You could say that this applies to all plants, but the key to a successful passionfruit plant is great soil.
Starting with any old soil is fine, but the key is to change that soil into living soil. Preparing the soil to hold moisture and nutrients while harboring millions of beneficial bacteria and bugs will make the soil alive.
Currently the yard which we own consists of red sandy loam. Over the course of the next three months I plan to dump large quantities of compost and manure around to turn it dark brown and almost black with organic matter. This will create a perfect soil for the fruit trees I plan to grow, especially the passionfruit.
Thoroughly dig the whole garden bed to a depth of 30cm or one shovel depth. This breaks any compacted surface layers and allows for moisture to enter.
In the areas where you intend to plant out passionfruit vines, dig a 30cm deep hole and put that dirt aside. Inside the hole loosen the dirt to a depth of 30cm, then fill the hole back in with the dirt you removed, this should bring the garden back to the original level. By loosening the soil deeper where you intend to plant, water will naturally migrate to that area giving your plants extra water they can access.
Find a source of manure. Sheep, cow, horse, goat, donkey, chook, in fact any manure from a grass eating animal is good (dog and cat manure can spread disease and smells awful). My preference is horse or cow mostly due to its availability, your best bet is to make friends with a local farmer or race horse owner.
* Chook / Chicken manure is very high in nitrogen and needs to be composted with straw for a couple of months so it does not burn your plants.
Spread your manure in a thick layer (150mm /6in) across the garden bed and lightly fork in.
Apply mulch. An easy and cheap mulch is grass hay, this can be obtained from your local produce agency or local farmer for a reasonable price. A round bale covers all of my garden beds (and then some) and it looks great.
Spread the mulch out in a thick layer across the manure to prevent any rouge seeds from germinating, and to keep the moisture in.
Water well, possibly put the sprinkler on for a good hour each week to soak the mulch and the soil below. This will give the bugs a nice humid environment to grow and breed in.
Wait three weeks for the manure and soil to settle and plant out your passionfruit vines.
By following these simple steps, your passionfruit or other crops will have the best start to giving you plentiful amounts of fruit.
Strawberries are another great plant you can plant around the base of your Passionfruit vine while it develops. The grass hay will protect the fruit from being spoiled by touching the ground.