Dr. Frank Brown of Northwestern University performed research over a ten-year period of time, keeping meticulous records of his results. He conducted his experiments in a laboratory with no direct moonlight, yet he found that plants absorbed more water at the time of the full moon.
John Jevons, author of “How to Grow More Vegetables” adds that when plants do have direct exposure to moonlight, the increasing light of the waxing moon stimulates and increases leaf growth, while during the decreasing light of the waning moon leaf growth slows and energy returns to the plant’s roots.
Further tests have been conducted, most notably by Lily Kolisko in Germany in 1939 and by Maria Thun in 1956. Thun found maximum germination on the waxing days just before the full moon and was surprised to discover that the signs of the zodiac played their part as well. She experimented with a variety of crops: carrots and parsnips (roots); lettuce, spinach, and corn salad (leaf); beans, peas, cucumbers, and tomatoes (fruit/seed); zinnias, snapdragons, and asters (air). Crops responded well when planted in the appropriate sign for their type of plant; cucumbers sown on leaf days had strong leafy growth, but did not produce many flowers.
There were some exceptions, of course. For instance the brassica family (broccoli, cauliflower, etc.), which one might consider a flower rather than a leaf, favored being planted on leaf days (water signs). Their tests also indicated that responses to lunar planting were heightened when planted in organic soil that had not been treated with synthetic fertilizer or pesticides.
More information is available on our citations and further reading page, which we update as our research continues, or over in our blog, where we track our own experiments on lunar planting, and where all of our data is available for you to examine and judge for yourself.