"Midsummer is one of the major celebrations in Scandinavia, together with Christmas Eve, New Year's Eve and Walpurgis Night. It is a celebration of the Summer solstice, the longest day of the year. In Sweden and in Finland, Midsummer is celebrated as a public holiday during the third weekend of June, when everybody escapes to the country to spend a relaxing time in nature.

The celebration of the Summer solstice is a very ancient practice, dating back to pre-Christian times. Midsummer was originally a fertility festival with many customs and rituals associated with nature and with the hope for a good harvest in the Autumn.
Midsummer's Day was later christianized as the day of Saint John the Baptist, an important Christian saint. Yet, many of the ancient pre-Christian customs that marked the Summer solstice have survived to this day and are still being celebrated in Scandinavia as they were many hundreds ofLike in every major Scandinavian celebration, meeting friends and family is as important as having plenty to eat on the table.
Midsummer traditional delicacies are fresh potatoes with pickled herring or smoked fish from the nearby lake, the first strawberries of the season for desert, and some schnapps and beer to wash down the herring.
In Sweden, Midsommar is celebrated on Friday around the Majstång, a tall phallic maypole covered with flowers and greenery. People gather in the afternoon to raise and to sing and dance around the Majstång, an ancient tradition originally related to fertility rituals. Many women wear a flower wreath on their heads and some people dress in traditional folk costumes. Some regions in southern Sweden also lit bonfires to celebrate the Midsommar."
Midsummer Night was a very important celebration much before Christianity arrived to Scandinavia and some of the pagan Summer solstice folklore remains still alive. Right up to the last century, many people in northern Europe still believed that plants and water had special healing powers during the Midsummer night. Evil spirits were free during that night and bonfires had to be lit to protect the humans against their powers."
"In many parts of Sweden and Finland, many parents send their young girls to pick a bouquet of seven or nine flowers, alone and in total silence. The tradition says that if they put the flowers under their pillow, they will dream of their future husband. Swedish and Finnish homes are decorated with flowers and birch tree branches, once again the importance of a well cleaned house in the Scandinavian culture."
"Midsommar and Johannus' old customs are well alive all around Sweden and Finland, however, the most popular Swedish Midsummer celebrations are found in Dalarna, the islands of Öland and Gotland, the Stockholm archipelago and Bohuslän near Göteborg, while the Finnish equivalents are found in southern Finland and Åland."

Text source from: http://www.scandinavica.com/culture/tradition/midsummer.htm