If you’d like to be both thrilled and confused by a flowering plant, plumbago, or leadwort, is the species for you. These plants – actually two different genera that are easily mixed up – have masses of lovely blue blossoms that carpet whatever area the plant is growing in. They are hardy and generally easy to care for. The real issue lies in the name and differentiating between the two genera.
The plumbago that’s also known as leadwort or hardy plumbago is Ceratostigma plumbaginoides, a native of China. Another plumbago is Plumbago spp., at least one of whose varieties is known as cape leadwort or cape plumbago (Plumbago auriculata), which is native to South Africa.
Because the two genera have similar common names, and one of them has “plumbago” in its scientific name, you’ll find a mix of descriptions. Some will say P. auriculata is leadwort, others will say C. plumbaginoides is leadwort, and others will say all the plumbago species are varieties of Ceratostigma (which they’re not; both are part of the Plumbaginaceae family, but Ceratostigma and Plumbago are two different genera, meaning they diverge after the taxonomic level of “Family”).
All that being said, if you want “plumbago” or “leadwort,” you’ll need to have the scientific name to find the correct plant.
1. C. plumbaginoides
Rich blue flowers blossom all over this type of plumbago. The blossoms have five petals that curl up a bit at their ends. This grows well in USDA plant hardiness zones 5-9. It loves full sun but will tolerate partial sun; in hotter weather, afternoon partial shade is appreciated. Soil needs to be well-draining. This plant can grow to about 1 foot high and 1 1/2 feet wide via rhizome. Green leaves turn red and purple in fall, and this is an excellent groundcover to plant in areas that are in between other trees and plants. Colder zones require mulching around the roots.
2. P. auriculata (also P. capensis)
Lighter blue flowers that do not have those curly petal edges distinguish cape plumbago. This is a warm-climate plant, growing in zones 8-11 (if you live in Southern California, especially San Diego County, you’ll see this shrub almost everywhere, lining slopes and roadsides). This is a huge shrub that can grow as tall as 10 feet and just as wide. Give it full sun if possible; partial sun is fine. The blossoms have a slight trumpet shape toward their centers and bloom most of the year. The plant is deer-resistant and tolerates acid, neutral, and alkaline soils. This is an excellent border and wall or slope plant.
3. C. willmottanium
Also known as Chinese plumbago, this relatively short plant – it grows to as much as 4 feet tall and wide – grows in zones 6-9. Like other plumbagos of both genera, this one likes full sun but will take partial sun, and it needs well-draining soil. The blue flower have petals with fairly straight ends, creating an almost gently triangular shape, with rounded corners.
4. P. indica (also P. coccinea and P. rosea)
Also called scarlet plumbago, this one’s a stunner. Scarlet and deep red blossoms pepper this plumbago plant, which actually prefers part shade. It grows in zones 8-11 and does well along the Gulf Coast regions and Florida. This plant is poisonous, so keep kids and pets away from it. It can grow up to 3 feet wide and 2 feet high.
5. P. europaea
This plumbago variety has flowers that are pale to medium blue. Petal shapes can vary from wide to rather narrow. This variety is native to the Mediterranean and Middle East but can grow as far north as England. The flowers have a more pronounced tubular shape, and the plant needs sandy, well-draining soil with sun.
6. P. pulchella
Stalks with star-shaped, tubular blossoms distinguish this variety that’s native to central Mexico. Also called iguana’s tail or cola de iguana, these tiny flowers grow in an alternating pattern up a thin stalk. Sepals, seed pods, and stems have tiny spines. The flowers are medium blue with a noticeable line running up each petal from base to end.
7. C. griffithii
Also called Burmese plumbago, Griffith’s blue leadwort and Griffith’s plumbago, this variety is fairly easy to grow in warmer climates. Smallish blue flowers that look a bit ruffly grow along and at the end of stalks; the plant can grow to about 3 feet high within five years. The leaves remain green for most of the year except in fall, when they can turn red. The plant blooms from mid-summer to late fall, and it need full or partial sun.
8. C. minus
This is an interesting plant for fairly hot environments (hardy down to zone 7). Small clusters of blue flowers grow on stalks that rise up out of foliage that doesn’t grow that tall. The petals on the flowers have notched ends, giving them a sort of heart shape. This is a drought-tolerant plant that doesn’t need a lot of water, and it grows to about 2 feet tall. Hummingbirds seem to like it. The plant can tolerate full sun to partial shade.