Campanula poscharskyana (Serbian bellflower) makes a great underplanting for taller perennials or shrubs. Covered with pretty star shaped blooms, this low growing perennial still manages to shine in the shade of other plants.
I have some Campanula poscharskyana ‘Camgood’ (marketed as ‘Blue Waterfall’) planted under a Hydrangea, and I’m partial to the way the blue flowers look as they shine through the Hydrangea branches. They easily fit into the open space under this shrub, looking much prettier than mulch.
These Campanula poscharskyana are planted under a tall Cimicifuga (bugbane). I especially like the blue stars twinkling through the purple tinged foliage of this perennial, which will not flower until much later. The Cimicifuaga is sparse at the base, so this groundcover does an excellent job of preventing weeds from growing, while looking pretty.
I also use Serbian bellflower as an edging plant. This dwarf perennial add a little blue sparkle to the front of the border. The plants have dozens of these attractive five petaled stars.
I’ve read that Campanula poscharskyana spreads quickly, but I haven’t had any problems with it here. It might be that the zone 3 winters slow it down, or maybe ‘Camgood’ (‘Blue Waterfall’) is better behaved than others. In fact, this is one of the few perennials that I lost some of over the winter. To be safe, you might not want to plant it next to delicate plants, or in a rock garden, until you see how it does in your garden.
Doesn’t this Cimicifuga above look bare without some Campanula underneath it? It needs a dwarf groundcover, with pretty flowers at its base.
Campanula poscharskyana is great for underplanting because it handles medium shade well, and it is very low growing. My plants are about 10 cm (4 inches) tall, and the flower stems mostly spread out, rather than up. Serbian bellflower is a great groundcover to offset the leafy growth of taller shrubs or perennials. What plants do you like to use for underplanting?
Update: my ‘Blue Waterfall’ died out after a later winter, but you can read about two other Campanula poscharskyana that survived and flowered well.