I like the way you thought about this, it may be arbitrary, but it certainly gives you an idea of what a mix will be like before making it. Have you seen my well aerated soil formulas post? I think that taking this method and applying the method of using (ad/ab)sorbent materials to achieve diferent mediums, would be useful for tailoring mediums for specific needs.

Although I still use 5-1-1 for many plants,I want to take a moment to talk about why I wasn’t entirely satisfied with the results from my 5-1-1, especially my figs, and decided to change many of my plants into coconut husk, and then later making me decide to grow some plants side by side to see if I made the right decision. Last year in January I began a thread to ask about advice onto what soil mix I should use to pot a variety of plants, specifically figs, blueberries, a bay tree and a dwarf nectarine. You can read through here if you are interested; http://forums2.gardenweb.com/forums/load/contain/msg0120561912795.html?72 28 days later I came back with a follow-up on how the plants were going since they were re-potted into 5-1-1, and in most cases no plants were doing particularly well! This thread is here; http://forums2.gardenweb.com/forums/load/contain/msg0301115119857.html Because of this, when many of my plants went dormant in winter I potted them into a new mix, in larger pots using the coconut husk chips. After bud break all my plants took off in their new mix. Unfortunately I dont know if this would have happened anyway, had they remained in 5-1-1. Perhaps their growth now is because they have not been disturbed after bud break. Perhaps it was too hot last year. Perhaps there is another cause. Either way, take for example two of my original figs- White Adriatic and Black Genoa. In the 4 months from Feb to May and up until the first frosts, many of my plants did nothing, or put off a single leaf or two. Now, in just over 3 months since they woke from dormancy, in coconut husk chips all my figs (and my other plants in husk) are doing amazingly. 2nd Feb 2013 White Adriatic planted into 5-1-1 19 March 2013 - 6 Weeks Later 5 April White Adriatic - small amount of growth 23 September - Breaking bud in coconut husk chips 9 October - Less than a month later 22 November - About 6 weeks after breaking bud Now Black Genoa Feb April October after being put into coconut husk while dormant Today

californian you are missing the point of the experiment.. which is to germinate (or not) seeds from the get-go in a pre-mixed soil medium. The experiment shows strong fertilizers in the soil are not conducive to germination. It's a multi-tiered experiment that also is looking at the growth patterns for what does germinate. We're not trying to show the effect of fertilizer AFTER the seeds are germinated, but the effect BEFORE the seeds germinate and then closely watch the results. The fish fertilizer is 5-1-1 and nothing has germinated to date. Instead we got all that mold growth. The other aspect of this experiment is for observation notation in the project. I know what you are saying, but that's not the premise for this particular experiment. We could try reducing the amount of fish fertilizer and 10-10-10 used to see what amount allows germination and then note what kind of growth we see.

Mixes like Fafard #2 (vermiculite, perlite, and peat moss) are used by lots of professionals because it gives the seeds the right conditions for germination. This mix really doesn't have any nutrition to speak of, but the seeds themselves provide nutrition to the plant for awhile. So, seed starting mixes aren't really soil, but they are good for starting seed. You get a high percentage of germination. You have to transplant the plant to real soil within a month or two, or it will get sick from lack of nutients. "Potting soil" really isn't soil from a soil science perspective, though it may have some nutrition. Soil is the mineral stuff in the earth's horizon. I used to be skeptical about seed starting mix, but I'm sold on Fafard. I buy just one bag a year, because it goes a long way.