Pansy, Domestic plants need some kind of cultivation and care such as watering in order to grow. Fools, on the other hand, need no special cultivation or training. The ability to act foolishly is a natural talent they possess. In truth, we have all acted like fools at some time or another in our lives. You might use this proverb when referring to someone who often acts foolishly. However, the word "fool" is a bit old fashioned. At one time it was used for people born with less than normal mental ability, but now it would be considered cruel to speak of them in that manner. There is another other more interesting proverbs about fools. --Fools rush in, where angels fear to tread.--

"Watering" refers to the day to day care needed to make something grow. I think the picture here is obvious. However, fools seem to appear without any day to day care whatsoever.