is insufficient.
To mitigate heat stress, provide afternoon shade in scorching sun. Consistent watering is important in hot climates, as water needs increase with higher temperatures. Keep soil consistently moist but not waterlogged to manage heat effectively.
Identifying and Addressing Temperature Stress
Recognizing temperature stress allows for timely intervention. Cold stress manifests as wilting, blackening leaves, or leaf drop. Foliage may appear limp, turn dark, or fall off.
Heat stress can cause wilting, yellowing leaves, or a crispy texture at leaf edges. Leaves may roll or cup to minimize moisture loss. If a plant wilts during the hottest part of the day but recovers by evening, it is likely heat stressed. To aid recovery, move the plant to a location with appropriate temperatures, adjust watering for consistent moisture, and prune damaged foliage to encourage new growth.