It is an excellent product for this purpose and specifically recommended by the vendor for this usage. Even better is the 3/8 minus composted Soil Pep.

Thank you gg48 (I hope I can call you that)!! I’m trying to put together a good mix for container grown citrus, and soil pep is the only thing I can find in my area of Colorado. If you make your own mix using it, do you mind sharing your recipe?

If you are referring to the 5-1-1 mix, I'm not sure if it would be "too fine" to use as the pine bark fines. In other words, it may break down too quickly. You may want to ask in the container garden forum about using it specifically for the 5-1-1. Last year, I made 5-1-1 but I used the smallest of the bark mulch called "mini nuggets". I have noticed though that different brands have different definitions of "mini" though. I used these: http://www.mountainwestbark.com/products/pathway-bark-or-mini-nugget/

I do note on the mountain west website, under the soil pep, it does say "fines".

I do think soil pep is a great product . I have used it as a mulch for years. I like how fine it is that it sort of breaks down right into the soil rather than sit on top for years. I just reapply each year.

I don't use that product specifically but something quite similar. And I use the standard 5-1-1 mix recipe for ALL my container plantings:

5 parts composted pine bark fines (3/8" is ideal)

1 part peat

1 part perlite

dolomite lime (1-2 Tbs per gallon of mix)

CRF if desired

Thanks to all!