Hmm so concrete pillars seem to be the way to go. They look about three feet high? How deep into the ground do they need to go?
Thank you for your help!
The dragonfruit stems hang down ~3 feet so you should set post tops about 5-6 feet above ground. In sandy soil set posts about 2 feet deep, in clay maybe shallower, so total about 8 feet.
Line post forms with plastic sheeting and cure covered for 1-2 weeks. Mix concrete dry as possible to gain strength, sloppy concrete is weaker. Keeping concrete wet and moist after casting promotes concrete strength.
You could cast posts in a trench dug in soil and lined with plastic, no wooden form needed. Use rebar in concrete.