Moon Phase Planting – Science Says

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Does moon phase planting really work? This gardening in Canada article will look at the science behind planting by moon phases. 

In order to fully understand the moon phases, we need to first look at the history of planting by the moon. This tradition has been around since ancient times for example the Celts in Britain would use this method. It also has been mentioned in Roman texts as a way to maximize food production.

If you are new to this blog my name is Ashley and I am a soil scientist. I am located in a Canadian Zone 3 and a USDA Zone 4. I write articles, make YouTube videos, Instagram & Facebook posts all designed for Canadians and Cold Climate gardeners using science-based methods. If you are looking for anything specific be sure to let me know in the comments down below.

Moon phase experts will also suggest that there are specific times for pruning and fruit picking as well. So what exactly are the rules when it comes to planting by the moon phase?

  • First-quarter moon cycle (new moon to half full) – leafy greens such as lettuce, cabbage, Brussel sprouts and spinach, should be planted. 
  • Second-quarter moon cycle (half full to full moon) – Planting fruit-bearing plants with seeds inside, like tomatoes, beans, peppers, eggplants, Luffa
  • Third-quarter moon cycle (full moon to half full) – Planting root vegetables, bulbs and perennials, like potatoes, garlic, raspberries, turnips, carrots, onions, leeks etc.
  • Fourth-quarter moon cycle (half full to new moon) – Do not plant. Weed, mow and kill pests instead.

The Science – Moon Phase Planting

We know that the full moon can affect mammals and this does include humans. The thought process is that the moon is able to affect our biological clock also known as a circadian rhythm. You can ask nurses, teachers and parents how intense their days can be when there is a full moon.

So the question is do plants have some form of a circadian rhythm that can be ultimately affected by the moon. The answer to that question is not yet fully understood. The general consensus prior to five years ago was that plants did not have a circadian rhythm. New research however is indicating that there is some form of a biological clock within plants. Unfortunately, the effect the moon has on the biological clock is not yet fully understood.

Moon phase effects on the water – small scale

The second thing we know about the moon’s effect on the world is tides. It’s a known fact that the moon is able to affect ocean tides and produce waves. does this mean that the water moving into the seed prior to germination can be affected by the moon?

The answer to this is simply no. The water in smaller bodies such as lakes and rivers is not affected by the moon or its phases. Interestingly enough the great lakes, the largest lakes on earth, have a very minimal effect based on the moon. At most the change in water has only been noted to be around 2 inches. That means on an even smaller scale such as soil water or water in seed it is unlikely to be affected.

Studies on moon phases and plants

People who plant by moon phases will often reference a 10 years study done by Dr. Frank brown from the University of Northwestern. I’ve had a lot of trouble trying to locate this actually published journal so I am unable to comment on its validity. However, I did find some other scientific journals with some compelling information.

Moon Phase Effect Of Plant Water

One interview done with Dr. Barlow noted that plant leaves are partially governed by the gravitational pull of the moon. While this does not affect seed starting it does ultimately affect the plant itself. It was noted that plant leaves rise and fall during the day-night cycles and reaction to light in their environment. This means on nights with a full moon the leaves may sit higher than that of a new moon.

Dr. Barlow goes on to explain that this movement is completely governed by the pulvinus or the “joint” Of the plant. This is specifically where the leaf meets the stem. This means the moon’s gravitational pole may not affect the entire plant but rather just one single area. How this ultimately changes the yield or pruning has yet to be studied.

Dr. Barlow does end off his entire interview with a statement saying: “It’s not really accepted in mainstream science,” and he hopes his paper will encourage people to revisit the idea.

Moon Phase Effects Pollen – Proven

The other interesting study on moon phases and plants was done by Catarina Rydin of Stockholm University in Sweden. They again did not necessarily find that the phase of the moon affected the plant as a whole but rather just certain portions. In this particular instance, they were studying a rare plant called Ephedra foeminea. The conclusion of the scientific study was that the pollination was governed by the full moon. 

Catarina also made a statement saying “Unfortunately, scientific work on lunisolar impact on biological systems has sometimes been almost ridiculed, and the field has probably been hampered by unjustified skepticism,” she says. “Therefore, well-conducted and interesting papers like this are very important.”

These two studies are great examples of how the scientific method works. Over time we are realizing that there is a potential for the moon cycle to affect our plants. How this currently affects our seed starting is yet to be determined.

So can I say that the moon phases definitely have an effect on your germination? Unfortunately no. But what I can say is that if you are noticing better results when you plant via the moon phase then you should continue. Part of being a gardener is performing our own anecdotal experiments. More often than not what works for you may not work for someone else and that’s OK.

Feel free to reach out to me on Instagram or Facebook to let me know what your experience is with moon phase planting. Or simply leave a comment below to help out other gardeners interested in the concept.

Moon phase planting
Moon phase planting