From PinataIsland.info, the Viva Piñata wiki
The Watering Can is used to water flowers and vegetables so they do not die. This process must first be done by yourself, but it can be done later by a Sprinkling helper.
When it rains, there is no need to water your plants.
The flowers turn yellowy-brown when they are too dry, but when watered they instantly are restored to their best state. If the plant starts turning blue, you're giving it too much water, which can also kill it.
Plants can be watered -- many need to be watered periodically until they are fully grown.
Some pinatas like to be watered at any time.
Some pinatas like to be watered sometimes.
Some pinatas prefer not to be watered.
Watering a pinata that has started a fight (whether it is a resident or a wild sour) can sometimes stop the fight.
Some characters like to be watered
- Night Watchlings
- Day Watchlings
Some characters prefer not to be watered
Some ruffians will stop in their tracks and begin to spin slowly around if you water them continuously. This could give your resident pinata a chance to get away from the attacking ruffian.
Watering Can Upgrades
- Tin Watering Can (225 coins at Costolot's General Store)
- Gold Watering Can (750 coins at Costolot's General Store)
- Glass Watering Can (1575 coins at Ivor Bargain)
- Everpour 5000 Watering Can (2700 coins at Ivor Bargain)
- One Pour Wonder (4125 coins at Ivor Bargain)
Watering Can Achievement
The 'Watering Can Do' achievement is awarded for fully upgrading the watering can. You don't need to buy all the upgrades, just the One Pour Wonder, although you will miss the Tool Awards for owning them.
The Water Meter shows how much water a plant has. You can use the Water Meter to make sure conditions are ideal for the plant to grow. A balance of half-blue (wet), half-white (dry) is just right.