Tomas, What kind of bulbs are you growing? I have not had positive experience with coir, but I know a number of very good growers who love it. The problem for me is that it takes too long to dry out-- it stays too wet and soggy, even for plants that like a lot of moisture. I find peat more manageable for anything acid-loving, even considering its problems of unevenness, short life-span, rewetting difficulty, etc. Other options are composts or leaf mould, but these should be of the highest quality; don't use anything with wood pieces in it. In any event I use only a small % of organic component in most of my mixes. The mix is essentially inert: sand and pumice in varying proportion and totaling 3/4 or more of the mix overall. Dylan