So I came up with an easy to implement idea (I believe so) after spent almost an half hour watering my crops.
A watering can .
It could be made out of copper, bronze or iron.
How it works?
When used, it sprinkles water from inventory all around the character, watering all plants, crops and trees inside 1, 2 or 3 tile radius (based on material; 1 for copper, 2 for bronze, 3 for iron; MAYBE 4 for steel, but I think it's overpowered).
Simple as that. :)