The question is about the size, ratio and composition of the drainage and soil layers in some improvised terrarium. It's made out of a 8'' (20cm) truncated/shaved off glass sphere (basically a cookie/candy jar); accessories include some colorful fish tank gravel, activated coal, a nylon bag, some potting and dark soil, as well as a couple of small random plants...
I read that:
- Maintaining the soil moisture is difficult even with an adequate drainage layer.
- It's theoretically possible to restrict root growth; a smaller area to grow roots in means less soil to grow in I would imagine.
- How deep the root zone is varies from plant to plant.
- Coal is only a must in you have a closed up terrarium.
I've seen different types of layering, proportions, even mixing the coal with the gravel or even with the soil in some instances... is it just about aesthetics?
- Is there an ideal drainage to soil layer ratio in a terrarium; is it 1:1?
- How would you setup the layers here, in particular the soil layer, so as to restrict root growth and ultimately constrain growth to the jar; 1 inch per?
- In terms of composition, how much coal does one use and is it layered above or below the gravel, or would you mix it in any other way; does it matter where it is and can it be detrimental in some cases?
- Do you see any issues with having the soil layer made out of different types of mix (such as potting and this dark mix) side by side?