Hidcote and Munstead are said to be the hardiest of the lavenders (zone 3). Calamagrostis Karl Foerster is a beautiful ornamental grass that is hardy and non-invasive.

Thanks Pudge for the reply I will heed your advice.

Hello! I am in Ottawa where we have about 4 FEET of snow on the ground but onions & leeks growing under our basement lights. I agree about the lavender varieties - Hidcote or Munstead. In terms of grass, I grow the very tall Miscanthus sinensis - the plumes bloom late summer and make a really nice accent in the winter garden. Although my patch has grown a bit bigger over the years, it is not invasive.