The plant often searched for as the “plethora plant” is commonly known as the Princess Flower or Glory Bush, belonging to the genus Pleroma (formerly Tibouchina). This ornamental shrub is native to the seasonally dry tropical regions of Brazil, and is highly valued for its continuous display of vibrant purple flowers. Cultivating this plant allows gardeners to introduce an exotic, year-round blooming specimen to warm climates or a container plant to cooler zones. Successful growth requires understanding its unique physical characteristics and providing the precise environmental conditions it needs to thrive.
Identifying the Plant
The Princess Flower is easily distinguished by its unique foliage and spectacular blooms, confirming its identity as Pleroma urvilleanum. The leaves are dark green, often four to six inches long, and covered in short, silky, silvery hairs, giving them a velvety texture. They also feature deeply set, prominent longitudinal veins.
The flowers are the plant’s signature feature, emerging in terminal clusters that provide color throughout the growing season. Each flower is large, typically three to four inches in diameter, displaying a rich, royal purple or magenta hue. The flowers are accented by long, curved stamens that are often blackish, creating a contrast against the petals.
In its native environment, Pleroma urvilleanum grows as a sprawling evergreen shrub, reaching heights of 10 to 20 feet. When grown outside of tropical zones, especially in containers, the plant maintains a more manageable size of three to six feet tall. If left unpruned, it may develop a rounded or slightly sprawling form over time.
Ideal Environment and Soil Needs
The correct light exposure is required for robust growth and prolific flowering. This tropical shrub prefers full sun, meaning at least six hours of direct sunlight daily to produce abundant blooms. In the hottest climates, providing filtered light or afternoon shade prevents the flowers and foliage from scorching.
Temperature is the primary constraint for outdoor cultivation. The plant is reliably hardy as a perennial only in USDA Zones 9 through 11, where frost is infrequent. In Zone 8, the plant may behave as a herbaceous perennial, dying back during winter but regrowing from the roots in spring. Gardeners in cooler climates should treat the Princess Flower as an annual or grow it in a container so it can be moved indoors before temperatures drop below 40°F.
The soil must be rich in organic matter and provide excellent drainage. A slightly acidic soil pH is preferred, ideally around 5.5 to 6.5, which facilitates nutrient uptake. Incorporating amendments like peat moss or compost helps achieve the necessary structure for drainage and the required lower pH level.
Ongoing Care and Seasonal Pruning
Maintaining consistent soil moisture is a continuous aspect of Princess Flower care, requiring regular watering throughout the active growing season. The goal is to keep the soil evenly moist, never allowing it to completely dry out, but also ensuring it is not waterlogged. Container-grown specimens, in particular, may need more frequent watering during hot summer periods, as the soil in pots tends to dry out more quickly.
Fertilization is routine during spring, summer, and early fall to fuel continuous flowering. Apply a balanced fertilizer, such as a 10-10-10 formula, every four to six weeks to support growth and blooming. Using a formula designed for acid-loving plants, like those for rhododendrons, also helps maintain the preferred slightly acidic soil conditions.
Pruning is essential for managing the plant’s size and encouraging a dense, bushy form. The optimal time for significant pruning is in late winter or early spring before new growth begins. The plant responds well to heavy cutting, which promotes bushier growth and more flower clusters. Deadheading spent blooms throughout the season redirects energy toward producing new flowers rather than setting seed.
Overwintering Container Plants
For plants grown in containers outside of hardiness zones, overwintering protects them from freezing temperatures. Bring the potted plant indoors to a bright location, such as a cool sunroom or a sunny window, before the first expected frost. While indoors, significantly reduce the watering frequency. This allows the plant to enter a semi-dormant state until it can be safely moved back outside in the spring.