Green week is an ancient Slavic fertility festival celebrated in early June and closely linked with the cult of the dead and the spring agricultural rites. In Russian villages, the seven weeks after Easter were a time of festivity, and Green Week took place during the seventh week. The Thursday of that week was called Semik and included burial services for the uncleandead. Green week is also called Trinity Week in Russia, and Whitsuntide week in Britain. The end of Semik inaugurated the celebrations of Trinity Sunday, which came three days later. On Semik, funeral rites were held for the unclean dead. Birch trees were particularly significant to the holiday, because they were considered hosts for the souls of the deceased. Sometimes people would honor a particular tree by decorating it or carrying it around, while other times people would cut birch branches and hang them in their home. The birch was also seen as a symbol of vegetative power, and may have been honored with the hope of bringing its vitality to the coming season's crops. Springtime and fertility rituals were also important to the holiday. Girls brought offerings of fried eggs and beer to birches, and spoke charms about improved harvest when weaving garlands for the trees. Another tradition is for girls to pledge vows of friendship before the chosen birch tree. Some believe this to be the remnant of ritual sexual activity associated with the cult of spring. Like Kostroma during Maslenitsa, a chosen birch tree was destroyed at the end of the festivities. Usually, it was drowned "in order to provide the needed rainfall for the sprouting crops". The rusalkinature spirits were another important figure to Green Week traditions. Some believe they were associated with deceased family members, or perhaps only unclean dead. Sometimes an honored birch tree would be named for a rusalka as part of Green Week. Some of the rites of Green Week were thought to placate the rusalki so they would stay away from the village's agricultural fields for the season and thus not bring them harm. The rusalki are also associated with water and fertility, and so may be invoked during Green Week in an attempt to bring their moisture and vigor to the fields. During Green Week, rusalki were believed to be more active, making them a greater threat to villagers. One precaution villagers took during this week was avoiding swimming, because rusalki were thought to live in the water and might drown passers by. There is a similar holiday celebrating Pentecost in Romania, called Rusalii. Also in Germanic tradition there is a similar tradition, for example, Pfingstbaumpflanzen in Germany. In modern-day Poland it is celebrated along with Pentecostal Sunday as Zielone Świątki.
