lit. idly poke a stick in the mud and it grows into a tree to shade you / (fig.) unintentional actions may bring unexpected success / also written 無心插柳柳成蔭|无心插柳柳成荫
lit. you plant a garden and the flowers do not bloom, you poke a stick in the mud and it grows into a tree / fig. things do not always turn out as one would expect / well-laid plans may fail, and success may come where you least expect it