How do you water other's flowers?

Yes I wanted to ask about that too. Sometimes I get the message "You watered the plant with some dew", and the flower gains half a drop. And on the other hand, there are times when I get the message "You watered the plant with some dew" but nothing happens, or I don't get the message at all, despite the fact that I haven't clicked this particular flower on that day. It would be nice if we could water other people's plants like our own ones

I think the only way so far is to know your friend's password and to play minigames for her/him. The Terms do allow 'garden sitting' for a short period of time.

"6. However, it is tolerated, over a short time to keep an account from another player."

The English version is a bit vague, but German one is clear enough.
However, I hope there will be some way to water friends' flowers without actually logging in to their accounts. Or maybe there is such a possibility already, and we simply don't know?
Waiting for the final word from the Mods

Flower game is not a critical game. Normally never give your password to other hands. Perhaps I thought I was give it to a friend, than I see, it is a *Quatschmacher*, so I can get a problem.

If it makes sense, the game can create sitting. I think, to watering a friends garden the team will create a fine, funny appropriate solution. If it shell by, it will come later. For now other themes have the priority.