The wreath itself has a history that predates Christianity. There are many instances of the using of a wreath long before Christianity adopted it as a symbol of the crucifixion of Christ (the Holly representing the thorns and the red berries the blood of Christ).
Persia is believed to have been the origin of the wreath where members of the royal family wore jewelled headbands. The Laurel wreath was used as a garland for the winners of events in the Olympic games as early as 776 BC. Early Eastern European people used to light candles attached to a wreath in hope of an early spring and warmer weather.
The transition from head adornment to wall or door decoration is not clear. Most sources assume that returning soldiers or athletes hung their headbands on the wall on return to home.
Ancient Druids believed there were magical properties in Holly, possibly as it is an evergreen and therefore does not ‘die’ in the winter. Thus they probably considered this to be a symbol of eternal life. The circular shape of the wreath also represents eternal life with no beginning or end, again the ancient symbolism was adapted by Christianity.