No supports needed.

Important note: Some makers reported that their vase is leaking. The model itself is tight and should not leak. There are several reasons why the vase may still leak. Here I list some of the reasons and how you can remedy them:

Material: 
PLA seems to leak more then other materials. There is a really good youtube video from “Let's Print” that handles this topic:

Wall gernerator:
The default / classic wall genrator might lead to areas without any infill. Use “Arachne” instead. This ensures that a filler wall is printed in addition to the outer walls (see screenshot).

Default / classic wall generator (0.4mm nozzle):

Arachne wall generator (0.4 mm nozzle):

Scarf joints:
A hard step in z-direction after a layer is finished might also lead to a leaky model. Use scarf joints if available. And it looks better :-)