Passion Flower
(Passiflora incarnata L.)

botanical information

Passiflora incarnata L. is a native perennial found in sandy thickets, along roadsides, fields, and fence rows throughout southeastern United States, from Florida to Virginia, west to Ohio, Missouri, and Texas.  As a member of the Passifloraceae family, passionflower is considered one of the most beautiful of all flowers.  Radford et al. indicate that the species can be found growing wild in most of the counties of North Carolina.  A deciduous vine, passionflower climbs using its spring-like tendrils and can grow more than fifteen feet in one year, reaching a mature height of twenty to thirty feet.  The tri-lobed leaves are deep green in color and grow four to six inches.  In Gray's Manual of Botany, M. L. Fernald describes the showy fragrant flower as white, with a triple lavender and flesh-colored crown that blooms in the summer, spreading two to three inches in diameter.  The bloom is followed by an edible two-inch oval, green to yellow berry, commonly known as maypop.  P. incarnata is one of the hardiest species of the genus and is loved by all who have experienced the tranquilizing beauty of its inflorescence.

medicinal uses

According to the Naturopathic Handbook of Herbal Formulas, “As a sedative, passionflower is the preferred herb for treating insomnia and (it) leaves no hangover.  As an antispasmodic, it is helpful in Parkinson’s disease, asthma, seizures, and hysteria.  It relieves nerve pain in conditions like neuralgia and shingles.”  Steven Foster states that American Indians used passionflower root as a poultice for boils, cuts, earaches, and inflammation.

selecting a planting site

A perennial hardy to Zone 6, passionflower prefers a well-drained or sandy soil in full or partial sun.  It can grow in relatively poor, sandy, acidic soils but Tim Blakley, Medicinal Herbs in the Garden, Field, & Marketplace, reports that it does best with a slow release fertilizer, like cottonseed meal, at time of planting.  Since it is a trailing perennial, pick a location where a permanent trellis can be constructed.  This plant produces for several years, so construct a trellis that will last that long.  If the growing area is typically dry, irrigation will need to be provided.  

planting

In the eastern counties and the piedmont of North Carolina, passionflower will overwinter.  In the western and northwestern counties, it is considered a tender perennial – it may or may not overwinter.  Blakley recommends applying a heavy layer of mulch in the colder climates.

 Passionflower can be grown from seed, cuttings, or divisions.  With seed cost quite high for passionflower, it is more cost effective to start seed indoors instead of direct seeding outside.  Johnny’s Selected Seed Co., Winslow, Maine, recommends the following guidelines for starting seeds.  “Germination for passionflower can be slow and erratic.  Sow seeds in flats at a depth of three-eighths to one-half inch deep.  Keep the seeds moist, and maintain a temperature of 85 to 90⁰F.  Seedlings benefit from applying bottom heat to the flats.  Nighttime temperatures should not go any lower than 70⁰F.  Germination usually begins in thirty days and could take several months.  When the true leaves appear, transplant seedlings into larger cell trays.”  

 In late spring, when seedlings are three to four inches tall, transplant outside in well-prepared beds, spacing plants twelve to eighteen inches apart, and rows thirty to thirty-six inches apart.  Have the permanent trellises in place at time of planting, as passionflower will spread quickly through its runners, once established.  It is very important to keep the beds and rows weeded.  A layer of mulch would be very beneficial.

 Once plants are established, cuttings can be made in late summer or early fall.  This is the preferred method by Blakley.  He provides bottom heat to the flats and mists the cuttings regularly.  Rooted cuttings are ready in three to six weeks.  With divisions, Blakley’s advice is to make sure a portion of the main tuber is attached and to plant the divisions immediately.  Transplant cuttings and divisions at the recommended spacing, and keep moist until plants are established. 

insects and diseases

The Index of Plant Diseases in the United States lists the following diseases for P. incarnata: leaf spots, Cercospora biformis, C. fuscovirens, C. regalis, C. truncatella, and Gloeosporium fructigenum; root knot nematodes, Meloidogyne sp.; root rot, Phymatotrichum omnivorum; and southern blight, Sclerotium rolfsii. 

harvesting, cleaning, and drying

Depending upon location and time of planting, passionflower may not flower the first year.  Harvest begins when the plant is in flower, although some buyers have specific harvest requirements that may include waiting until some fruit forms.  It is the aerial part that is cut (leaves, stems, flowers); and harvest occurs once each season.  When harvesting passionflower, keep the freshly cut herb in the shade until harvesting is complete or take immediately to the drying area.  Do not allow the plant material to heat up. 

Blakley reports that passionflower is approximately eighty percent water.  A warm location with adequate airflow is needed for drying.  If a drying unit is not available, a large dehydrator, converted greenhouse, or converted rooms in a barn are areas that can be used for drying.  Dry at a 95-100⁰F, turning the herb often to allow for aeration and to prevent mold from developing.  Good airflow is essential.  For a quality product, full color of the herb must be retained after drying. In a more humid climate, the temperature may need to be increased.  Once the herb is thoroughly dried, package the dried herb in woven poly bags that are light proof or in corrugated boxes, and store in a cool, dry, dark location. 

markets  

Passionflower is sold fresh and dried.  Both wild harvested and cultivated material is sold for the medicinal trade.  From a report by the Ministry of Agriculture, Food, & Fisheries in British Columbia, “Prices are based on selling entire production to a small to mid-size manufacturer.  A more difficult market is selling directly to retail customers, small craft companies, or herbalists.  A higher price could be realized in the smaller market but will increase the time and expense required for marketing and packaging.  Demand for a certified organic product has increased.”   

Felter, Harvey Wickes, and John Uri Lloyd. 1898. King's American Dispensatory. Henriette Kress. Click here for Web site. 

Fernald, M. L. 1970. Gray’s Manual of Botany. D. Van Nostrand Company, New York, NY. 1632 pp. 

Foster, Steven, and James A. Duke. 1990. A Field Guide to Medicinal Plants Eastern and Central North America.  Houghton Mifflin Company, Boston Mass. 366 pp. 

Greenfield, Jackie, and Jeanine M. Davis. 2004. Medicinal herb production guides. North Carolina State University, Raleigh, NC. 

Herbal Research Publications, Inc. 1995. Naturopathic Handbook of Herbal Formulas: a Practical and Concise Herb User’s Guide. Herbal Research Publications, Inc. Ayer, Mass. 217 pp. 

Jensen, Beth. 2004. Johnny’s Selected Seeds. Winslow, Maine. Personal communication.

 Ministry of Agriculture, Food, & Fisheries. 2002. Certified organic versus non-organic budgets for passionflower herb. 5 pp.  Click here for Web site.

Radford, Albert E., Harry E. Ahles, and C. Ritchie Bell. 1968. Manual of the Vascular Flora of the Carolinas. University of North Carolina Press, Chapel Hill, NC. 1183 pp.

 Sturdivant, Lee, and Tim Blakley. 1999. Medicinal Herbs in the Garden, Field, and Marketplace. San Juan Naturals. Friday Harbor, Washington. 323 pp. 

US Department of Agriculture, Crops Research Division Agricultural Research Service. 1960. Index of Plant Diseases in the United States, Agriculture Handbook No. 165. Washington, DC. 531pp.

The North Carolina Arboretum is grateful to Jackie Greenfield and Jeanine M. Davis for their contributions to this publication, including excerpts from their publication “Medicinal Herb Production Guides”. The Arboretum also wishes to thank Richard Rice for his artistic renditions of the herbs. The Superb Herbs Web site and the documents provided were made possible by a grant from the NC Department of Agriculture and Consumer Services, found on the Web at www.ncagr.com.