Plumbago (Plumbago auriculata), also known as Cape Plumbago or sky flower, is a tropical shrub with delicate blue flowers that bloom continuously from spring through fall. While it can reach 15 feet tall in its native South Africa, its adaptable nature makes it an excellent choice for container gardening. Growing plumbago in pots offers portability, allowing movement for optimal light or protection from harsh weather. This method also helps manage its sprawling growth, keeping it more compact.
Selecting the Right Pot and Potting Mix
Choosing an appropriate container is the first step towards a thriving potted plumbago. The pot should be large enough to accommodate its root system, with mature plants generally benefiting from a 12 to 16-inch diameter container. Terracotta pots are porous and allow the soil to breathe, though they dry out more quickly. Plastic or fiberglass pots retain moisture longer and are lighter. Proper drainage is essential; the chosen pot must have drainage holes at the bottom to prevent waterlogging, which can lead to root rot. A well-draining, fertile potting mix is crucial for healthy growth. Amend a standard potting mix with 10-20% perlite or coarse sand to enhance drainage and aeration.
Essential Daily Care
Light Requirements
Plumbago thrives in bright conditions, requiring ample sunlight to produce its abundant blooms. Full sun exposure, meaning at least six hours of direct sunlight daily, is ideal for optimal flowering. While the plant can tolerate partial shade, particularly in regions with intense summer heat, flowering may be less prolific in such conditions. In extremely hot climates, providing some afternoon shade can prevent leaf scorching and stress.
Watering Needs
Consistent moisture is important for potted plumbago, though overwatering must be avoided to prevent root issues. Water when the top 1 to 2 inches of soil feel dry to the touch. Water thoroughly until it drains from the bottom of the pot. During hot periods, daily moisture checks may be necessary as potted plants tend to dry out more quickly.
Fertilizing
Potted plumbago benefits from regular fertilization throughout its active growing season to support continuous blooming. A general-purpose fertilizer formulated for flowering plants is suitable. Fertilization can begin in spring and continue through summer and autumn. During the cooler, dormant months, feeding should be reduced or withheld entirely, as the plant’s growth slows down.
Pruning and Training
Regular pruning helps maintain the desired shape and size of potted plumbago, encouraging bushier growth and more flowers. Deadheading spent flowers throughout the growing season prompts the plant to produce new blooms. Light trimming can be done as needed to shape the plant, while more significant pruning to manage overall size is best performed in late winter or early spring before new growth emerges. Plumbago has a sprawling, somewhat vine-like habit, and its stems can be trained on a trellis or stake to encourage vertical growth.
Overwintering
For gardeners in colder climates (USDA zones 8 and below), overwintering potted plumbago is necessary to protect it from freezing temperatures. When temperatures consistently drop below 50°F, the plant should be moved indoors to a protected location.
There are two main approaches: treating it as a houseplant or allowing it to go dormant. If kept as a houseplant, provide a brightly lit room or supplement with grow lights, and reduce watering frequency. For dormancy, prune the plant back in late autumn and store it in a cool, dark, and frost-free area, such as an unheated garage or basement, with minimal watering. Once consistent temperatures above 50°F return in spring, the plumbago can be gradually transitioned back outdoors.