Are these in containers or in a garden plot? If in a container there would be no really good reason to add garden soil since that tends to inhibit drainage in containers. If in a garden plot your soil is there and you need not be concerned about it. All the microorganisms you will need should be in the compost, unless it was sterilized before being packaged in which case it isn't worth anything.
The nutrients in the Rock Phosphate and Greensand will not be available to plants this year since it takes those soil microorganisms several months to work on them and release those nutrients. If this is a container mix there was no good reason to add that material to the mix.

Kimmsr, thanks for your reply. It is a container garden (a box we built and large pots) not a garden plot. I think his reasoning on adding soil was to get the microorganisms to break down the mixture. He said he used the Rock Phosphate and Greensand with everything he planted so recommends it.

I looked up the Back to Nature and Nature's Blend it doesn't appear it is sterilized, has anyone else used this and know?

Susan

Like Kimmsr said, no good reason to add soil. The compost is already full of beneficial microorganisms. Unless you have really good soil there would be no benefit.

Good, I'll leave it alone then.

Thanks, Susan

Since you really don't know the nature of the compost and the micro-organism population, you could top dress the containers with soil. This way, with watering, there should be some movement of these organisms into the rest of the container.

Some plants like tomatoes will be OK with soil covering the stems, be careful not to add too much near the plant stems of the other plants.

It sounds as though the mix will be highly water retentive. You may wish to investigate removal of water via wicking it away as a back-up plan. Alternately, you may wish to consider adding a substantial amount of pine bark and a small fraction of perlite to the mix to improve aeration and reduce water retention.

You should probably consider adding lime (dolomitic) to the soil as well - especially if the RP is primarily coarse (larger than 80 mesh), or something with additional Mg in it (or add MgSO4 [Epsom salts] occasionally in your fertilizer solution - or by itself in solution).

Al

You guys are way ahead of me in all this. I'm not following the lingo, sorry.

What is wicking and what is RP? Isn't it good if the soil is highly water retentive or maybe it's too much of a good thing. I like the idea of adding soil at the top, I think I understand the logic in doing that (that the microorgs would get into the soil over time through watering). Anyway, I appreciate everyones feedback and help.Thanks.

RP = rock phosphate

Follow the link at the bottom to learn more about container soils/wicking.

There is a happy medium between the amount of air and water soils should hold. One is just as important as the other. Some soils are too water-retentive to be healthy for plants. By the ingredients list, I suspect yours is one of those that will be too water-retentive. Soils that are well-aerated and need more frequent watering are much easier to grow in. The trade-off though, is that you'll need to water a little more frequently.

Here is a link that might be useful: I'll take you to lots more info if you click me.

Thanks Tapla, I'll read the info in the link.