"Lo, How a Rose" is a great idea for the Annunciation.
Be certain to add a verse that mentions the Blessed mother specifically. This is one of those hymns that pre-existed the Reformation, and so there are both Protestant and Catholic versions. It is most unfortunate that Catholic hymn editors of 60 or so years ago went to Protestant books, rather than seeking out the Catholic forms.
Irvin M. Udulutsch had another verse in "Our Parish Prays and Sings," a little paperback hymnal from ca. 1959.
And one more, Catholic Hymnal: A Collection of Standard Catholic Hymns... By John G. Hacker can easily be found in Google Books, and there is a Catholic verse on page 47.
There are a few other translations in other obscure German-American hymnals from the first quarter of the 20th century.
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