Primroses

Myths, folklore, and symbolism
Primroses: These flowers were believed to affect luck in poultry rearing, presumably because primroses and chicks are both bright yellow ('like affects like'). From the mid-19th century to within living memory, children were warned never to bring fewer than thirteen primroses into the house, for this was the optimum number for a clutch of chicks, and fewer primroses meant fewer eggs would hatch. It was sometimes further believed that giving someone a single primrose, or bringing one indoors, would cause death. (Oxford Dictionary of English Folklore)

Do you know of primrose folklore from other countries?