Life Cycle
Here's how the life cycle works, with a crappy picture to help.
When you plant a vine, ...
1) It starts at a certain life (usually 120 for new vines).
2) Life will drop to ~25% of the starting value.
3) Life will rise to ~75% of the starting value. (The time from point 1 to point 3 is ~16-18 hours).
4) Life will drop to zero.
If you water a vine before it reaches point 3, it will start a new life cycle, with the starting life value "locked" at whatever it is when you water it.
If you water a vine after it reaches point 3, it does nothing. That is, once a vine starts dropping from point 3, nothing you do will stop it from reaching 0 life.
Graphical example:
Here, the black line shows what will happen when you plant a vine and do nothing.
If you happen to water it at point A, the life cycle will start anew. In this case, the life value stops following the black line, and starts following the blue line.
If, after that, you happen to water at point B, the life cycle will start again, and start following the red line. And so on, if you keep watering at intervals.
The scales on the picture are not correct. Each "cycle" (black line, blue line, red line) take the same amount of time.
In short, to keep a vine at above zero life for as long as possible, ...
1) Find your "back to 75% point" (should be between 16 and 18 hours).
2) Water the vine at intervals slighly less than the time found in step one.
