Passiflora edulis var. flavicarpa
Although not a distinct species from the purple passion fruit, the lilikoi is a slightly larger fruit, with bright yellow skin and tarter pulp. Most other characteristics of the vine and fruit are similar to the purple passion fruit.
The lilikoi, while botanically the same species as the purple passion fruit has differing climatic requirements. It is a vigorous vine, often growing over 20ft in a single year.
The lilikoi is not nearly as hardy as the purple passion fruit, and is very susceptible to frosts. It will not usually survive temperatures much below 40F.
Flowering occurs from April-November but may occasionally continue year-round if conditions are right. Individual flowers bloom for just 12-24 hours before closing. Unlike the purple form, flowers will not self-pollinate. Either hand pollination or bee pollination yield successful crops. Fruits usually ripen from flowering in 80 days. Pruning is a must to keep the vine healthy. Prune off less vigorous growth and occasionally prune back vigorous growth to promote flowering. The long tendrils need lots of support for climbing. When established, and without care, the lilikoi can easily overtake other garden plants, shading them from sun. The vines love full sun except in climates where the temperature frequently surpasses 100F, vines should be given shade. Water frequently and provide good drainage. Plants are short-lived, usually maintaining good productivity for 4-6 years. Harvest fruits when fruit falls from plant. Fruits are best eaten when wrinkles appear on their surface.
Almost always grown from seeds, but can be propagated by cuttings. Bottom heating the seeds at 70-80F can result in germination at 1-2 weeks, at lower temperatures seeds can take up to 10 weeks and longer to germinate.
It is recommended to pretreat Passiflora seeds before planting. They contain a hard seed coat and are very slow to sprout. There are various pretreatment methods, but the simplest is to soak the seeds for 24-48 hours in warm to the touch water, just prior to planting. Optionally, seeds can be lightly scarified with sand paper to provide some permeation on the seed coat.
Once pretreated, plant seeds 1/2-1" deep in moist, sterile soil. Keep soil temperature consistent at 70-85F, with some day/variation in this range. Cool soils will significantly delay seed germination time if not inhibit germination altogether. Standard room temperature can be too cool for proper germination.
Estimated germination time under optimal conditions: 6 weeks to 6 months.
Pulp is often eaten fresh, seeds are edible. Used as a flavoring in drinks, desserts, sauces, and many other foods. Seeds can be extracted from pulp by putting pulp in a blender on low speed. Run mixture through a strainer to retain pulp and juice. The yellow form (lilikoi) tends to be used more for preceding and less for fresh eating as some people find the pulp too tart or acidic to be eaten fresh, although this varies greatly from vine to vine.
The lilikoi is of an unknown origin. Several theories propose a variety of origins for the vine. It may be a chance cross between P. edulis and P. ligularis, or it may have arose from a chance mutation in wild populations in either Brazil or Australia. In recent years, the lilikoi (its Hawaiian name) is well established throughout Pacific Islands and parts of Central and South America. Despite being an important commercial crop, both types of passion fruits have become major pest species in many tropical regions, particularly Hawaii and other Pacific Islands.