All the half-baked ideas that pop into your mind. Have an easy way to capture them.
I think it's a thing from Ahrens and/or Zettelkasten.
These are all the ideas that pop into your mind. Always have a notebook or a note taking app with you to capture these. They can be very short—just one word for instance. The goal is just to remember them for a very short amount of time, until you can sit down and write a proper note
If I'm at my computer, I capture with org-capture. If I'm somewhere else, orgzly new note is where my fleeting notes go. So they first go into my Inner garden. Which is really more of a personal to-do system, not so much a garden.
When I tidy my inner garden up I move the relevant fleeting notes (i.e. the ones I think might be worth putting public at some point) either in to my journal, or in to To FILE in my public garden. They clog up my inner garden otherwise with random quotes and shit, which get in the way of the things I actually need to be doing with my life.