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.
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”.
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.
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.”
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?
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.
Some extra, actual studied information: https://www.mdpi.com/2073-4395/10/7/955/htm
I only read the conclusions, but you might get better insights from it to further educate people following folklore 🙂
Thanks for posting that link.
The science section concludes that “to date Moon has not been proved to affect plant biology regarding consolidated physics.”
In the overall conclusion: “the Moon’s gravity on the Earth cannot have any effect on the life cycle of plants due to the fact that it is 3.3 × 10−5 ms−2, almost 300,000 times lower that the Earth’s gravity; (ii) since all the oceans are communicated and we can consider their size being the size of the Earth, the Moon’s influence on the tides is 10−6 ms−2, but for a 2 m height plant such value is 3 × 10−13 ms−2 and, therefore, completely imperceptible; (iii) the Moon’s illuminance cannot have any effect on plant life since it is, at best, 128,000 times lower than the minimum of sunlight on an average day; (iv) the rest of possible effects of the Moon on the Earth (e.g., magnetic field, polarization of light) are non-existent.”
I read more than just the conclusion, but didn’t still quite understand which factors could be alternative explanations to all of Barlow’s findings on this matter. Is there some good criticism on his work?
Sorry I wasn’t there for you. Every time this superstitious gobbeldy goop shows up in my garden group I want to scream.
Great post. I included it in a FB group having to do with informal planting where tons of people swear by moon phase planting but don’t know how or why or even agreeing among themselves. 🙄
I’m waiting to be castrated… 😆
I went on a search for this info and then thought, “Wait a minute, you should’ve STARTED with gardenmyths.com.” Thanks!
Meant to add to the post – this is the same with plants and the liquid inside them is affected by the moon.
Why not try an experiment – take 2 identical healthy plants and plant one when the moon is full and the gravitational pull is strongest. All it’s energy will be pulled out to the leaves away from the roots.
Then using your moon calendar for best planting time- plant the twin when all the energy and goodness has gone back down to its roots.
You will see a difference in which plant will thrive better and quicker. I have tried this experiment and it worked! So I now use this for best time to plant and to harvest.
Why would I waste my time testing something that clearly can’t work?
So two plants constutes an experiment?? Nope that’s still anecdotal.
plant 500 of each and come back and show the results. Ohh and explain how it pulls “energy” from the roots and how it got in the roots in the first place.
You know, there are some good layman level books on plant biology out there..
There is no difference in gravitational pull between full and new moon. The only difference between these two phases is the level of illumination. The moon is not “gone”, it is still in the sky (at new moon mostly during daylight hours), you just can’t see it.
Energy?? What energy? Do you mean that hocus pocus new Ager, magic crystal energy? What utter nonsense! Plants have a circulatory system, the Moon pulls NOTHING. You really need to read up on some plant biology.
2 identical plants will both experience the same gravitational effects from the moon unless you have found some way to block gravity for one of them. ie you have reinvented Cavorite.
Haven’t you heard of the full moon affecting menstruation too? and basically all water in our bodies. Some hospitals still will not perform operations during full moons because of increased bleeding.
I doubt that – but willing to look at your evidence.
I’ve personally notice an almost extreme difference in plant growth around the new moon, and an almost extreme halt in growth around the full. Citing my own personal observations.
We always plant by the moon. Ever seen an onion 8″ across or a tomatillo 5″ in diameter? We have.
Next we’ll be hearing Roundup Ready crops are scientifically proven to produce more with less water and zero environmental impacts/health consequences. Oh, wait, we already do.
In Trinidad they say don’t dig dirt on a full moon some how d dirt does need more
Did Perry ever get back to you with results of the experiment?