Combination boxes are handy, but honestly, I've had mine freeze shut during a bad ice storm—talk about ironic. Maybe consider a trusted neighbor instead? Saved me from freezing on my porch more than once...
Combination boxes are great until they're not...been there with the ice storm fiasco myself. If neighbors aren't an option, try a weatherproof lockbox tucked under an overhang or porch step—saved me from awkward porch pacing more than once.
Totally agree about the lockbox—saved me a few times too. But honestly, even those can freeze up in bad weather. I've started keeping a hidden spare key wrapped in waterproof tape inside a planter...works surprisingly well and blends right in.
Good call on the planter trick—pretty clever! But what happens if you rearrange your plants or someone decides to "help" with gardening? I've had well-meaning family members move stuff around without telling me, so I'm a bit wary. Have you ever had issues with that? Personally, I've started stashing a spare key taped inside my shed door...less chance of accidental relocation, and sheds rarely freeze shut.
Yeah, the planter trick backfired on me once when my wife decided to "freshen up" the porch—spent half an hour digging through flower pots like a squirrel. Your shed idea sounds way safer...might have to borrow that one.