If you’re looking for a plant to spice up the fall garden, try the late, great Plumbagos (Ceratostigma). By “late, great” I don’t mean RIP, but rather blooming its head off when little else still is. The electric blue flowers are stunning and unusual. You could say that it will “Rock your Equinox!” (Autumn, that is).
Cerotostigma plumbaginoides, is a rhizomatous ground cover that has formed a thick, cheery colony in a drier part of my garden, reaching 12-18″ tall. The patch is now about 10′ x 3′ after about a decade in the ground, skirting woody shrubs, taller perennials and bordering my driveway. I’ve divided the plant many times, digging out chunks to grow throughout my garden. I sheer the lifeless, deciduous stems back in late winter and the foliage returns thick and fresh by early summer.
Ceratostigma willmottianum (Chinese Plumbago) is shown at right flanked by silvery foliaged Halimium and glowing yellow Berberis thunbergii ‘Aurea’ . Chinese Plumbago is a taller, wispy but woody plant with very similar flowers, but an upright countenance of 3-4′ tall. Its lower branches skirt the ground so I’ve had success propagating it by layering the branches along the soil and waiting for it to root. Unlike the ground covering species, this plumbago should not be pruned back when dormant. Wait until leaf break to address errant stems or dead branches since live wood is very difficult to distinguish from dead.
Easy to grow in part to full sun and well draining soil in zones 6-9, the stems and leaves of Ceratostigma color up reddish purple as the weather chills, which happens to also be flowering time. Those tints will compliment the deep red color of the spiky tubes that hold the blue flowers and look like little bristly pom-poms when the blooms are done.
Both these plumbagos (also referred to as leadworts) are deciduous perennials that are showy late into autumn and slow to liven up in spring. In fact, they leaf out so late that its easy to confuse them for dead. Their bare, slender and seemingly lifeless twigs will give you pause because almost all other perennials will be up and growing.
However, the patient gardener who lets them be, is treated to the punch of blue that starts in the end of August and coordinates fabulously with other late flowers like ‘Lemon Queen’ Helianthus (sunflower) and ‘Crown of Rays’ Solidago (goldenrod). Good Plumbago companions can have yellow, silvery-blue, variegated and most certainly–purple-red foliage. Its not easy to find, but fall is the time to look for these choice perennials at your local nursery. Happy hunting!