Ken, if the stems are at least 5 inches, are of pencil thickness and taken directly off the caudex of your Green Giant, then there’s a good chance they will root for you. Place the cut stems in a dry warm place for a couple of days to allow the cut part to callus over, then plant in your preferred succulent potting mix with or without rooting hormone applied to cut.
Note: I have answered Ken's question with some trepidation…I wouldn’t want my advice to be misconstrued as applying to any/every situation with adeniums.
