I have a thing for South African plants and this would include Galtonia. I little known summer flowering Hyacinth relative. The bulbs that produced these flowers were originally from Brent and Becky's bulbs. They were planted in Tennessee and found their way north to Michigan. They are planted along a South wall so are in a protected position but are listed as hardy in my zone 6 garden. They are rated to zone 5 on Brent and Becky's website.
Here is a link that might be useful: flower farm and Gardens Blog