Thanks for the responses, folks, I appreciate it. It's a strange patch of ground, as it only floods for a couple of days twice a year and yet dries out in summer and is a tiny frost pocket in winter! The soil is beautiful, like crumbly chocolate cake, and everything other than the hebe is thriving well. I took some dogwood cuttings in early spring, which seem to have rooted OK, so I will try transplanting those into the gap. Thanks again.
