I would suggest some slight changes to Diana's comments to chris on
hardiness of Louisianans.
I agree that "some of the LA's are hardy in zone 4" but not with the
statement that "nelsoni not and probably not brevicaulis either"
nelsoni, in two colour varieties, has been grown by Bruce Richardson
near Hamilton, which I assume is Zone 4 and brevicaulis grows wild in
Southern Ontario also near Detroit which, again I assume is in zone 4.
At the moment, I have something like Dorothy K. Williamson which has
overwintered, flowered and set seed in a shaded spot which was
relatively dry. This plant came from a local stock but I cannot discover
the source (it was obtained in our local plant sale). I understand that
Sandy Ives and Maureen Mark also have had this survive in their garden
in Ottawa for some years. This is in Zone 4B with temperatures down to
minus 35-37C most years, although last year was milder.
I have some of the nelsoni and definite plant of Dorothy K. Williamson
which are just about to be tested in a minus 35C winter (although
projections from El Nino suggest this will be a very mild winter in
Having lived in Ottawa for 20 years now, I remember the North of England
as a balmy tropical paradise where almost anything would grow!