Plumbago auriculata, or Cape Plumbago, is an evergreen shrub known for its sprawling habit and blue, phlox-like flowers. Native to South Africa, it offers a long blooming season and easy care. Its vibrant color and ability to attract pollinators make it a valued choice for various landscape settings.
Growing and Caring for Plumbea
Cape Plumbago thrives in full sun, ideally six or more hours daily. While it adapts to partial shade, flowering is reduced. Container plants overwintered indoors require a brightly lit room.
This plant performs well in fertile, well-draining soil, adapting to various soil types. A slightly acidic to neutral pH (6.1 to 7.3) is ideal for optimal growth. Higher alkalinity, especially above pH 7.3, can cause yellowing leaves, indicating deficiencies.
Regular watering is important, especially during establishment. Aim for one inch of water per week for best performance. Once established, the plant tolerates drought, though consistent moisture promotes the best display. Allow the soil to dry slightly between waterings to prevent root rot.
Cape Plumbago is evergreen in USDA hardiness zones 8 through 11. It tolerates temperatures down to 25°F before foliage damage occurs, and roots are hardy to 10°F. Temperatures above 60°F promote vigorous growth, though extreme heat can fade flower colors. In colder climates, move container plants indoors when temperatures drop below 50°F.
To support vigorous growth and continuous flowering, fertilize Cape Plumbago twice annually with a balanced 10-10-10 slow-release fertilizer. Apply in early spring and autumn. Liquid fertilizers can be applied every two weeks from April to September. Avoid excessive fertilization, which can cause root burn; water thoroughly after application.
Pruning Plumbea
Pruning Plumbago auriculata maintains shape, promotes bushiness, and encourages flowering. Since flowers form on new growth, strategic pruning maximizes bloom production. This vigorous plant can become leggy, so regular trimming keeps it compact and aesthetically pleasing.
Extensive shaping is best done in late winter or early spring before new growth. Throughout the growing season, deadhead spent flower clusters to encourage more blooms and extend flowering. Remove crossing, diseased, or damaged stems at any time.
Propagating Plumbea
Cape Plumbago propagates well from stem cuttings, especially softwood or semi-hardwood. Take healthy, non-flowering shoots 4 to 6 inches long during the active growing season. Remove terminal buds and lower leaves, leaving only the top one or two sets.
Dip the cut end in water, then rooting hormone, before inserting into a well-draining potting medium. A mixture of potting soil with sand, perlite, or vermiculite works. Keep the soil consistently moist and place cuttings in bright, indirect light. Roots typically form within weeks, allowing transplant once established.
While less common for home gardeners, Cape Plumbago can also be grown from seed. Sow seeds in early spring in a warm location (72-75°F) with consistent moisture. Germination usually occurs within 7 to 10 days, but can take 4 to 6 weeks. Seed-grown plants may take up to two years to flower.
Addressing Plumbea Problems
Cape Plumbago generally has few pest or disease issues, but problems can arise. Common pests include aphids, whiteflies, and spider mites, especially on indoor plants. Regularly inspect for infestation signs, and consider organic control methods like insecticidal soap if pests are present.
Fungal issues like powdery mildew can occur, particularly in humid conditions. Ensure good air circulation and avoid overhead watering to prevent such diseases. Environmental stressors often cause visible changes. Yellowing leaves can indicate overwatering, underwatering, or a lack of essential nutrients, especially if soil pH is too alkaline.
Insufficient light is a common reason for poor flowering, as it requires ample sunlight. Wilting foliage signals a need for water, while a lack of new growth may suggest a need for fertilization or improved conditions. Addressing these environmental factors promptly restores plant health.
Plumbea in Your Garden
Plumbago auriculata offers various landscaping uses due to its adaptable growth habit and long-lasting blooms. It can be cultivated as a sprawling shrub, trained as a climbing vine with support, or used as a cascading groundcover. Its ability to fill spaces makes it suitable for hedges or mass plantings.
The plant’s profusion of sky-blue flowers, blooming from spring through fall, adds continuous color and attracts pollinators. It is also popular for container planting, allowing gardeners in colder zones to bring it indoors during winter.
Cape Plumbago has mild toxic properties if ingested. It can also cause skin irritation upon contact, so wearing gloves when handling or pruning is advisable. The fruit capsules have sticky barbs, which can adhere to clothing if placed too close to pathways.