The noun and verb פרח (noun: flower, verb: bloom) is used primarily when talking about a seedling. And it is different than ציץ (bud) which indicates the sprouting of the material carrying its fruit and its sproutlings, which is sometimes before the blooming and sometimes after it. And this meaning is borrowed to describe anything which sprouts very slowly. And this is when it says ואם פרוח תפרח הצרעת וכסתה (And if the leprosy break out abroad in the skin, and the leprosy cover)⁷¹¹; it means to say that it sprouts very slowly.

footnotes: ⁷¹¹ Leviticus 13:12.