I've never ever used a herb just because it's a diuretic.
Giving a diuretic just to get some watery swelling down is a bad idea. That's not addressing the underlying problem -- which will get worse while you're suppressing symptoms. I could just as well be a doc, with 10 minutes per client, were I to go that route.
Instead of giving diuretics for swollen ankles I want to know why those feet are swollen. There's lots of candidates:
Do you have digestive problems -> overloaded liver -> lots of gunk in the blood -> compensating kidneys?
Do you have liver problems -> lots of gunk in the blood -> compensating kidneys?
Are your kidneys keeping in too much water, and if so, why?
Do you have heart problems?
Let's not remove your symptoms, let's instead do something about the cause, and let's help your organ weaknesses. That'll make a lasting impression on the symptom, and you won't have to keep taking these herbs forever more.
The only time it's important to know if a herb is diuretic is when you're giving one to somebody: you have to tell them not to drink that tea in the evening. Or, if they do, they should be prepared to get up to pee in the middle of the night. Or to get a warm feeling, for an all too short while ...
But to use diuretics just because they're diuretic? I don't do that.