The term “citronella plant” refers to plants known for their distinctive aroma, but their size can vary considerably. Understanding what determines this variation is important for gardeners. This article explores the different plants commonly referred to as “citronella plants” and the factors influencing their growth and dimensions.
Understanding the “Citronella Plant”
The term “citronella plant” refers to two distinct botanical groups. One is Pelargonium citrosum, often marketed as the “Mosquito Plant” or “Citronella Geranium,” which exhibits a shrub-like growth habit. The other encompasses Cymbopogon species, such as Cymbopogon nardus (true Citronella Grass) and Cymbopogon citratus (Lemongrass), which are true grasses. Both types have a lemon-like scent, but Cymbopogon is the primary source of citronella essential oil. These two plant types differ in growth patterns and size, leading to varied cultivation needs.
Size of Pelargonium citrosum (Mosquito Plant)
Pelargonium citrosum, often called the Mosquito Plant or Citronella Geranium, grows as an herbaceous annual in most climates due to frost sensitivity. In warmer USDA Zones 9-11, it can be a perennial sub-shrub, developing a woody base. This plant generally reaches 1 to 3 feet tall and spreads 1 to 3 feet wide, though some sources indicate a more compact spread of 12-18 inches. Its upright, spreading habit makes it suitable for containers or as a groundcover.
In containers, Pelargonium citrosum remains compact, suitable for indoor spaces with sufficient light. Its growth rate is fast, establishing quickly within a growing season. Even when planted in the ground in suitable climates, its size rarely exceeds 3 feet. This plant is valued for its fragrant, ferny foliage and occasional violet flowers, adding to its appeal.
Size of Cymbopogon Species (Citronella Grass)
Cymbopogon species, including Cymbopogon nardus (true Citronella Grass) and Cymbopogon citratus (Lemongrass), are tropical, clump-forming perennial grasses. These plants are larger than Pelargonium citrosum, typically reaching 4 to 6 feet tall, and sometimes up to 8 feet in ideal conditions. They spread 2 to 5 feet wide, forming dense, clumping mounds.
Cymbopogon citratus can grow 2-4 feet tall and 2-3 feet wide, while Cymbopogon nardus often reaches 5-8 feet tall and 3-5 feet wide. These grasses are best suited for planting in the ground where they have ample space, or in very large containers to accommodate their extensive root systems. Their rapid growth rate allows them to form large specimens within a single growing season, especially in warm, humid conditions. They are perennial in tropical and subtropical regions (USDA Zones 9-12), but often grown as annuals or overwintered indoors in cooler climates due to frost sensitivity.
Factors Influencing Citronella Plant Size
The size of both Pelargonium citrosum and Cymbopogon species is influenced by several environmental and cultivation factors. Consistent access to adequate light is important; full sun (6-8 hours daily) promotes growth. Insufficient light can lead to leggy, weaker growth and a reduced overall size.
Water and soil conditions also play a role in plant development. Both types thrive in moist, well-draining soil, with Cymbopogon species benefiting from consistent moisture. While some drought tolerance can develop, prolonged dryness or waterlogging can stunt growth and limit size. Providing adequate nutrients through a balanced fertilizer, especially during the active growing season, supports growth and larger plant size.
For container plants, pot size directly impacts growth. A small pot restricts root development, limiting the plant’s potential size and leading to stunted growth. Choosing a container that allows for root expansion helps maximize plant size. Regular pruning can manage plant size and shape. Trimming back stems encourages bushier growth, allowing gardeners to maintain a desired form and size for their plants.