Ruellia simplex, commonly known as Mexican Petunia or Mexican bluebell, is a tender perennial valued for its rapid growth and continuous display of trumpet-shaped flowers in shades of purple, pink, or white. While this plant provides an easy way to fill garden spaces quickly, its aggressive nature means it can spread rapidly through the landscape. Learning to propagate this species allows gardeners to manage its spread by relocating or sharing new plants, or to intentionally fill specific areas. Successful propagation is easily achieved through several straightforward methods, making it simple to multiply your stock.
Propagating Through Stem Cuttings
Propagating Mexican Petunia using stem cuttings is an effective method for producing new, genetically identical plants. The optimal time to take these cuttings is during the plant’s active growth period, typically in the spring or early summer. Select a healthy, non-flowering stem section about four to six inches long and use a sharp, clean cutting tool to make the cut just below a leaf node, as this is where the new roots will emerge.
After taking the cutting, carefully strip off the lower leaves, leaving only two or three sets at the top to reduce moisture loss. Dipping the cut end into a rooting hormone powder can significantly increase the success rate and speed of root formation. Insert the prepared cutting into a small pot filled with a sterile, well-draining potting mix, such as a blend of peat moss and perlite. Place the potted cutting in a warm location that receives bright, indirect light, ensuring the medium remains consistently moist but not waterlogged.
Creating a humid environment, perhaps by covering the pot with a clear plastic bag, helps the cutting focus its energy on growing roots. Within a few weeks, tugging gently on the stem will reveal resistance, indicating that new roots have begun to anchor the plant. The emergence of new leaf growth is the visual sign that propagation has been successful and the new plant is ready for the next stage.
Propagating Through Root Division
Root division offers a robust method for propagating Mexican Petunia, particularly when managing or reducing the size of an established, mature clump. This technique is best performed in the early spring before new seasonal growth begins or in the fall after the flowering season has ended. The plant’s rapid spread is facilitated by its rhizomatous root system, which consists of horizontal underground stems that produce new shoots.
To divide the plant, use a garden fork to carefully loosen the soil around the parent plant and lift the entire root ball from the ground. Use a sharp spade or a clean knife to cut the root mass into smaller sections. Ensure that each new division contains a portion of the roots and at least a few healthy stems or shoots.
The newly separated sections should be replanted immediately into their new location at the same depth they were previously growing. Dividing established plants helps to manage their potentially overwhelming presence in a garden bed and provides a quick way to gain robust, ready-to-grow clones.
Transitioning New Plants to the Garden
Once the cuttings have developed a solid root system or the divisions have been cleanly separated, the next step involves planting them into their final garden position. For cuttings started in a protected environment, a process of gradual acclimatization, known as hardening off, is beneficial before permanent planting. This involves slowly increasing their exposure to direct sunlight and wind over a period of about a week to reduce the shock of being moved outdoors.
Mexican Petunia thrives in a wide range of light conditions, performing best and producing the most flowers in full sun, though it will tolerate partial shade. The newly planted material requires consistent moisture to establish its roots. Water thoroughly after planting and maintain an evenly moist soil profile for the first few weeks.
Given the plant’s natural vigor, it rarely requires heavy fertilization, though a light application of a balanced granular fertilizer in the spring can support lush growth. When selecting the planting site, be mindful of the plant’s potential to spread via its rhizomes; some gardeners choose to plant it in containers or use root barriers to help confine its growth. Providing adequate space between plants, roughly two to three feet, helps ensure good air circulation and reduces the likelihood of overcrowding.