Clint you can space them however you want, most people put them in close so they are full and nice right off the bat, but it doesn't have to be that way, mostly they just need really good drainage, so these systems that are available are a good idea because they've been tested. Yet they can be expensive, which is why I decided metal frame...so mine is the metal shelving that you see in bakeries, I had 2 shelves that somehow randomly showed up at my building, and they were shelves with bricks for a couple of years, but now I've confiscated them and will turn them into mini walls. Again, I'll know more this summer. I'm hoping that if they start getting crowded out, I can pick some off and make more room, I don't think they'll die so suddenly that I wouldn't notice...there are others who have done this who may know more though.
