John Napier III has written a fine article on Confederate Memorial Day, in which he tells that at the end of four bitter years of conflict about 350,000 Confederate soldiers lay dead, scattered throughout Dixie, an area the size of Western Europe. He goes on to say that their "still-militant" Southern women determined to honor their fallen men, some of which had not been buried properly after ruinous battles.
Spontaneous efforts sprang up throughout the late Confederacy to honor the South's fallen warriors. Columbus, Georgia, Columbia, Vicksburg, and Charleston South Carolina, as well as Petersburg, Virginia all claim the honor of the First Memorial Day observances.
What we know for sure is that one year to the day after the surrender of the last sizeable Confederate army, on April 26, 1865, Confederate Memorial Day was observed in these and other cities. It was proclaimed "the South's All Soul's Day" and coincided with the blooming season in the South so flowers were available to decorate graves.
Decoration Day began in the North on May 30, 1868. The North chose that date because May 30, 1866 was when the last Union Army volunteers were mustered out, and the flowers bloomed later up there.May 30th later became the "National Memorial Day", and this is the reason for the two different dates. Many states in the South still celebrate Confederate Memorial Day, including Alabama.