Some days a journal seems silly, and yet another listing of what you planted might seem trivial. Yet long term records and evolving impressions and processes are exactly what turn into gold for those who come later. So keep your notes. Who knows which gardener will discover or develop something that brightens the gardening world 50 years from now?
Two shining stars in the ranks of those who never stop learning, and likewise keep on recording, are Michael Dirr and Alex Shigo. Treated for most of their adult lives with reverence approaching awe, they might have withdrawn to a well deserved pedestal, but nope, not these two. Horticultural wizards yet approachable, real, gardeners.
We'll leave it to you to look up their work, in case you don't already know it. When you do, and you've picked your jaw back up off the ground over the wonder of it all, come back here. Look then at these notes (below) so you can appreciate how they really might be just the gardener next door.
What's Up 169: Hardening holly and bottom heat