I spent a good part of the day on Good Friday getting
this bed ready for
the predicted 23° night. Had I not built this bed last fall with
exactly this possibility in mind, then saving it would have been
impossible. After the hoops were in place, I bent large cardboard boxes
over their apex, then covered with old bedsheets, and then a covering of
plastic sheeting from Wal-Mart. But before I covered, I strung an
additional 10 ft. section of PVC pipe from the apex of 3 hoops with
wire. Then attached 3 clip-on lights with 70 watt bulbs in them and
covered and heated all those nights in a row that it was below 32°.
Guess it paid off as there are now 9 cultivars and about 15 stalks in
full bloom. Many other stalks are showing color and there are still
several to bloom. Pollen daubing never gets old.
Zone 6b or maybe it's not any more.