In trying to write a haiku, you have to depend on old ideas in order to be understandable. Using the images of plants that are unfamiliar to the reader make the poem useless, make the reference useless.

If the reader doesn’t know that crêpe myrtles are lush in the summertime but they do know that daffodils come up in the spring, then crepe myrtles aren’t the useful image that a daffodil is. Everyone knows that leaves turn color in the fall. They don’t necessarily know that the colors of the leaves, as they’re bursting in the Spring, give an idea of what those autumn colors will be. If someone doesn’t know that lilies bloom after irises, summer rather than spring, those references may not work.

Obviously, whether those things matter depends on the image that the writer is trying to convey.

I would be curious to see some of the books of words that are published for haiku writers.