The first real rain of October is my favorite site visit.
All summer, a garden can hide its drainage sins — the low spot by the patio, the downspout that daylighted nowhere, the bed that was always just a little too wet. Then the skies open, and the water draws you a map of everything you need to fix.
I walk sites in the rain on purpose. You learn more in twenty minutes of a downpour than in a season of dry-weather guessing. So here's my October advice: next time it pours, grab a coffee and just watch your garden. The water will tell you exactly what it wants.