expression, godan verb (-su)
grow a beard
Standard expression for intentionally growing facial hair; 生やす is a transitive verb meaning to grow something on the body.
彼は夏休みにひげを生やした。
He grew a beard over summer vacation.
ひげを生やすと印象が変わる。
Growing a beard changes your impression.
Standard kanji-kana mixed spelling.
Rare kanji form using 鬚; ひげを生やす is the usual spelling.
Intransitive counterpart: 'a beard grows' (naturally), while ひげを生やす is the deliberate act of growing a beard.
Compound of ひげ (beard) + を (object marker) + 生やす (to grow something on the body). The verb 生やす is a transitive form related to 生える (to grow, intransitive).