Imperial blue cape plumbago, (Plumbago auriculata) is a vigorously growing evergreen perennial. Also known as cape leadwort, cape plumbago and skyflower, this shrub exhibits vinelike tendencies. Plumbago plants bloom year-round in the tropics and in regions with temperate seasons. The abundant flowers of this plant range from white to deep blue. Blue cape plumbago attracts birds and butterflies. Plumbago flowers provide a nectar source, and act as a larval host, for several types of butterflies.
Plant imperial blue cape plumbago in an area that receives full sun to partial shade. It produces more blooms in direct sun. It prefers a well-draining, loamy, soil that is slightly sandy. To amend clay soil, mix a generous amount of organic matter and coarse sand into the soil. To amend soils with high sand content, mix a generous amount of organic matter into the existing soil. It performs best in soil slightly acidic soil with a 7.0 pH level. Thoroughly mix gardening lime into the soil to raise the pH level, or use sulphur to lower it.
Water the plant frequently until established. Once established, blue cape plumbago tolerates drought. This plant is frost-sensitive but rebounds quickly, even when it appears that a deep frost has completely killed it. The flowers are sticky because of the gland-tipped hairs on the petals. They fall off the plant easily; heavy tropical rains can strip an entire plumbago plant of flowers.
To prevent knocking the blooms off the plant, don't spray blooms directly with water. Fertilise with a water-soluble fertiliser every two weeks throughout the spring and summer between bloom flushes. Do not fertilise once the plant has flowered.
Blue cape plumbago grows quickly and has a tendency to vine. The plant quickly fills in large garden areas or climbs along a trellis. Imperial blue cape plumbago quickly reaches 10 feet in height and width. Wear garden gloves and a long-sleeve shirt when pruning; the flowers are very sticky and might stick to skin. Frequently prune to control the blue plumbago if compact shrubs are preferred. Do not worry about harsh pruning; it will generate new growth quickly.
A series of closely planted plumbago plants creates a whimsical hedge along sidewalks and driveways. It creates an extra splash of colour as a backdrop for flowerbeds. Flower buds develop on new growth, and each trimming results in another flush of blue flowers.