What does Judges 16:22 mean?

This statement is ominous for the Philistine enemies who captured Samson while he was weak. It's a hopeful sign for Samson and his people. His supernatural strength was taken from him when he foolishly told his lover about his special calling before God, symbolized by his uncut hair (Judges 16:15–20). Blind and captured, a disgraced Samson is now enslaved and forced to do the work of a lowly servant. That humiliation seems to lead Samson to true repentance, renewed faith, and dependence on the Lord. Parallel to that, his hair grows back as it naturally would.

The Philistines seem blissfully unaware of the implications of Samson's regrowing hair. For their part, they probably assumed that Samson's strength was part of a magical pact with his deity, so once the pact was broken, it was broken forever. Otherwise, they might have continued to shave his head to keep him weak. Of course, the hair itself was never the real reason Samson was so powerful; the hair was symbolic of his God-ordained role. Samson lost his strength because he valued his lusts more than His Lord.

Samson's utter humiliation seems to cause at least some changes in his attitude. Scripture never says how long his hair needed to be to "trigger" God's power, or that such a thing would have happened, at all. It merely notes that it began to grow, and the rest of the passage implies that Samson's submissive faith was growing, as well. Before Samson's story is over, the Philistines will learn they cannot rest easy while God's man is still alive and within reach (Judges 13:5; 14:4).