A retired botanist in Raleigh set me straight on my dying ferns

I stopped at Logan's Garden Shop in Raleigh about three Saturdays ago to grab more fertilizer, convinced my two-year-old Boston ferns just needed feeding. A retired botanist named Walter watched me pick up the same bag twice and finally said, plain as day, 'Son, you don't have a feeding problem, you have a watering problem.' He had me stick a finger two inches down into the pot right there on the counter, and it was bone dry while the top looked dark and damp, which was the whole mistake I'd been making. Has anyone else had a plant person hand them a simple test that fixed something they'd been getting wrong for seasons?