Zos Habracha and biodynamic agriculture

Summary: Are there plants which grow, and fruits which ripen, based on moonlight, rather than sunlight?

Post: In Zos Habracha, we read:

יד  וּמִמֶּגֶד, תְּבוּאֹת שָׁמֶשׁ; וּמִמֶּגֶד, גֶּרֶשׁ יְרָחִים.

14 And for the precious things of the fruits of the sun, and for the precious things of the yield of the moons,

Rashi offers two explanations:

	גרש ירחים: יש פירות שהלבנה מבשלתן ואלו הן קשואין ודלועין. דבר אחר גרש ירחים. שהארץ מגרשת ומוציאה מחדש לחדש:

The first is that there are fruits which are ripened by the moon, namely pumpkins and cucumbers. The second is that גֶּרֶשׁ יְרָחִים means the produce of months, that the land casts it out and brings it out from month to month.

In likewise manner to the first explanation, Rabbi Yosef Ibn Caspi writes:

"The meaning of גֶּרֶשׁ is that which is cast out of the earth, from its belly -- that is to say, the growths which go out of it. And some are dependent upon the sun, and some are dependent upon the moon, as is well known to all workers of the ground, and all the more so to scientists."

Is this really so, that some plants grow on moonlight rather than sunlight? Ovdei adama, workers of the ground, might develop and intuition, or practical experience with this. But on the other hand, they might also develop superstitions. And the chachmei hateva, scientists, of Ibn Caspi's time might be right. But they might also have erred. They could be relying on unreliable Greek science, based on sevara rather than methodical experimentation.

Even if it is scientifically and practically incorrect, this does not mean that it is a bad peshat in the pasuk by Rashi and Ibn Caspi. Running with a statement Ibn Caspi makes elsewhere, dibra Torah kilshon benei Adam, the Torah speaks with the assumptions and beliefs of people.

Here is a bit on scientific astrology of the medieval period:

Here is some folklore about growing cucumbers in the moonlight, from the Frank C. Brown Collection of North Carolina Folklore, part two:

And at Yahoo Answers, while the accepted answer is that moonlight does not help plants grow, see what one person wrote:

It is very true....if anything is planted at the time of the start of a new moon, right through to a full moon, those plants, trees, vegies, whatever, will indeed grow faster, bigger, and will be so much better and healthy looking, than if you were to plant anything after that. My grandfather was a successful Devon cattle breeder, and his vegie garden was simply superb, and he always "planted by the moon", and he certainly was not one given to idle fairy tales, he was very successful in whatever he did, and knew what he was talking about.[ that does'nt mean you can only plant at night time, no....it means you can plant in the day light, but as the moon is getting larger, so will everything else be so.] and by the way....that also applies to getting haircuts, shaving legs and etc,. If you dont want your hair to grow quickly, then do it as the moon is waning. You see the effect the moon cycle has on tides? Well...there's obviously something in it.

What about modern scientists? A passing reference in a Popular Science from 1928, that this view has been rejected by scientists:

There is, however, a strong pseudo-science that moonlight, and when in the moon's phase one plants, has an impact on growing. This pseudo-science is part of biodynamic agriculture.

Astronomical planting calendar

The approach considers that there are astronomical influences on soil and plant development, specifying, for example, what phase of the moon is most appropriate for planting, cultivating or harvesting various kinds of crops.^[20] This aspect of biodynamics has been termed "astrological" in nature.^[21]

See here for an article about how wine growers are subscribing to this stuff, and here for a blogpost blasting it as pseudoscience.

On the other hand, at How Plants Work, see this post and this post about whether, and how, the moon affects plants. Namely, how low light intensities can affect flowering more than complete darkness. Even so, this is a far cry from moonlight being the basis for the plants' growth.