If there is a coarse layer below a fine layer, there will be no capillary action to draw water out of the fine medium. However this can work to advantage, depending on the plant, and the conditions where it is being grown. For example; in hot arid conditions, a layer of crocks will prevent the water in the finer compost above from leaching out, (except for that pushed through by the 'head' of water). This may mean that the plant is effectively kept moist for a little longer, and the surplus will evaporate before any harm is done. I regularly plant certain bulbs surrounded by stones, to prevent wet compost around the bulb. However, but this is not a sandwich layer across the pot. In this scenario the stones are all the way to the top of the pot, with no fine material in them. The important thing is to understand all this before experimenting! Planting some bulbs on a layer of gritty sand is very good for finding them at the next repotting. Normally for my purposes, and in my climate, I want maximum capillary action through my pots and into the surrounding sand. Peter (UK) On 23 January 2015 at 16:32, Alberto <ezeizabotgard@hotmail.com> wrote: > And even better if you mix all coarse materials and put no fines at all. > >