Spent two summers watching my container flowers produce maybe three sad blooms each while my neighbor's porch looked like a botanical garden. Turns out I was just guessing at fertilizer amounts and burning roots half the time. Switched to spikes and slow-release feeders — now even my notoriously lazy petunias won't stop flowering. If you kill plants by loving them too hard with liquid fertilizer, this lineup took me three seasons to dial in so you don't have to.