I'd like to try growing a passionfruit vine from seed. My best guess on a good way to do it would be to dry the seed out well first, then soak it for a day or two to help it germinate, then put it under the some soil in a seed tray.
Is there a better technique?
According to Norman Deno in Seed Germination Theory and Practice (2nd Edition), the seeds of passion fruit (Passiflora edulis) germinate best if they are provided a moist, warm (70ºF, 21ºC) period for three months, followed by a cold, moist (40ºF, 4ºC) period for three months, followed finally by a moist, warm (70ºF, 21ºC) period (81% germination in the fifth week following the last temperature change).
In his First Supplement to Seed Germination Theory and Practice, Deno added the following information:
P. edulis had been found to germinate in a 70-40-70 pattern (2nd Ed.). Thelma Norman of Mena, Arizona, now reports some interesting results. Commercial seeds of P. edulis, P. antiquiensis, P. malformis, P. mollissima, and P. vitafolia were inadvertently exposed to temperatures of 125ºF for several days shortly after sowing. All germinated in 6-10 days. Presumably the chemical system blocking germination can be destroyed not only by 70-40 treatments, but also by high temperatures in the 125ºF region. P. cinnabarina and P. coccinea failed to germinate in the above treatment.
I, personally, suspect that, for passion fruit and some other fussy germinators, fresh seed may germinate more easily.
I grew passiflora alata from seed a few years ago. The seeds were dry (purchased from a garden store). My method for fussy seeds like this is to put them in a ziplock bag with some damp sphagnum moss. When they start to germinate they can be potted into small containers. I find that putting them right into soil makes them harder to keep moist and also harder to see what is going on.
