Tips for Serbian Bellflower propagation please. – Reddit Post

Around where I live, loads of front gardens have Serbian Bellflowers growing out of the tiniest cracks in front walls. There would appear to be many of varieties, and most them are absolutely gorgeous. Our wall has pretty nondescript weeds in most of the cracks that support life. Does anyone have tips on how to establish Bellflowers – I’ve tried taking small plants and, basically just pushing the roots into cracks, but no success so far. It’s a mystery to me how these plants get there in the first place. Any useful suggestions would be very welcome.