Answer: There are many Heather species and the hardiest are native to northern and western Europe. A Mediteranean species is only intermediate in hardiness and the South African species is definitely tender and requires winter protection. It's possible that the white flowering heather you've planted is of the more tender species. You can try protecting it from freezing weather by surrounding it with a tomato cage and piling leaves in around it. You'll need to be careful in packing it up for the winter, though. Since the stems and leaves will remain on the plant, if you pack the protection down too far, you'll end up with a funny looking plant when you remove the mulch in the spring. A better solution might be to find a specific white flowering heather that will perform well without winter protection. Try planting Erica canaliculata 'Springwood White', or E.c.'Stoborough'.
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