The 2013 calendar, now in its 51st year, is adapted for North American (Eastern Standard Time) dates and times.

This useful guide shows the optimum days for sowing, pruning, and harvesting various crops, as well as working with bees. It includes Maria and Matthias Thun's unique insights, which go above and beyond the standard information presented in some other lunar calendars. It is presented in colour with clear symbols and explanations.

The calendar includes a pullout wallchart that can be pinned up in a barn, shed or greenhouse as a handy quick reference. Also included is a memorial to Maria Thun, who died in February 2012.

Maria Thun (1922-2012) was born near Malburg, Germany. Her father had a small farm and the children took part in the farm work. In the early 1940s Maria Thun met her future husband Walter Thun, who introduced her to some biodynamic farmers and Maria became greatly interested in these farming methods. She continued to experiment with sowing during the 1950s with many types of crops to see whether the movement of the moon had the same effect on all crops. From her observations she divided passage of the moon through the zodiac into four: root days, leaf days, fruit days and flower days, each indicating which type of plant is best sown on each specific day.