How lunar cycles affect plant chemistry and what that means for cultivators of cannabis.
A full moon casts zig-zagged shadows across your bedroom floor. They wave black shapes up your wall and tickle your closet door. Inside, your cannabis grow rests along with you. Then, a loud bang from inside your closet. You wake up. Another bang. Then another. Something’s moving in there. A low growl resonates from your closet. Your passion for fairy tale tropes tells you exactly what you’re dealing with before it bursts out! A were-sativa like something out of Day of the Triffids?
No, a full moon doesn’t change cannabis into a monster. However, some claim that lunar cycles play a role in cannabis cultivation. Let’s take a look at how those cycles might impact a cannabis grow and what it might mean for you.
In 2012, the journal The Annals of Botany published an article that noted there is some evidence that suggests lunar cycles play a role in plant development.  In fact, they specifically noted that “there may be continuous modulation of root elongation growth by the lunisolar tidal force.” However, the researchers also indicated that “the evidence for a lunar or a lunisolar influence on root growth or, indeed, on any other plant system, is correlative, and therefore circumstantial.”
Interestingly, however, the researchers also pointed out that much of plant development occurs at the protoplasmic level—a liquid environment. Given that the moon’s most noticeable effect on earth is the ocean tides, it’s entirely possible that the lunar cycle could play a role in how plants develop.
In 2016, a group of researchers published their findings on lunar cycles and how they impact certain plants in the journal Ancient Sciences of Life.  They supported the idea that lunar cycles could play a role in plant development. Tavhare et al said that ayurvedic wisdom has long indicated that certain plants should be harvested during lunar stages to maximize their benefits for humans and that “the logic behind such recommendations is being validated by modern scientific research.” The researchers noted that the plants they were studying produced more of their vital compounds when harvested during certain times, which corresponded to changes in the lunar cycle.
Does this mean that harvesting cannabis during a full moon is going to improve its potency?
Perhaps. Some sources, outside of the scientific literature, seem to think so. An article in Cannabis Now, for example, discusses using of the synodic cycle of the moon as a guide for increasing the vivacity of cannabis plants. The first phase is said to be good for planting seeds and taking cuttings; the third phase is said to present the highest moisture content; and during the fourth, waning phase, energy is said to be pulled into the roots, presenting an opportune time for maintenance.
- Barlow, P. and Fisahn, J. “Lunisolar tidal force and the growth of plant roots, and some other of its effects on plant movements.” Annals of Botany. 2012. vol. 110.2:301-18. [Times cited = 43; Journal Impact Factor: 4.401]
- Tavhare, S. et al. “Effect of seasonal variations on the phytoconstituents of Aśvagandhā w.r. to lunar cycles.” Ancient Science of Life. 2016. vol. 35.3:150-8. [Times cited = 2; Journal Impact Factor: N/A]