My Grandad always planted his spuds on Good Friday, whenever it fell.
So did mine!
Did you ever know why that date? My granddad worked in the iron ore mines, and I guessed it might be something to do with it not being Sunday, but never knew for sure.
Sorry, he never said, but I think it was quite common.
I'd guess it has a lot to do with people not keeping track of time & dates except by way of the Church calendar. The spuds is the one we remember but there were others.
Not all Church dates now but people here still put the rams with the ewes on Bonfire Night & bring them back in on Christmas Eve. You monitor your hay by having half left by Candlemass (Feb). Lambing starts April Fools day.
If you didn't read & write maybe you at least always knew when Good Friday was?