Each year takes the next planet on a seven-year wheel, so every seventh year shares a ruler
The calendar gives each year to one of the seven planets the old astronomers could see move, taken in the Chaldean order of Saturn, Jupiter, Mars, the Sun, Venus, Mercury and the Moon. One planet rules one year, the next planet takes the following year, and after the Moon the wheel goes back to Saturn.
Knauer read each planetary year from the start of spring to the end of winter, so a year runs from about March to the following February. Modern editions and the German press label the years by the calendar, and so does this tool. The same Chaldean order sets the planetary hours of every day, and the planetary hours calculator shows which planet rules the hour you are in now.
An abbot kept seven years of weather notes in the 1650s, and German papers still print his forecast each year
Mauritius Knauer, abbot of the Cistercian monastery of Langheim in Franconia, kept weather records from about 1652 to 1658. He held that each year fell under one of the seven planets and that the weather would come round again when the same planet returned seven years later. He wrote his notes up as a perpetual household calendar to help the monastery plan its sowing and harvest.
Knauer died in 1664. In 1700 Christoph von Hellwig, a physician in Tennstedt and later Erfurt, printed an extract of the manuscript, and from 1720 the editions came out more and more often under the title Hundertjähriger Kalender, the Hundred-Year Calendar. W.D. Gann classed years by a ruling planet in his own weather research and read each type of year against the supply of grain, feed and fuel.