The Citronella plant is a popular choice for gardeners seeking a fragrant, leafy addition to patios and outdoor spaces. Its characteristic lemon-like scent often makes it a sought-after plant for placement near seating areas. Understanding the mature dimensions of this fast-growing herb is necessary for choosing the right location and container size.
Understanding the Two Plants Called Citronella
The name “Citronella Plant” commonly refers to two distinct species, which often leads to confusion regarding expected mature size. The plant most widely sold in garden centers, and often labeled as the Mosquito Plant, is the scented geranium, Pelargonium citrosum. This species is a tender perennial sub-shrub with lacy, fragrant leaves. It is often grown as an annual in temperate climates, where it only reaches a fraction of its potential size before the season ends.
The true botanical source of commercial citronella oil is a tall, tropical grass, Cymbopogon nardus, known as Citronella Grass. This grass has a vastly different growth habit and scale compared to the geranium. Because the Pelargonium citrosum is the most common variety grown in home containers, the following dimensions focus on this popular, shrub-like plant.
Standard Height and Spread
The common Pelargonium citrosum typically achieves a moderate size, making it suitable for both garden beds and large containers. The average mature height for this plant falls between 2 and 3 feet (60 to 90 centimeters) in a single growing season. Its spread is comparable, ranging from 1 to 2 feet wide, giving the plant a bushy, rounded form. Some varieties and plants grown in ideal, perennial conditions can reach up to 4 feet in height and spread, showcasing a more substantial shrub-like habit.
Growth is significantly influenced by the planting method, especially in colder regions where the plant is grown as an annual. When planted directly in the ground in warm zones, where it acts as an evergreen perennial, the plant can reach its maximum dimensions more easily. For container planting, which is common for seasonal display, the plant’s size is naturally restricted by the volume of the pot. A container at least 12 inches deep is recommended to allow for a healthy, 2-foot tall specimen.
The plant’s growth rate is fast, meaning it can reach its full seasonal height and spread relatively quickly. If the plant is overwintered indoors, it retains its woody structure and resumes growth in the spring, potentially leading to a larger, more established specimen over multiple years.
Managing Growth Through Pruning and Environment
Gardeners can influence the final size and shape of the Pelargonium citrosum through pruning practices. The most effective way to encourage a compact, dense plant rather than a tall, leggy one is through regular pinching. Removing the growing tips of the stems, often called pinching, encourages the plant to branch out laterally. This results in a bushier silhouette and helps to keep the overall height in check.
Pruning can be done throughout the growing season, but a substantial cutback in late winter or early spring stimulates healthy new growth just before the main growing period. Cutting stems back to just above a leaf node promotes regeneration and maintains the desired framework. For plants that have become overgrown or woody by the end of the season, a heavy pruning is often necessary, especially before bringing the plant indoors to overwinter.
Environmental factors also play a substantial role in determining the plant’s size. Placing the plant in a location that receives full sun encourages denser foliage and a more robust growth habit. Container-grown plants require more frequent watering and fertilization compared to those in the ground, due to the limited soil volume. Providing ample light, water, and nutrients allows the plant to reach the upper end of its size range, while reducing these resources can naturally restrict its growth.