Many of us who live in the Waikato are well aware of how difficult passionfruit is to grow here. But Phil Thomson of Horsham Downs has been getting grips with the challenges our climate poses for this delicious fruit.
The main issue is the rainfall and humidity. In the Bay of Plenty where it is less humid and they have less rainfall, passionfruit do much better. I have had one growing in my glasshouse for 10 years but as soon as it sends new growth out through the windows they start dying within a few weeks.
The best ‘habitat’ for a healthy vine has:
- free draining soil to prevent root rot – but you’ll need to water during dry times;
- protection from the prevailing south-westerly winds and rain. The north side of house with a vine trellis under eaves fits this need perfectly as long as the eaves are about 600 mm wide and the trellis is free standing, about 300 mm-400 mm from wall of house to allow some airflow around plant;
- control of slugs and snails to protect the green skin on the base of trunk, otherwise it could get ring-barked. You can place slug pellets under upturned pieces of plastic guttering to protect the pellets from rain damage and pets;
- pruning each year to open up the plant to allow good airflow.
- It’s not essential but if you have a property on a north facing slope this will maximise sun getting to the plant while again giving some protection from the south-westerly wind and rain.
If you don’t have a suitable habitat around the house (or can’t get permission from the partner to have your plant there) then the next-best option is to build a rain diversion device high above your trellis to protect it from 90% of the rain, using polycarbonate roofing to maximise light getting through.
My trial one is one metre wide and five metres long and attached to a well-built (but ugly, my wife says!) frame that is over three metres above ground level. Under that I have a trellis made from left-over security fence panels, but it would be better to have a more open weave, again to promote good airflow and ease of pruning. Ideally I would provide a dozen horizontal wires/ropes about 200 mm apart vertically.
I try to prune to keep all tendrils at least 300 mm above the soil to prevent soil being splashed on the leaves from rain drops, as soil can harbour disease. I also have a layer of bark/chippings to further reduce the chance of soil-borne disease.
(PS you may also have to deal with passion vine hopper but I haven’t had a noticeable problem with it yet.)
Good luck! There are no guarantees but I expect you ‘passionate people’ to nominate me for a knighthood if it works for you, as I have been studying the ‘crimes of passionfruit’ causing sudden dieback for 20 years and you will have benefitted from all my observation and toil (not to mention dealing with the jealousy of my wife who talks of my passionfruit like it was my mistress!). I might post a photo of my most successful ‘Precious’ thriving for its third summer now, and of my glasshouse passion (which is now in its 10th year), so keep a watch out.