Plants are an Object that can be grown and killed.
When Water comes into contact with a Plant, it begins to grow and continues to until it reaches its maximum length. When it does, the Plant grows flowers and sound can be heard. Every drop of Water increases the Plant length by one, until it reaches its maximum length where it can no longer consume Water.
When Fizzle comes into contact with a Plant, it is killed and becomes dark. Every drop of Fizzle "lowers" the Plant by one, until enough Fizzle has completely destroyed it.
If a Plant has been killed by Fizzle, but part of it remains, Water cannot grow/heal it. Water just hits it like any ordinary Object.