These events took place around Passover time, but to commemorate them then would be a distraction from the theme of the Crucifixion and Resurrection of Our Lord. They are accordingly celebrated on 1 August, the anniversary of the dedication of a church which was said to possess a length of the chain with which Peter had been bound.
In English-speaking countries 1 August is also Lammas Day, or loaf-mass day, the festival of the first wheat harvest of the year, on which day it was customary to bring to church a loaf made from the new crop. In many parts of England, tenants were bound to present freshly harvested wheat to their landlords on or before the first day of August. The blessing of new fruits was performed annually in both the Eastern and Western Churches on the First, or alternately the Sixth, of August. The Sacramentary of Pope Gregory (d. 604) specifies the Sixth.
The custom of giving thanks for the harvest is undoubtedly older than Christianity, and probably loaves were offered in worship in Britain around 1 August before Christians took over the practice. Hence it is neither surprising nor particularly significant that the Wiccans have a harvest feast on 1 August. (Some critics say that this proves that Christianity is nothing but a collection of recycled pagan superstitions. I say that it is evidence that the climate of Britain, and therefore the usual time of harvests, was not altered by the coming of Christianity.)
LinK:http://elvis.rowan.edu/~kilroy/JEK/home.html