Well does it? Or does it only grow on one side? Or does it grow only on the side further from the equator? Is there any truth to this old adage?

  • 4
    Not consistently enough to navigate reliably by...
    – Lost
    Oct 8, 2012 at 20:05

3 Answers 3


Moss grows best in the shade (and damp, but most relevant here is shade). Because of the curvature of the Earth, in the northern hemisphere the north side of trees is shadier than the south side, so if moss grows on only one side of a tree, it is likely to be the north side. In the southern hemisphere, the whole thing is mirrored so the moss is on the south side. This is, however, nothing more than a rule of thumb, as there are many other factors that affect moss, especially the density of foliage and humidity.

  • 2
    So if there were a bunch of trees near a pool at the bottom of a waterfall, the moss would probably grow on the side of the tree facing the waterfall because of the moisture? Oct 8, 2012 at 17:57
  • 1
    Yes, that's right. For best results you'd probably want no more than a few trees without any standing water nearby. If moss grows distinctly on one side and not the other, that's likely the north side.
    – Kevin
    Oct 8, 2012 at 18:01
  • 4
    +1 but remember, moss can grow on any side of a tree, or all sides :-)
    – Rory Alsop
    Oct 8, 2012 at 22:48
  • Or, if you are in a forest, and there isn't a significant body of water around, and every tree has moss on only one side, and they all match... that's probably North. Probably. Dec 17, 2015 at 18:07

Moss prefers damp locations irrespective of facing.

You need to cut out a few variables before you can use moss as a pretty reliable method to determine North:

  • Ignore moss on the ground. The ground is usually damp due to water evaporating.

  • Ignore moss that's growing on an incline. An incline slows water run off so the area stays damper for longer.

  • Ignore moss that's growing on rough bark/stone. Like an incline, rough bark & stone slows water run off.

With that in mind, choose moss that's growing at least waist height on a vertical, smooth surface.

It's not 100% reliable however. So check around for other mossy regions to get confirmation.


There's some truth to it in that moss prefers shady areas rather than directly sunny ones, so (in the northern hemisphere) since the north is the generally more shady part, you'd assume moss will be more likely to grow on the north of the tree.

For me though, it's nothing more than a curious fact rather than anything to reliably use in terms of orientation or navigation. There's all sorts of other variables that can cause moss to grow or not grow, and like any living organism's placement there's always an element of randomness as well! Lots of things can affect it, from humidity to moisture to the shade other objects cast around it. If you're trying to use this to navigate it could easily give you a false sense of security or make you feel uneasy about your chosen direction if the "moss rule" contradicts it.

So yes, there is some truth behind it and it's nice to know, but not reliable enough to really be of much use.

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