Is "Here we come a-wassailing" supposed to be sung at Christmas?

Question

Here we come a-wassailing is a traditional Christmas tune but it has almost no mention of the traditional Christmas subjects. The only one I can see in the entire version printed in Wikipedia is in a verse I've never heard before myself:

Bring us out a table
And spread it with a cloth;
Bring us out a mouldy cheese,
And some of your Christmas loaf.

The first verse, though, which is pretty universally known talks about "leaves so green".

Here we come a-wassailing
Among the leaves so green;
Here we come a-wand'ring
So fair to be seen.

Generally one doesn't think of green leaves and winter time. Yes, the chorus says "God bless you and send you a happy New Year", but different cultures have celebrated the new year at different times.

During the Middle Ages in western Europe, while the Julian calendar was still in use, authorities moved New Year's Day variously, depending upon locale, to one of several other days, among them: 1 March, 25 March, Easter, 1 September, and 25 December.

So, was this actually a "Christmas" song, or was it intended to be sung at some other point in the year. If designed for December, what "green leaves" are we talking about?

Answer 1

The plants that grow green in European wintertime have become entwined in the myth and rituals of the season.

Celebration: Proceedings of the Oxford Symposium on Food and Cookery 2011 ascribes the 'leaves so green' of the song to the bowl's being decorated with Rosemary and other evergreens.

Other evergreens could have included Mistletoe

Mistletoe continued to be associated with fertility and vitality through the Middle Ages, and by the 18th century it had also become incorporated into Christmas celebrations around the world.

Holly and Ivy are often treated as a pair when talking about yuletide evergreens. (mature holly in a woodland can be as spare and lanky tree which lends itself to ivy swarming its trunk. In the winter this can give the striking effect of a fully clothed tree with two sorts of leaves. In fact with three sorts, when ivy gets to the top of its climb it puts out a branches rather than runners and forms a 'bush' with non-lobed leaves. The bush flowers and sets berries. This could go some way to accounting for all the colours of berry attributed to holly in the 'Sans Day Carol' as Ivy berries set green and ripen black.)

holly and ivy have been a mainstay of British Advent and Christmas decorations for Church use since at least the fifteenth and sixteenth centuries, when they were mentioned regularly in churchwardens’ accounts They are also the subject of numerous carols, the example still current being a carol which may date to the 1700s

The holly and the ivy, When they are both full grown,
Of all the trees that are in the wood,
The holly bears the crown.
The rising of the sun
And the running of the deer,
The playing of the merry organ,
Sweet singing in the choir.