Purple passion plant is an herbaceous perennial vine that boasts exotic purple flowers from June through September. Hardy only in USDA Zones 10-12, Passiflora incarnata is enjoyed mostly as a houseplant and makes an excellent hanging basket specimen. These heat-tolerant plants grow best when temperatures are between 65 and 75 degrees Fahrenheit during the day and don't drop below 55 degrees at night. Purple passion is relatively short-lived, with lifespan of about five to seven years.
Test your purple passion plant's soil for pH level. Very well-draining, fertile sandy loam soils with pH ranging from 6.5-7.5 are best. Adjust pH as necessary.
Situate your passion plant in very bright light, but out of direct afternoon sun. A spot about three to five feet from a southeastern or southwestern window is ideal. The more light it receives, the more flowers it will produce.
Set the plant outside as often as possible when the weather is warm enough. A bright spot in sun or filtered light is perfect, as long as it's protected from hot afternoon sun.
Water your purple passion plant just enough to keep the soil evenly moist, but don't allow it to stand in water. Let the soil surface dry out slightly in between waterings. Indoor plants may need to be watered once a week April through September, and somewhat less during the winter.
Feed half-strength blooming houseplant fertilizer once monthly during the growing season.
Pinch 1-2 inches from stem tips any time the plant is actively growing to encourage branching, which will produce a fuller plant.
Prune vigorous stems back by about one-third in early spring. Vining stems can grow 8 to 15 feet long, but flowers of overgrown plants my decrease in number as well in brilliance of color. Remove any dead or damaged stems.