Ceratostigma plumbaginoides; was Colchicum byzantinum and friends

Jim McKenney jamesamckenney@verizon.net
Thu, 15 Oct 2009 18:53:32 PDT
Jane McGary wrote: "I hope to combine the big colchicums with Ceratostigma plumbaginoides if I can just figure out the trick to propagating the latter. (It ought to be a no-brainer, but nothing I try results in a quantity of viable plants.)"
Jane, for many years I had a nice planting of Ceratostigma plumbaginoides (about three square yards in area) underplanted with the large-flowered tessellated colchicums sold as "The Giant" or "Giant". For me, it was one of those combinations which, while it looked great on paper so-to-speak, was not completely satisfying in the garden. Why? Becasue the blue of the Ceratostigma is a very chilly blue, and the color of the colchicums is equally cold. 
Ceratostigma plumbaginoides ramps like a champ here, and it eventually invaded a clump of Sternbergia lutea. Now that's a combination to love! Those two really sing well together. I'm redoing big sections of the garden right now, and I'm looking around for a place to prominently show off that pairing. 
Because the leadwort emerges so late in our climate, extensive plantings of it don't have much to offer early in the year.  One way to take advantage of that is to underplant the leadwort with early blooming plants which are summer dormant. But to my tastes, an even better way to take advantage of that space early in the year is to underplant thickly with Lycoris. Their foliage will be up and busy from late winter into late spring; by the time the leadwort kicks in, the lycoris will be dying back. 
Lycoris radiata, L. sanguinea. L. sprengeri (in other words, lower growing sorts) and Sternbergia lutea (and if it grows in the garden for you, Rhodophiala bifida) make for a merry show when blooming over a thick mat of leadwort. This is also a great place for any hardy Zephyranthes or  Habranthus. And if your climate allows, this is also a great way to grow Tigridia pavonia. 
Jane, you mentioned problems with propagation of Ceratostigma plumbaginoides. Here I just dig it up, pull apart the wiry tangle, and replant the pieces (which rarely have much in the way of a root system). 
I got my start with Ceratostigma manyt years ago from a commercial source which for one season only offered six-packs of plants (propagated evidently by cuttings and probably under greenhouse conditions because they were sent out early in the year).  
I've tried C. willmottianum here without much success, but for years a thick plant of C. griffithii has done very well in one of my cold frames. However, this species comes into bloom very late (it has not started yet) and would be a dubious choice for me as a garden plant. 
Jim McKenney

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