Mushroom compost is great. It is produced by mushroom farms as a waste product of their opperations. There are not many vegetarian organic fertilizers out there, so I think your organic options will be a bit limited. I love Osmocote, but that is a chemical fertilizer, not an organic one.
I mostly grow veggies in containers and was also told feeding them was very important. I use Gro Power Plus, as recommended by several folks at our local, family-owned nursery. It is not certified organic, but it is a technicality issue as far as I know. (I haven't investigated it myself, but have been told this by various people.) This particular fertilizer is meant for the initial growth when the plants are getting started. It has high nitrogen.<br><br>
Once the plant is established, then I have been advised to switch to a fruit-enhancing fertilizer. I have Dr. Earth's azalea fertilizer for my blueberry bush, but haven't gotten to that point for the other produce...yet.