Hi Gang, I've started with the styrofoam peanuts--I guess I'll know in a year or two how they work. But, I hedged my bet a bit--I'm just going to try them with agaves that enjoy big pots and which are easy growers. Some of these agaves could grow upside down in a wet ditch and do well--they defy the rules if they get enough heat in summer. If things work out I'll try the peanuts with more tolerant bulbs. I wanted to replace the black lava rock (scoria) with peanuts because it is one of the more expensive components of my soil mixes. A lot of plants seem to do so well with it, and I have always supposed they do well because the scoria provides air spaces in the soil. I don't know if they have such air spaces in habitat--but the effect is helpful here. I suppose (just guessing) that the air pockets prevent anerobiosis during rainy periods. But, the styrofoam peanuts do not behave when I mix them with other soil components (coarse sand, perlite, humus, etc.) Someone on this list warned that the peanuts want to fly away. The agave mix is 2 parts scoria, 2 parts perlite, 2 parts coarse sand and 1 part humus. Due to mixing and physical properties of the components I found it easier to keep 1 part scoria and 1 part perlite--replacing them with an equal volume of peanuts. Then, because the darn peanuts wanted to fly away to the ends of the earth, I had to top dress the big pots (5-gallon or 10-gallon, etc.) with a layer of lava rock (maybe heydite would work or just pea gravel--but pea gravel is toxic for my lawn mower). So, I replaced about 30% of the lava rock with peanuts, and about 50% of the perlite (by volume). Given that the peanuts are free for me, I did realize savings, but not as much as I thought. I'll experiment for a while and appreciate all of the information that has been provided by others. Cordially, Conroe Joe about 65 F, partly sunny, no rain today