Liana (Climbing Vine) Passiflora caerulea [Blue Passionflower] This is one of the hardiest passion flowers, dying back in colder climates, but hardy to 10 degrees F. (It is suspected that the specimen at Purdue University in West Lafayette, IN (USDA zone 5a), is kept alive in the winter by the heat radiated from the greenhouses and building it is planted near.) Plant is evergreen in tropical environments. Extraordinary flowers and tasty, edible fruits (passion fruit). Prefers loose sandy or gravelly soil that…