The earth takes twelve months to pass through all twelve constellations in the zodiac. The moon does this in about 27 days. Each time that the moon enters a different constellation, the type of day changes. Each day on the Biodynamic calendar corresponds with the type of elemental sign. For example, Leo is a fire sign, and when the moon is in the constellation of a fire sign it is a fruit day. So, when the moon enters Leo, the plants are working on producing fruit (and bees are gathering nectar.) Another example is Scorpio is a water sign, and when the moon enters said constellation, leaf day begins. Those days the plants are working on making bigger leafs and producing more chlorophyll (and bees are making honey.) Air signs are flower days, and the plants are in floral production (the bees are gathering pollen.) Earth signs are root days, where the plants are digging firmer foundations (and the bees spend this time building honey combs.)