Good solution to cure fret sprout before it starts?
 

I've been making my own necks for a couple years now (electric guitar builder). I've noticed that as the weather dries out in the winters the frets sprout. This is old news I realize. But question,
Is there a good way to solve this problem?

Yes....
 

Maintaining the proper humidity level where you keep your instruments is key. In the winter I run a humidifier at approx. 47%. I've never had a problem with "fret sprout".

In theory that's the best answer (especially for a Luthier to have in his back pocket)! But what about for a small builder who knows that most people won't do that? This is something I hear about every winter at least a few times for guitars I built in the summer and boy is it a pain trying to explain this to the customer.

There really is no good solution. It is what it is, especially for those who have to play in a wide range of climate conditions. I believe the best thing to do is when it happens, have a luthier dress the fret ends right then before the humidity rises and the wood swells back. If the wood swells beyond the fret ends, it isn't noticable anyway.

Or, anticipating such, the fret ends can be cut and dressed short to begin with, but this risks them being uneven, so I'd rather have the dressing later.

Fret Sprout?
 

Spouting wings? lol

No, the Frets do NOT ever Sprout. It is the Fingerboard that shrinks around it.