Do citronella plants actually flower, and does it matter for their primary purpose? The answer depends on which specific plant is referenced, as many are marketed under this popular name, leading to confusion. Understanding these distinctions helps clarify their flowering habits and how these might relate to their perceived benefits.
Understanding the “Citronella Plant”
The term “citronella plant” often causes misunderstanding. Two distinct plant types are commonly referred to by this name: Pelargonium citrosum, a scented geranium marketed as the “mosquito plant,” and true citronella grasses (Cymbopogon nardus or Cymbopogon winterianus). Both plants contain compounds with similar aromatic properties, contributing to their association with citronella.
Pelargonium citrosum is a hybrid plant with deeply lobed, fragrant leaves. It was developed to mimic the scent of citronella. In contrast, Cymbopogon nardus and Cymbopogon winterianus are actual grass species native to tropical and subtropical regions of Asia. These grasses are the primary commercial sources for citronella oil.
Flowering of Scented Geraniums
Pelargonium citrosum, the scented geranium commonly sold as a “citronella plant,” does flower. These blooms are small and inconspicuous, appearing in shades of light pink to lavender or white, sometimes with darker markings on the upper petals. They usually emerge in clusters on slender stalks above the foliage.
Flowering occurs during warmer months, from late spring through summer. However, these flowers are not the primary reason gardeners cultivate Pelargonium citrosum. The plant is primarily grown for its fragrant foliage, which releases a citrusy aroma when brushed or crushed. The presence or absence of these flowers does not significantly alter the plant’s main appeal.
Flowering of True Citronella Grass
True citronella grasses, Cymbopogon nardus and Cymbopogon winterianus, also produce flowers, though they are far less showy than those of scented geraniums. As grasses, their inflorescences are typical. They form tall, slender flower stalks that emerge from the dense clumps of foliage. These stalks bear small, feathery seed heads, appearing as inconspicuous spikelets.
Flowering usually occurs in warmer climates or towards the end of the growing season. The appearance of these flower stalks indicates the plant is reaching maturity. Unlike ornamental plants, their flowers are not cultivated for aesthetic appeal. Their primary function is seed production, ensuring propagation.
Flowering and Mosquito Repellency
The primary interest in “citronella plants” is their potential for mosquito repellency. For both Pelargonium citrosum and true citronella grasses, the compounds responsible for their aromatic properties, such as citronellal, geraniol, and citronellol, are concentrated in the leaves and stems, not the flowers. These volatile compounds are released when the foliage is disturbed, such as when leaves are crushed or brushed against.
Therefore, the presence or absence of flowers does not significantly impact mosquito deterrence. The repellent effect stems directly from the oils within the vegetative parts of the plant. To release these aromatic compounds effectively, direct interaction with the leaves is required.
Caring for Citronella Plants When They Flower
When Pelargonium citrosum begins to flower, gardeners can choose to deadhead the spent blooms. Deadheading, removing faded flowers, redirects the plant’s energy from seed production to foliage growth. This encourages a bushier plant and potentially more fragrant leaves. While not strictly necessary for health, it can improve appearance and promote vegetative growth.
For true citronella grasses, flower stalks typically signify the end of the growing season or maturity. These stalks can be left or pruned. Pruning helps maintain tidiness and encourages foliage production over seeds. Neither plant type is harmed by flowering, but managing blooms optimizes the plant for its purpose.