Each year the Church honors Our Lady of Guadalupe on December 12. This day commemorates the day when St. Juan Diego saw the Virgin Mary and gathered roses during a time of the year when they should not have been in bloom.
December 12 marked the fourth apparition of Our Lady to St. Juan Diego, though it was an apparition that he tried to avoid, as The Month: A Catholic Magazine narrates:
The next day was the 12th of December. Juan Diego started before day dawn for the city, but on coming to the Tepeyac...he began walking round instead of over the hill, thinking he would thus avoid meeting her.
However, "he suddenly saw Mary coming down the hillside towards him and falling upon his face he begged her pardon."
She reassured St. Juan Diego that his uncle would be well and then gave him a most unusual instruction for this time of the year.
Mary ordered him to climb the hill and pluck the roses he would find on the top of it. Though the Indian knew there could be no roses on the stony summit, especially at such a time of the year. He did as he was told by his mistress, as he used to call our Blessed Lady, and very soon came down to where she was standing with his cloak full of what tradition describes as rosas de Castilla frescas olorosas y con rocio...Our Lady took the roses in her hands and after gazing a while upon them gave them back to Juan Diego, who put them into his tilma.
St. Juan Diego then approached the local bishop and let his tilma open. When the roses spilled out, a beautiful image of Our Lady of Guadalupe was imprinted on his cloak and remains on the tilma to this day.
December 12 is the anniversary of this remarkable event and the "miracle of the roses."