The basics are the 5 | 7 | 5 syllables per line, and it doesn't have to rhyme. What I had either forgotten or not known is that it is supposed to be seasonal, even if not obviously seasonal. And it's supposed to have a twist of some kind. So there are two halves, with some change from one to the other that provides a new perspective. Of course she had to do it, because of the season thing, but I still couldn't convince her, so she's doing a boring poster with a sun and the tilt of the earth across the different seasons.
So I decided to write a haiku for each season. Since they don't generally have titles (which would be kind of cheating on the 17 syllables thing, I grabbed some great Creative Commons licensed pics from Flickr to accompany each. Sure, each pic is worth 1000 words, but no syllables, so here they are with my four haiku:
Frigid, wind-whipped, dark,
Sullen stillness, empty streets.
Introvert's blanket.
Golden flowers bloom.
Wildlife fills the savannah.
Dandelions roar.
She reclines in sand,
Ocean waves in the distance.
Aye, mocking mirage.
Final drops, warmth drained,
He leans into coming cold.