Isaac Newton established the laws of gravity, which proves the tides are affected by the gravitational pull of the moon. The pull of the moon is stronger than the sun because, even though the sun is larger, the moon is closer to the earth. The strongest effect is felt when the moon and sun pull from the opposite sides of the earth, at the full moon phase, although it also creates high tides when they are on the same side (at the new moon) as well.
“The gravitation of the passing moon pulls the nearest body of water a little away from the solid mass of earth beneath it, and at the same time pulls the earth a little away from the water on the farthest side. In this manner the moon sets up two tidal bulges on opposite sides of the earth.” (Louise Riotte, 1)
These same forces affect the water content of the soil, creating more moisture in the soil at the time of the new and full moon. This increased moisture encourages the seeds to sprout and grow.
Dr. Frank Brown of Northwestern University performed research over a ten-year period of time, keeping meticulous records of his results. He found that plants absorbed more water at the time of the full moon. He conducted his experiments in a laboratory without direct contact from the moon, yet he found that they were still influenced by it. (2)
Rudolf Steiner was the founder of the anthroposophical movement, which sees a correlation between science, nature, universal laws and spiritual concerns. Out of this movement the Biodynamic methods of planting were developed. He established a relationship between the elements of earth, air, fire, or water that corresponded to specific parts of the plants. Earth corresponds to root, water to leaf growth, fire to seed production, and air corresponds to flowers. Hence, when planting crops for their fleshy roots, you would plant them in an earth sign, and so forth.
Biodynamic methods are based on the heliocentric, or astronomical, position of the moon. This system is more complicated and also takes into consideration eclipses, trine, apogee and perigee as well as descending and ascending moons. (The Gardening by the Moon Calendar is based on the geocentric and astrological calculations.)
John Jeavons, author of "How to grow more vegetables…" adds the influence of the increasing or decreasing moonlight on the growth of plants. When the moon is in it's waxing phases the " increasing amount of moonlight stimulates leaf growth", and " as the moonlight decreases the above ground leaf growth slows down. The root is stimulated again." (3)
Further tests have been conducted, most notably by Frau Dr. Kolisko in Germany in 1939, and by Maria Thun in 1956. They primarily experimented with root crops, showing the effect of lunar phases on seed germination. They found maximum germination on the days before the Full moon. Crop yields were reported by weight.
Thun was surprised to discover that the signs of the zodiac played its' part as well. Thun experimented with a variety of crops: carrots and parsnips represented root crops; lettuce, spinach and corn salad as leaf types; beans, peas, cucumbers and tomatoes as fruit seed types; zinnias, snapdragons and asters were air crops. Crops responded well when planted in the appropriate sign for their type of plant. There were some exceptions, however. Some plants seemed to favor signs other than what would appear to be logical; for instance the brassica family, (broccoli, cauliflower, etc.) which one might consider flowering types, seemed to favor water signs. Cucumbers sown on leaf days had strong leafy growth, but did not produce many flowers. Their tests also seemed to indicate that responses to lunar planting were heightened when planted in organic soil that had not been treated with chemical fertilizer or pesticides. (4)
Ute York, in her book "Living by the Moon" says
“The old-time gardeners say, "With the waxing of the moon, the earth exhales. " When the sap in the plants rise, the force first goes into the growth above ground. Thus, you should do all activities with plants that bear fruit above ground during a waxing moon. With the waning of the moon, the earth inhales. Then, the sap primarily goes down toward the roots. Thus, the waning moon is a good time for pruning, multiplying, fertilizing, watering, harvesting, and controlling parasites and weeds” (5)
Plants sown in the correct combination of the best lunar phase and sign show increased vigor, due to having all the best influences. They are growing at an optimum rate and are not as prone to setbacks that would affect less healthy plants. Harvests are often quicker, larger and crops don't go to seed as fast.
“It is very informative, and understandable, without too much astrological jargon. The calendar is also very easy to use. I am sending it to an elderly friend of mine who has a hard time interpreting the farmer's almanac. She'll love it!"”
“Your calendar is terrific. I use it for my farm garden and to test it out last spring I planted carrots at your direction, then planted the same variety, the same seed batch at a time contra-indicated, and sure enough in the row under your directions the germination was about 95% (tons of carrots! Horse very happy!) and the other row had about 25 seeds sprout...out of about 200 seed planted. I'M STILL PULLING CARROTS IN DECEMBER! Thank you for a wonderful work of magic that really works! "”