I was learning the Ukrainian months today. They are so nice.
January: січень = rod/pole
February: лютий = very cold
March: березень = birch
April: квітень = flowers
May: травень = grass
June: червень = worms
July: липень = limetrees
August: серпень = sickle
September: вересень = heather
October: жовтень = turning yellow
November: листопад = falling leaves
December: грудень = frozen ground
These are the old Slavonic names for the months, which are preserved in Czech, Slovak, Croatian, Ukrainian, Polish (mostly).
Russian, Serbian and Bulgarian adopted the latin based names for months, as has English.
My question is, when did it happen in Russian?
This is one of the major difference between Serbian and Croatian, often considered to be dialects of the same language. Serbian has Latin based months, whereas Croatian has Slavonic based months.
In Polish, the Slavonic months have been preserved, except in March and May, where we find marzec and maj.