Maria Thun : Biodynamic Almanac
The twelve constellations are grouped into four different types [Root, Leaf, Flower, Fruit] and the moon passes through the various types over time.
Plants are sown, cultivated for maximum quality during their "group" times
Examples:
Root: radishes, beets, carrots, potatoes, onions
Leaf: cabbage, lettuce, spinach, parsley, herbs. For harvest and storage fruit/flower times are best.
Flower: all flower plants; spraying 501 preparation; oil bearing plants-ie sunflower note: broccoli
Fruit: beans, peas, maize, tomatoes, cucumbers, pumpkins, cereals