bloom (n.1) Look up bloom at Dictionary.com
"blossom of a plant," c.1200, a northern word, from a Scandinavian source akin to Old Norse blomi "flower, blossom," also collectively "flowers and foliage on trees;" from Proto-Germanic *blomon (cognates: Old Saxon blomo, Middle Dutch bloeme, Dutch bloem, Old High German bluomo, German Blume, Gothic bloma), from PIE *bhle- (cognates: Old Irish blath "blossom, flower," Latin flos "flower," florere "to blossom, flourish"), extended form of *bhel- (2) "to blow, inflate, swell" (see bole). Related to Old English blowan "to flower" (see blow (v.2)).

Transferred sense, of persons, is from c.1300; meaning "state of greatest loveliness" is from early 14c.; that of "blush on the cheeks" is from 1752. Old English had cognate bloma, but only in the figurative sense of "state of greatest beauty;" the main word in Old English for "flower" was blostm (see blossom).
bloom (n.2) Look up bloom at Dictionary.com
"rough mass of wrought iron," from Old English bloma "lump of metal; mass," of unknown origin. Identical in form to bloom (n.1), and sometimes regarded as a secondary sense of it, but evidence of a connection is wanting.
bloom (v.) Look up bloom at Dictionary.com
mid-13c., blomen, from the noun (see bloom (n.1)). Related: Bloomed; blooming.