Gardening by Moonlight

It’s October again; myths and mysteries. We like the Robert Burns account of an old Scottish prayer: Lord, protect us from Goulies and Ghosties and long legged beasties and things that go bump in the night.

This time we want to talk about the mystique of planting crops according to the phase of the moon.

Leon: Let’s be blunt. We are discussing lunar lunacy—the effects of the moon on plants. It may not be pure lunacy—or it may be. Anyhow the discussion is worth a cup of coffee.

Ed: When our friend, Carlos Smith, began working as a County Agent in Marksville he went to visit an elderly gentlemen who was having trouble with his bean crop. He assured Carlos that he had planted the beans properly, during Holy Week, but the crop didn’t look good at all. Carlos saw a few things that seemed to be wrong but wasn’t sure what was bothering the farmer. What seems to be the trouble? “Cher, ever since dey walked on dat dam’ moon, nothing has been the same.”

Leon: Most old-time gardeners have stories of planting root crops in the dark of the moon and fruit crops in the light of the moon. And then, there is the rule of planting important crops during Holy Week. Easter comes on the Sunday after the first full moon, following the spring equinox. So, Holy Week always comes near the time of a full moon after March 21.

Ed: Leon is neglecting another point. Down here in the Country Roads area, March 21 is close to the time of the last killing frost. The date of Easter, and Holy Week, can vary by as much as 40 days but the last killing frost also varies each year. Planting on Good Friday is pretty good insurance against the risk of a late frost.  

Leon: My grandpa, Mike Scott, lived in Michigan and he always planted potatoes on Good Friday. He got killing frosts after that, but short cold snaps don’t affect potatoes very much. Actually, Mike was going against the common wisdom that you should plant root crops in the dark of the moon.

Maybe I should stop rambling and express an opinion. Do phases of the moon affect plant growth, or is it all lunacy? Let’s start with the fact that the only difference between a full moon and a first quarter moon is the amount of reflected light. The gravitational effects of the moon vary with its orbit but not with phases. Plant growth is strongly affected by day length. Many plant species set flower buds in response to long days, and others have the same response to short days. The trick here is that the light of the full moon is strong enough for some (maybe most) plants to detect it as daylight. Could a few days of full moon light cause some plants to form floral buds and prevent others from flowering? Would a plant that is not flowering store more nutrients in the roots?  This is hard to test, because the phase of the moon would have no direct effect on the germination of seeds. The effect would come 28 days later, when the plants have emerged and the light (or dark) phase comes around again.

Ed: Leon likes to ramble over imponderables. He is really stretching a point to say that the phase of the moon at planting time will affect the seedlings one or two months later. Folklore about the effects of the moon is just part of the Southern tradition for spinning yarns. I don’t know what light and dark of the moon means. Does it mean that you should plant on the day before and day after a full moon, or maybe during the entire week when the moon is full?

And, there are a lot of old practices that follow the phases of the moon, with no logic at all. In the dark of the moon you should: deaden trees, kill weeds, rive shingles, split rails, and lay rail fences. The light of the moon is the time to: prune fruit trees, dig potatoes, and slaughter hogs. Those are just yarns, nobody really believes them, but they make good stories.

I agree that there is a strange majesty of a full moon rising just above the horizon. How can it be so large when it rises and so small when it is directly above you? The full moon often seems eerie; it affects ocean tides and makes people wonder about exploring it. Maybe Carlos’ friend was saying that his sense of the wonder and majesty of a harvest moon were destroyed when men walked on it. I agree with him entirely. They shouldn’t have walked on that moon.

Leon: Friends, Ed will gloat all day over having shot me down. He is right, I do enjoy looking for logic in folklore, but the idea of moonlight affecting the photo-period of plants really is far-fetched. When I try to discuss effects of the moon on crops someone usually brings up the mythical “Scientific Study,” showing that there is a strong correlation between the full moon and increases in mental illness, in the numbers of births, suicides, crimes, and prison riots. Friends, that study doesn’t exist. Statistical types of people have tried to locate it, and have looked for data to support it. They found police and hospital workers who felt sure there were fluctuations due to phases of the moon, but their hospital and police records show no lunar effects at all. Statisticians call these ideas attribution errors. That is a new term for me, but it seems to mean that there is an error in the interpretation of data. For example, if you were to plant beans during Holy Week and the crop turned out to be fine—you could attribute that to planting at the right time. But, if a crop planted during Holy Week did poorly because of cold weather, disease, or insect problems, you might ignore that planting because other problems affected the results.

Ed: Leon keeps trying to salvage his credibility, but can’t. Lunatic comes from the Latin lunaticus, meaning “moon-struck.” Back as far as the Greek and Roman eras, people felt that, because the moon affected tides, it could also affect human behavior. Hippocrates, the patron saint of physicians, believed that. “Madness comes from the brain’s moistness.” His logic was if the moon can move water (as in tides), it will also attract water in the body—thus madness is the result of uneven distribution of water in the brain. This idea survived at least into the nineteenth century, with the modification that madness is a disease that is exacerbated by the full moon. As I said earlier, a full moon, rising at twilight, is an awesome scene. I would like to believe it can affect human enterprises—but it ain’t so.

Ed O’Rourke, Jr. and Leon Standifer are not only moon gazers, but the authors of Gardening in the Humid South (LSU Press, 2002), now available in affordable paperback.