In past years if Easter was late or we were at La Railliere for the May Day bank holiday, when we put our geraniums outside for the coming summer, we got quizzical looks from our elderly French neighbours. Later we learned from a French friend that we should not put our plants out until after 14 May.
Why? Apparently throughout France and across several European countries, farmers have invoked the help of three Saints, Mamert, Pancras and Servatius to help guard their crops against sudden frosts. Their feast days are on 11, 12 and 13 May respectively. In colder parts of France a further saint (St Urbane whose feast day is 25 May) is added.
Who were these saints?
St Mamertus was the Archbishop of Vienne in Gaul. He introduced 3 days of prayer and processions prior to Ascension Day ( termed Rogation) to ward off those frosts. He apparently came from a wealthy family in Lyon and died in AD 475.
St Pancras was a Roman who converted to Christianity and was beheaded at the age of 14 in AD 304. He was a nephew of St Denis.
St. Servatius, who died in AD 384 was considered a great diplomat and was renowned for his holiness. It is said his grave remained clear of snow whilst all areas around were covered in snow.
So what is so special about these 3 days in May? There are several theories.
In France these days are included in a period from 21 April to 20 May when the appearance of the moon is called "la lune rousse". Rousse refers to roussir which means to brown that is the frost damage which turns green shoots brown. The period follows Easter when nights are often cloudless.
Some meteorologists think around these days warmer air over Central Europe comes in contact with cold air from the Atlantic, causing temperatures to plummet over Central Europe.
Some astronomers think that around these days the Earth passes through dust clouds which deflect some of the Sun's rays causing temperatures to fall.
In the UK the period is called a "Blackthorn Winter" when the blackthorn's pale blossoms are in full bloom matching the frosty bushes and grass all around. The blackthorn has the reputation as being a witches tree.
So what's the truth about it all, well certainly cold spells around these 3 days in May are not unusual. Is this due to the 3 Saints?
The Catholic Church does not think so as in 1960 it removed these saints from duty as they sought to remove what was probably a pagan tradition.
Also the change in 1582 the change from Julian to the Gregorian calendar added 10 days to the dates so the periods would now be May 22-25.