I did not find any information on the web about this.

I am currently thinking about protecting the soil of several pots on my west Germany southside balcony before the sun and any kind of stranger plant or vermins with a layer of low-nutrient soil, and topping it with a layer of Stone or Granite.

The idea roots back to an earlier idea in spring, when I used this technique to maximize solar radiation on my Tomato and Chili freshmen (this idea itself is based on my Computer Graphics / Illumination interest).

I am just beginning with my adventures in gardening, so experience with this experimentation is pretty low, and I wonder if anyone has tried this out, too.

What I've found out is that you can pour faster, as the mass of the stones will decelerate and spread the falling water enough, such that it does not nuzzle up the soil so much anymore. But this question is more about the protection part of it.

  • Btw, please pardon any strange gardening parlance by me. I am a german programmer from Stack Overflow normally :P
    – phresnel
    Jul 30, 2014 at 20:09

2 Answers 2


I don't see that the layer of low nutrient soil will help much, but crushed rock can be beneficial. I have used them in a 3" layer on larger pots, with good results. The biggest problem with it is repotting, but that is only a minor nuisance.

I've found the same thing regarding watering. Rocks also keep the plants cleaner, by minimizing soil splashing.

  • Plus water moisture condenses out on the cool underside of the rock mulch helping economize on water usage. Jul 30, 2014 at 21:07
  • The idea behind the low nutrient soil was to minimize, argh language, the opportunity for unwanted plants and organism, incl. sorts of fungi, to find something they can feed well on. But then, it probably just makes them root faster (which seems to be the sole point behind low nutrient soil). Hmm, maybe a no-nutrient soil like volcano ash or sand could increase the effect?
    – phresnel
    Jul 30, 2014 at 21:39
  • 2
    Weeds will grow in anything. You cannot control them with the kind of soil. Only by minimizing the number of windborne seeds can you reduce the number of weeds.
    – kevinskio
    Jul 31, 2014 at 0:44

Another programmer/gardener here. :)

I've heard what you're describing referred to as "non-organic mulch." It doesn't decompose and enrich the soil the way organic mulch would, but that also means it's lower maintenance. Like organic mulch, it can help retain soil moisture and reduce wind-blown dust. It also helps keep small animals from digging in container plants.

  • What I find regarding organic mulch is that it generally doesn't improve the potting mix much anyway, especially since most plants should be repotted regularly. I rarely use organic mulch other than unmilled peat moss, or sometimes spanish moss, in pots.
    – J. Musser
    Jul 31, 2014 at 3:30
  • 1
    True, potting mix is already pretty rich. I save my organic mulch for gardens and landscape basins. Where I live, the organic content of the native soil is almost nil, so even a small amendment is valuable. Jul 31, 2014 at 4:12

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