The first step to growing passion flower from seed is to break seed dormancy. The seeds have a hard seed coat that requires special treatment to stimulate germination. Passion flower seeds can be collected from ripe passion flower fruits and processed for planting, or they can be purchased from a seed company or nursery. Soil, container size, heat and moisture all play critical roles in successfully growing a passion flower seed.
When collecting passion flower seeds from an existing vine, the fruit should be allowed to ripen on the plant. Once picked, the fruit should be fermented at room temperature for two full weeks. The fermentation process in the fruit prepares the seeds for germination by killing off fungus that can cause rot problems.
After the two-week fermentation process is complete, the fruits can be placed in a sieve and mashed thoroughly. The mashing process breaks up the fruit to release the seeds. Once the seeds are exposed, the fruit is rinsed off with cool or warm water until the seeds are clean and free of pulp.
In order to germinate, the passion flower seed must absorb water. To allow this, the hard seed coat needs to be broken. One of the best tips for planting passion flower seed is to gently break the seed coat by rubbing it between two pieces of fine sand paper. Once the seed coat is broken, the seeds should be soaked for 24 hours in warm water.
The seeds should be removed from the water promptly after the soaking periods is complete and potted in 2-inch (about 5-cm) pots. A good tip to promote drainage when germinating a passion flower seed is to cover the bottom of the pot with a 1-inch (about 2-cm) layer of sand. The rest of the pot should be filled with quality potting soil.
A depth of 1/8 inch (about 5 mm) is ideal for planting a passion flower seed. The soil should be soaked thoroughly after planting the seed, and the pots should be watered whenever the top of the soil starts to feel dry. For best germination, a temperature of 79°F (about 26°C) should be maintained during the germination process. A passion flower seed takes eight to 12 weeks to germinate.
The seedlings can be planted out in spring after the ground thaws. In frost-free climates, a passion flower seedling can be planted out any time of year, but cool winter and early spring weather is ideal. Passion flowers grow best in a spot in full sun or part shade. These vigorous climbers also grow best when given a structure to climb but can be kept house-plant size with regular pruning as well.
The passion flower, or Passiflora, is a genus of climbing vines that includes both tropical and cold-hardy species. Tropical species, such as Passiflora coccinea, can be grown outdoors in frost-free climates or indoors in a greenhouse or sunny room. Cold-hardy Passiflora incarnata, on the other hand, can withstand temperatures as low as -10°F (about -23°C). In areas where winters rarely drop below 10°F (about -12°C), Passiflora caerulea is a suitable choice. In both tropical and temperate gardens, the large passion flowers lend an exotic look.