Does Planting With The Moon Work?

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Robert Pavlis

The idea that the Moon affects plant growth is an old one that is believed for many moons. It can be found in the folklore of ancient societies ranging from the Celts in Britain to the Maoris in New Zealand. Roman historian, Pliny the Elder, in his History of Nature, Book 18, gives much advice on planting by the moon phases. Today, it is still a rural tradition and in most countries you can buy moon gardening calendars.

The lunar experts suggest that you pick fruit at the full moon for the market as it will weigh more and pick at the new moon for personal consumption because the fruit stores better. Seeds also germinate faster when planted under the right phase of the moon.

A picture was posted recently in a Facebook Group showing a Planting by the Moon calendar on sale. I made a comment about being surprised people still believe in such things. That was a big mistake. Dozens of people jumped on me for not being a believer. How dare I say anything derogatory about what granny believed. Not one person came to my defense. The belief in planting by moon phases is still very common.

Planting by the moon phases
Planting with the moon phases

What is Planting by the Moon?

The Garden Media Group says that gardening by the moon is growing in interest again and is “more than just a phase”.

Soil Science for Gardeners book by Robert Pavlis

The main idea is that moon cycles affect plant growth and moisture in soil, in the same way as their gravitational pull causes tides to rise and fall. Seeds absorb more water during a full moon and therefore germinate better and grow stronger. Different time periods during the phases of the moon are better for planting specific crops.

A variety of sources publish annual planting calendars that will guide you to plant at the right time. This simple “Planting with the Moon” chart from Amazon is a great tool for this (this is an affiliate link).

Moon Gardening Calendar

The four main stages of the moon cycle are the new moon, waxing moon, full moon, and waning moon. The new moon is not visible because the earth completely blocks the sun light from hitting the moon’s surface. The waxing moon is crescent-shaped and is slowly getting bigger. The full moon is fully round and very bright which is then followed by the waning moon which is also crescent-shaped but getting smaller each day.

New Moon Gardening Guide

Moisture in soil is high and moon light is increasing making this a great time to plant. Seeds germinate easier and the extra light makes plants grow faster. It is an especially good time for plants that make seeds outside of the fruit, like lettuce, cabbage or spinach.

Waxing Moon Gardening Guide

Moisture levels are dropping but light continues to increase which helps plants grow foliage. The best time for planting is 3 days before the full moon and is most suitable for plants that have seeds inside their fruits, such as peppers, tomatoes, beans and squash.

Full Moon Gardening Guide

Moisture in soil is high again which helps plants, but the light is slowly decreasing, slowing growth. This is the perfect time to plant root vegetables like carrots, potatoes, rutabagas and beets, and to plant bulbs and perennials.

Waning Moon Gardening Guide

In this final moon phase the gravitational pull is low resulting in low water levels. Moon light is also low so the garden is resting and it’s a poor time to plant seeds. Focus instead on other gardening tasks like transplanting, fertilizing and pruning. Mowing the lawn at this time slows down its growth so you don’t have to mow as often.

4 phases of the moon with trees under each one showing how the moon pulls sap in the tree.
Gravitational effect on sap and water movement in plants, source: Mayoral et al

Do These Guides Make Sense?

Why would seed from plants who make seeds inside a fruit and outside a fruit need different levels of moisture in the soil?

If moon light helps seedlings grow, why would you not plant everything at a full moon and just water a bit more?

If these moisture levels are of value, why would you plant transplants when moisture is at the lowest level?

Planting With the Moon – The Biological Clock

Mammals, including humans, have an internal timing mechanism called the biological clock which controls circadian rhythms on physiology, biochemistry and molecular events. We all know how screwed up our system gets when we fly across time zones. It has now been shown that plants do have a internal circadian rhythm.

The fact that they have a biological clock is not proof that changes in moon light affects plant growth.

I recently visited the Organic Conference in Guelph Ontario and looked at some Moon Calendar Books. It said, “plant beans on June 2, but don’t garden after 11:30. In the UK and Ireland, add a week”.

So in the UK, which is mostly zone 8, you should plant beans a week later than here in my zone 5 garden! And, you better not sleep in or you’ll run out of time.

The Moons Gravitational Pull

Isaac Newton’s laws of gravity explains that tides exist because the water in the oceans is being pulled by the moon’s gravity. Both the moon and sun pull on earth but since the moon is so much closer it has a greater effect than the much larger sun. Our oceans are affected the most when the moon and sun pull from opposite sides of the earth (full moon), or when they pull from the same side, resulting in higher tides (new moon).

If the moon can pull water in the ocean to cause tides, surely it also affects the water in plants and in soil. It is claimed that at the new and full moon more water is pulled to the surface of the soil which has the effect of speeding up the germination process. I found this statement on line, “a lunar gardening calendar that combines the best moon phase and sign together will help you achieve optimum results”, and it comes as no surprise that the website that makes his claim also sells lunar calendars.

Let’s return back to earth and look at the facts. The moon definitely affects ocean tides and produces waves. It also affects everything else on earth, but, and it is a big but, the effect on most things is so small we can’t see it and in many cases can’t even measure it. We don’t see the tides on small lakes because wind and currents from incoming rivers have a much greater effect than gravity from the moon or sun. On Lake Superior, which is the third-largest freshwater lake on the planet, the tidal influence is only two centimeters.

I could find no scientific evidence to support the idea that water levels are raised in soil during different phases of the moon nor is there evidence that the moon or sun affects the water level inside plants.

Claimed Research

A lot of the material on the internet refers to a 10 year study by Dr. Frank Brown, of Northwestern University. He found that in lab studies, plants absorbed more water during the full moon.

None of the dozen or more sites that refer to this work provided a reference. I have seen this before with other topics. People like to quote scientific studies to validate their belief without ever looking at the work. Dr. Brown did study the moon’s effect on animals, so the plant study may exist. If you find it, let me know.

The Science of Moon Gardening

There is scientific evidence that moon light does affect plants. The extra light can affect plants directly, and insects feeding on plants are also affected. But these effects don’t correlate with phases of the moon the way that is claimed by people gardening by the moon.

Lunar cycles do affect certain species, including some herbivorous insects which are dependent on moonlight for feeding.  During the full moon, such insects feed more heavily and affected plant populations retaliate by altering the digestibility of their tissues.

The moon reflects sunlight at a very low intensity, which is negligible even at its peak and far below the level of photosynthetically active radiation (PAR) required to support photosynthetic growth of organisms on the ocean or land surface. The only plants that use moon light for photosynthesis are certain types of phytoplankton which are not normally found in gardens.

Here is what one review of the scientific literature said, “We found that there is no reliable, science-based evidence for any relationship between lunar phases and plant physiology in any plant–science related textbooks or peer-reviewed journal articles justifying agricultural practices conditioned by the Moon. Nor does evidence from the field of physics support a causal relationship between lunar forces and plant responses. Therefore, popular agricultural practices that are tied to lunar phases have no scientific backing.”

two sets of seedlings, the one with moon light has grown larger
Effect of moon light on seedlings. Ones exposed to FML (full moon light) have grown larger than those left in the dark.

A newer study looked at the effect of full moonlight on plant cell biology and found that “despite the low-intensity light emitted by the moon, it is an important environmental factor perceived by plants as a signal, leading to alteration in cellular activities and changes in epigenetics”. Exposure of mustard seedlings to full moon light for 3 consecutive nights resulted in more growth than exposure to darkness. The seedlings were not grown to maturity to see if the light actually affect yield.

Biodynamic Agriculture

“In Biodynamic agriculture the entire farm, the surrounding terrain, the influences of the waning and waxing moons, even the positions of the stars are all seen as integral to soil health and crop vitality. ” They never went on to explain how the moon and stars affect soil health.

Different Moon Systems

Although many people believe in gardening by moon phases it is not common knowledge that there are actually three different belief systems.

Moon Phases

The more common one is based solely on the phases of the moon. Jackie French explains it well, “Plant growth is supposed to follow the increase or decrease in the Moon’s light. So you plant crops or pick grapes during the waxing (increasing) phase, and harvest crops or cut timber during the waning phase. A refinement says you plant crops like peas whose yield is above ground during the waxing phase, and crops like carrots whose yield is below ground during the waning phase. Note how the refinement contradicts the original view. Other contradictory views exist. Thus one says you should sow seeds just before New Moon so the seeds will germinate and start growing in the waxing phase, while another more widespread view says you should sow seeds just before Full Moon. They can’t both be right.”

Moon Phases and Zodiac Signs

Since the moon passes through the signs of the zodiac it is only natural to conclude that they also affect plants. This belief is more fine tuned and takes both systems into account to decide the right time to plant and harvest.

Sidereal vs Tropical Moon Signs

In this system it is believed that sidereal moon signs are more important than tropical moon signs – whatever they are?

Which System is Right?

In my mind this is one of the big problems with this whole story. When you have three competing beliefs and even the believers can’t agree on which one is true, it really makes you wonder if any of them are valid. If one of these really worked, would someone not be able to show that it worked better than the other two?

Professor Stefan Buczacki, the former chairman of Gardeners’ Question Time on Radio 4 has been quoted as saying “It’s baloney,” he says. “If there was anything seriously in it, why over the centuries has not every gardener or, more importantly, every horticulturalist, followed these maxims? Why is it that people who plant by the moon don’t win all the prizes at the shows, or develop all the new varieties?”

Is Frost More Likely During a Full Moon?

Garden Myths - Book 1, by Robert Pavlis
Garden Myths – Book 1, by Robert Pavlis

This is a myth I believed for a long time. I discuss it more fully in my book Garden Myths but the bottom line is that there is no correlation between full moons and frost.

Full Moon and Lunacy

But surely it must be true that during a full moon people act more irrational, cause more murders and have more visits to hospital emergency rooms? No, that is not true either.

There is no support to the idea that the phases of the moon affects things like, births, heart attacks, deaths, suicides, violence, psychiatric hospital admissions and epileptic seizures.

Man has come up with many crazy theories about the moon and none are true, not even werewolves.

Rational Thinking About Moon Gardening

Non-believers plant according to calendar dates that reflect the last frost date. In my area the last frost date has always been around May 24. Global warming has thrown that out of whack, but I wanted to see how well the phases of the moon correlated with this date.

I got the date of the full moon that was closest to May 24, for each year between 2000 and 2020. The earliest was May 13 and the latest was June 9. That is a variation of almost 4 weeks.

Even with the current erratic weather the last frost date does not vary that much. Planting by the phases of the moon will surely get warm growing crops killed in some years.

What about other planting zones? Lets assume the phase of the moon is perfect for planting in my garden. Gardeners that are 2 zones warmer or 2 zones cooler will have the full moon on exactly the same day. Is it reasonable to think  that the weather and last frost date will be the same in all of these zones?

This is one of these myths that just does not make sense. Why then do so many people believe in planting by the phases of the moon?

I used to believe that frost is more likely on a full moon, but as soon as I saw the data it was clear that my belief was wrong. I no longer believe it. Wouldn’t it be great if the world started believing in facts? Most disagreements and conflicts would end.

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

69 thoughts on “Does Planting With The Moon Work?”

  1. I’m currently on the “moon phases can’t affect planting” train, but I did look up that article that was referenced and found a copy here.

    https://archive.org/details/biostor-9154/page/269/mode/1up

    Most of it went right over my head, though the fact that it’s from the 70’s and hasn’t been replicated by another study makes me wonder if their 20-bean samples were enough to make this statistically significant.

    Reply
    • Thanks for posting the link.

      1) This experiment measure water absorption by dry beans after a brief soak in water. It does not measure germination or plant growth.
      2) It is missing stats on the data, so hard to tell how significant the differences are.
      3) It shows high points at new moon, full moon and half way between the two. Compare that to the cycles of the moon attracting water form high and low tides – they are high only at new and full moon. https://www.weather.gov/jetstream/tides
      4) Effects inside a grow chamber and outside are quite different?

      I don’t think it supports the idea that planting by the moon is beneficial to plants.

      Reply
  2. I notice that those who have done their own informal experiments on this believe it works in varying regards, and those who have not done their own experiments smugly reject the others due to lack of scientific rigor.

    Contrast this to the way that the subject of no-till was handled by Robert… well, he is a practitioner of this practice, has personal experience, so came out largely positive in his assesment of the practice, despite a lack of scientific backing to fully form his conclusions.

    I deduce that if he tried germinating onions a few days before a full moon, vs. at the first quarter, as I have, he might enlighten himself without having to get a double Phd in physics and plant biology, recieve the backing of a prestigious university, recieve the grant funding, write the journal article, get it published, and survive the review of his peers. To go to all that trouble would be stupid, but it seems that is what Robert is suggesting, rather than running a $1 simple test in the basement or on the porch.

    In my experience, the moon phase makes a difference in some things and not in others. No bold claims here, but I’m also not relying on a lack of relevant scientific literature to disprove what observant curious gardeners may have been directly observing for millenia.

    Reply
    • You made two major mistakes in your analysis.

      1) The so called “informal experiments” were not experiments. They are just peoples anecdotal opinions. Show me a documented experiment that meets the criteria of both controls and measurements in support of planting by the moon. Until you have that you do not have informal experimental results.

      2) You assumed there is a “lack of relevant scientific literature”. That may be true for planting before and after a full moon, but there is a huge body of scientific literature about how plants grow. There is also a lot of scientific literature in physics about how the moon affects things on earth. Based on what we know there is no support for the idea of planting by the moon.

      Reply
  3. What do you think of the idea that moon planting always was a sociological phenomenon rather than an agronomic one? “Plant your spelt at the second quarter of the fifth moon of the year.” may have meant just as much to a preliterate neolithic farmer as ” The optimum time to plant your crop is the second week of May” means to a modern farmer reading a Department of Agriculture website. A local ‘wise person’ could be given this important knowledge at an annual gathering and could establish the solstice from a standing stone and count off the moons on a notched stick.
    As to why people still use it, why not if it is harmless? It is colorful and obviously a talking point. Gardening is as much an art as a science and not everything we do has to be rational.

    Reply
    • “As to why people still use it, why not if it is harmless? It is colorful and obviously a talking point. Gardening is as much an art as a science and not everything we do has to be rational.”

      People are always free to do what they want. I have never heard a scientist tell people they should not use the moon phases to optimize agriculture, nor have I heard one saying that it should be forbidden to use homeopathy.

      But the followers of such beliefs make affirmations, and some skeptical people simply reply to these affirmations by looking at facts, or maybe some reply with other beliefs of their own (not everyone has to be right). This is just discussion and no one is forbidding anyone to do anything.

      It is interesting to note the defensive atitude of believers. Simply presenting a different opinion (based on facts) seems like an attack on them, denying their freedom to believe what they want. Does respecting an opinion means we should never contradict it? And does contradicting an opinion necessarily mean that we don’t respect it? If telling someone they are wrong should be forbidden out of respect for them, how many things would change in society? How would science work if we could not contradict each other? There would be no technology, there would be no politics, maybe only one dictator. Society’s progress has always relied on contradiction.

      Should it be considered a personal matter? No. They are saying that this or that works. They are not talking about their personal life, they are talking about the world we all live in. They are making a statement about our world, and just like them we are allowed too to make our own statement about that world. Note how strange it is that it is considered very offensive to say in front of religious people that there is no god, but it seems very acceptable for religious people to say in public that god does exist. Contradicting the belief of a religious person is wrong, but contradicting the belief of an atheist is almost ok. Yet both have heard a statement going against their belief. If someone says that the moon affects plant’s growth, it goes against my belief and I have the right to respond, just like they have the right to respond to anything I say. I might be wrong but it seems to me that only irrational beliefs are defended using this method.

      Reply
      • ignorance is merely a lack of knowledge. Stupidity is refusing knowledge they disproves false beliefs. We have a right to believe what we want, we do not have a right to foist falsehoods onto others. Dispelling myths in all things is a worthy goal.

        Reply
  4. My parents follow it, for they say it’s more likely to get water ( I guess that’s the “pulling the water up).. But I then see them water every day… Yeah maybe if you have 100 acres and you cant water, but not for your backyard gardener.
    OH, as mentioned above, the weather has way more effect. When I ask them about stuff like that, they simply fluff it off by saying one didnt know the forecast 100yrs ago…

    Reply
    • First sentence of the conclusion is “At present, the evidence for a lunar or a lunisolar influence on root growth or, indeed, on any other plant system, is correlative, and therefore circumstantial.” ie no evidence yet.

      Reply
      • This falls exactly in line with what you wrote: “People like to quote scientific studies to validate their belief without ever looking at the work.”

        Obviously the commenter did not even bother to read the research before posting the link saying it supports the idea.

        Reply

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