We think of passion flowers as something exotic, tropical and certainly not something you can grow in Colorado. Fiddlesticks! There is a garden in Littleton where passion flowers are practically a problem. Sandy Snyder (who worked at Denver Botanic Gardens for 17 years as horticulturist) has perhaps the finest private garden in the metro area. The south side of her house is positively DRAPED with passion flowers (see below): in fact, she weeds them out (they do sucker a bit much, you know). Right now, the whole glorious wall boasts hundreds of these frilly, incredible Faberge gem-like blossoms. I know a garden in West Denver (Jim and Dorothy Borland) that has a similarly rambunctious white flowered passion flower growing just as vigorously. Sandy's plant originally came from the South Denver garden of Tom and Ann Johnson, who passed away decades ago--great gardeners whose plant and memory lives on.
We have not yet managed to grow this outdoors at Denver Botanic Gardens, although we have quite a few passion flowers in the conservatory and containers. But I suspect one day we will.
Isn't it amazing what the great gardeners of our area are doing?