"This Plant Thrives in Drier Environments"
Honestly I love the fact that this kind of sign exists. I've seen them in a few places (including my apartment building) and they're one of my favorite things. While simple, I feel like they represent something important about society.
Most people don't know a ton about plants, but people do know that taking care of plants requires watering them. While the actual amount of water a plant needs varies by species, people don't know that. What they do know is that plants need water.
What this sign represents is that enough people wanted to help take care of the plant that they were overwatering the plants. Literally drowning them with care. They don't know that what they're doing is too much for the plant, they're just trying to help. And enough people are trying to help that signs are needed to say "hey, trust us this plant's okay, we've got it!"
And I just think that's kinda neat.