I have noticed that liana vines spawn from dirt blocks in natural caves and even player made caves given it has a light source.
I have tried to create a "curtain" of those above ground level, but they do not seem to grow.
What are the requirements for vines to start growing and what affects the speed of growth?
Best Answer
I'm assuming you mean the vines, as you speak of dirt blocks, and the vines grow from those. They do look like liane.
The dirt block needs to have grass on it. And grass spreads from other grassy dirt blocks. Or, you can use grass seeds, or the Staff of Regrowth.
The only requirement I can find is just a grassy dirt block. Sunlight, underground/aboveground. It all doesn't matter.