My thumb is not green, don't even bother to check. I water, weed, fertilize, & tend; and often, in spite of my best effort, the things I plant fail to thrive.
And yet in the natural world, left to their own devices seeds take root in unlikely places. Flowers bloom where they are planted. Seeds germinate and sprout between rocks. Roots are sent deep to draw water and nutrients from hidden sources. Seedlings grow into little plants that hang on tightly to their place in the world. And then they blossom, fulfilling their destiny in spite of the odds.