The citronella plant, commonly sold for its lemon-scented foliage, is typically a type of scented geranium, Pelargonium citrosum, rather than true citronella grass (Cymbopogon nardus). Growing this plant in a container requires careful consideration of the pot size to manage its fast-growing root system and ensure maximum production of the aromatic oils. The container’s size directly affects the soil volume, which in turn regulates moisture levels, profoundly impacting the plant’s health and vigor. Selecting the correct pot and following a planned repotting strategy prevents common issues like root rot and stunted growth.
Choosing the Initial Container Size
When purchasing a young Pelargonium citrosum, it is usually housed in a small 4-inch or 6-inch diameter pot. The goal is to transition the plant to a container that provides space for growth without holding excessive moisture. The new pot should only be 1 to 2 inches larger in diameter than the existing root ball; for example, a 4-inch nursery plant should move to a 6-inch container.
Starting with a pot that is too large, such as a 10-inch container, can cause problems because the small root mass cannot efficiently absorb water. The excess, saturated soil remains wet for too long, creating an anaerobic environment that often results in root rot. Conversely, a container that is too small will restrict the root system, slowing growth and diminishing the quality of the scented foliage. The initial pot size balances providing room for expansion while maintaining a healthy, fast-draining environment around the roots.
Repotting Strategy for Mature Growth
As the citronella plant grows, its root system will fill the current container, making repotting an annual or biennial necessity. A plant is considered root-bound when roots are circling the drainage holes or when water runs straight through the pot without soaking the soil. This condition restricts the plant’s access to water and nutrients, leading to slowed top growth.
When upsizing, select a new pot that is only 2 inches greater in diameter than the previous one. For instance, moving a plant from a 6-inch pot to an 8-inch pot prevents the water-retention issues associated with oversized containers. A mature, full-sized plant, which can grow up to two feet tall and wide, may ultimately require a container around 12 inches in diameter.
Repotting is ideally performed in the early spring as the plant begins its active growth cycle. If you wish to maintain the plant’s current size, you can prune the roots. Trim up to one-third of the root mass and cut back the top growth, allowing the plant to be returned to the same container with fresh soil.
Essential Container Features and Soil Medium
The physical characteristics of the container are nearly as important as its size, with drainage being the most important feature. The pot must have large, unobstructed drainage holes to ensure no water accumulates at the bottom, which prevents root rot. Any saucer used underneath the container must be emptied promptly after watering.
Container material affects moisture retention, making unglazed terra cotta pots a preferred choice over plastic. Terra cotta is porous, allowing water to evaporate through the walls, promoting air circulation, and helping the soil dry out quickly. Plastic pots retain moisture longer but can be used if watering is managed carefully and the soil mixture is well-draining.
The soil medium must be loose and highly permeable to support the plant’s aversion to wet roots. Standard potting soil should be improved by incorporating amendments to enhance drainage and aeration. A good blend consists of quality potting mix combined with up to 25% perlite, coarse sand, or pine bark fines to ensure excess water moves rapidly away from the root zone.