Many gardeners wonder if “citronella plants” return each year. These fragrant plants are popular additions to outdoor spaces. Understanding their nature and needs clarifies expectations for their yearly appearance. This article explores factors determining if your citronella plant will come back.
Understanding Citronella Plant Hardiness
The term “citronella plant” often refers to two distinct botanical species, each with different hardiness characteristics. The plant commonly sold as a “citronella plant” or “mosquito plant” is typically a scented geranium, Pelargonium citrosum ‘Citrosum’. This tender perennial is hardy in USDA Zones 9 through 11, where temperatures rarely drop below freezing. In colder winters, it is usually grown as an annual, dying back with the first hard frost.
True citronella grass (Cymbopogon nardus or Cymbopogon winterianus) is a different plant. This tropical perennial grass is much larger and significantly more sensitive to cold than the scented geranium. It thrives only in USDA Zones 10 through 12, where temperatures stay above freezing. Outside these regions, it is almost always cultivated as an annual, as it cannot tolerate frost or prolonged cold.
Factors Affecting Citronella Plant Survival
Several environmental conditions dictate whether a citronella plant, particularly the scented geranium, will survive colder months. Sustained freezing temperatures are a threat, as prolonged exposure to cold can damage plant cells and root systems. Even in theoretically hardy zones, a harsh cold snap can prove fatal.
Frost exposure, especially for container plants, can also significantly impact survival. Potted plants have less root insulation than those in the ground, making them more vulnerable to freezing. Winter soil moisture is another factor; overly wet soil, combined with cold, can lead to root rot and plant demise. Poor drainage exacerbates this issue by preventing water from moving away from roots. Microclimates, like sheltered spots near a building, offer some protection but do not guarantee survival against severe cold.
Winterizing Your Citronella Plant
To help your citronella plant, especially scented geraniums, survive the winter, several practical steps can be taken. For potted plants, bring them indoors before the first frost. Place them in a bright, sunny window and reduce watering, allowing the soil to dry between waterings. This encourages a period of semi-dormancy, helping the plant conserve energy indoors.
For scented geraniums in the ground in borderline zones, apply a thick layer of mulch around the base to insulate roots. Another strategy is taking cuttings in late summer or early fall. These can be rooted in water or soil indoors and grown as houseplants over winter. True citronella grass, due to its size and tropical nature, is rarely overwintered outside its hardy zones and is typically grown as an annual in most climates.
Assessing Spring Revival
As spring approaches, gardeners will look for signs of life from their overwintered citronella plants. New shoots emerging from the base of the plant or green growth appearing along seemingly dormant stems are clear indicators of revival. This new growth typically begins after the last frost and as temperatures consistently warm.
It is helpful to wait a few weeks into the spring growing season before assuming a plant is dead, as some plants may take longer to show signs of life. Once new growth is visible, prune away any dead, brittle, or brown stems from the previous season. This improves appearance and directs energy towards healthy new foliage.