photo from here
Paschal Time is over, we are back to "Ordinary Time". So why does the Church choose the colour green for this season?
It is perhaps easy to think that the Church arrived at the choice of the colour green for what we now call, "Ordinary Time" by pure accident but a non-fugitive green dye for vestments before the industrial revolution was problematic, white, brown, russet, yellow, even indigo blue are easier to achieve. In England green cloth was produced by the dyers of Lincoln, a great cloth town in the high Middle Ages, by dyeing it with woad, Isatis tinctoria to give it a strong blue, then overdyeing it yellow with weld, Reseda luteola or dyers' broom, Genista tinctoria.
In the Oriental Rites green, not red, is the colour that signifies the Holy Spirit, it is the preferred option for Pentecost vestments. The Angel in the Rublev Old Testament Trinity that represents the Holy Spirit is clothed in green. It is worth remembering that Pentecost was originally the festival wheat harvest. In most Oriental Churches churches are decked with greenery at Pentecost.
In the old calendar "Ordinary Time" was "time after Pentecost", a better term. The deliberate choice of green vestments symbolised a time of fecundity for the Church, a time when the Paschal Mystery is accomplished, when the Church is living in the time of the Spirit. Lent, Advent and Eastertide are times when the Church re-orientates itself fixing its attention the Mysteries of the Lord; "Ordinary Time" or better "Time after Pentecost" is when the Church looks out to the world, fulfilling its mission.
It is therefore a sign the Kingdom of God, all those references to growing shoots, trees, vines in the Gospels, to its quiet unnoticed growth, it is also the sign of fucundity and and of life.
Bishop's wear Amethysts because the word a- "not" and methustos- "drunk" because they are the successors of the Apostles of whom it was said on the day of Pentecost.
For these are not drunk, as you suppose, seeing it is but the third hour of the day: Acts 2:15