Dwarf Plumbago, Leadwort

Family:Plumbaginaceae (family)
Genus: Ceratostigma
Species: plumbaginoides

May seems to be the month that’s reserved for my favorite plants. Dwarf plumbago, Ceratostigma plumbaginoides, has earned a place in my personal Plant Hall of Fame. While it’s just now emerging from its winter’s nap, one of its finest applications is as a cover for fading foliage of spring bulbs. So if you’re feeling frustrated about those yellowing straps of daffodil and tulip leaves, consider putting C. plumbaginoides in your bulb bed. Its show is just beginning while the bulbs give their final bows. The shallow root system of C. plumbaginoides won’t interfere with your bulbs; the cultivation requirements are similar; and as you’re feeding your dwarf plumbago, you’ll be nourishing the bulbs for their repeat performance next spring.

No photographs do this plant justice. The brilliant blue flowers that emerge in late July and last until first frost are absolutely electric without sidestepping into the category of “garish.” They offer a true-blue complement to the other robust colors offered by the late-summer stalwarts of Northwest gardens. The foliage that precedes bloom is deep green; as the flowers emerge, the leaves develop a rich bronze cast that only deepens as the weather cools and the days grow short. This plant is breathtaking under Acer palmatum ‘Crimson Queen’, for the bronze tones of the dwarf plumbago match perfectly the color of the small maple’s leaves as they droop down and mingle with those amazing blue flowers. It’s a real “wow” and unlike some serendipitous magic moments in our gardens, it’s a perfectly dependable one that repeats every year.

As for the basics, C. plumbaginoides is of short stature, about ten inches tall. It spreads slowly, never invasively, and is suitable as a small-scale ground cover. In fact, it is at its most attractive when massed, and much less effective as a single specimen. Its ancestry is Mediterranean, so it appreciates our dry summers. It actually does best in less-than-perfect soil, although good drainage is essential. It requires only moderate water and is not susceptible to pests or diseases. Slugs actually avoid it, if you can fathom that. It dies back completely during the winter, so the only clean-up required is the shearing off of the old, dead stems before the new growth emerges in late spring. This lovely plant is fully hardy in Bellingham, although you might want to cover it with a winter’s mulch if you live in the north county. Officially, it can withstand temperatures as low as ten degrees below zero.

A regimen of regular care will keep it happy, and it will survive some neglect without complaint. Its continuing presence in my own garden attests to that. Grow it in almost full sun where it can show to full effect. Spreading out from under the spotty cover of a small lace-leaf maple is perfect.

Ceratostigma plumbaginoides really doesn’t demand much in return for the spectacular show it provides every summer and fall. It belongs to a very tough family. I’ll have to write more about the other members of the Plumbaginaceae family in a future column—I’ve used up my allotted space for this one. So stay tuned. And speaking of future columns, at the mock clinic in April, one of the new Sprouts—my affectionate if irreverent term for newly trained Master Gardeners—asked how I choose which plants to write about. Lots of factors go into my decision, including mixing the unusual with the familiar, the easy-to-grow plants with more exotic ones, reviving old standards and touting newcomers. I try to hang some text on the season at hand, always remembering which plants work here and which don’t. But it is most definitely a delight to respond to reader requests. So, if there’s a plant you’d like to know more about, or one you’ve found that you’d like to share with others, please let me know. All suggestions are welcome. Just let me know by phone or send me an e-mail at cheryll@cgkwordsmith.com, and I’ll do a write-up on your favorite plant.