What is probably the earliest version I have (later printed by Pitts and Catnach) from the 18thc 'Court of Apollo' songster, has the first line, 'I'll spread these green branches all over her young' I very much doubt this has any negative reference as the rest of the first stanza is explaining how happy he is at this stage. Here's the full stanza.

I'll spread these green branches all over her young,
So well I do like my love so sweetly she sung,
Was there ever a young man in so happy a state,
As I with my Flora, my Flora so great.

There are all sorts of possibilities as to what the first line means. If it has been corrupted as often happens in both traditions it may mean nothing as it stands. It could well be that the person who supplied the first version to the printers heard it at the pleasure gardens and misheard something like what you have, Vic. All of the versions I have that have that first line have it as I give it above, no variation. It might become clearer when I've had chance to look at the other 2 variants.