Alright guys, I'm new to the whole bonsai thing. and by "new" I mean I haven't planted any yet but I ordered seeds (madagascar baobab, chinese elm, and umbrella tree) which should come in sometime in the next few days. That being said, I'm looking for a good soil mixture so I can plant them when they come in. I live in an apartment and my porch is pretty freakin shady most of the time so my only option really is indoors with fluorescent lights.
In my reading I'm finding that there are three main types of materials to mix to make soil: inorganic porous, inorganic non-porous, and organic. I know there are a lot of fora on this subject but I haven't been able to find an answer to this particular question.
Is there any reason for me to not use just sand (inorganic non-porous) and some sort of bark (organic)?? I feel like the bark will give the water-retention aspects of the soil that the inorganic non-porous material would normally bring and the sang will provide the fast draining ability...
But, like I said, I'm a total noob so please tell me whether or not I'm correct in these assumptions...