I've never used the cubes myself but I can see a problem with stacking them as that would make them top heavy, and yu would have to support them some way. Plus the roots would be coming out the sides as well as the bottoms. There is a rockwool slab that yu can get to place under it that will allow the roots to grow into a wider bottom and spread out. This will weld the block to the slab and make them much more stable. I've seen a lot of people in the smokers' magazines use them with great results. If I used that medium, that is what I would do. Either that or a specialized container with hydroton surrounding the cube but with enough holes in the bottom for the flood to get into it...It depends on if yu are wanting to grow large plants or smaller plants. All of the RWcubes in F&D that I have seen in the mags, the people were growing relatively small plants that were harvested in a shorter flower phase. I think that is because the roots don't grow as prolific as in the containerized mediums and therefore the plants don't grow as big, but finish sooner than the more "naturally" grown plants. Everyone that I have seen growing larger plants grow in some level of container that allows the root system to get much larger which allows the plant canopy to get larger. I hope this helps. green grow mojo