In this passage, the punctuation in all editions has a semicolon after the first because-of phrase; this is clearly an error. Both because-of phrases explain why the roots may take strength—namely, because of the inherent goodness of the roots and because of the grafting in of other branches. The semicolon should be removed; in fact, there should probably be no punctuation at all between the two instances of because-of, not even a comma, so that the reader will readily associate the two because-of prepositional phrases.
Summary: Remove the semicolon between the two because-of phrases in Jacob 5:59; these prepositional conjuncts give two reasons why the Lord of the vineyard expects the roots to take strength.