Chinese native Ceratostigma willmonttianum, below with the blue flowers, was new to me when I started working in my current garden last year. I was already a fan of its smaller relative, C. plumbaginoides, so when I discovered the same great autumn foliage color and glowing blue blooms in a larger plant with a more substantial, shrubbier form, I was smitten.
Ceratostigma willmonttianum leafs out in spring and patiently sits, looking rather nondescript, until autumn. Just as everything else starts to poetically senesce, its leaves turn a vibrant red in bits and blue flowers appear that glow in the increasingly earlier twilights. It hangs on in this wonderful combination of red, blue, and green for weeks, extending the floral interest into the very gateway of winter.
I especially like it combined with the sedum, vitus, phlomis, and melianthus in my garden at work, above. The blues and pinky purples are an unusual take on an autumn color palette and a nice change from the usual yellows and oranges.