I already bought the E.B. Stone Edna Organic Soil.
What happens if I add pine bark and perlite to it?
does this make it worst or better?
do you wash the plant/tree from the original soil it came in when using the new mix?
If you have access to appropriate size pine bark, I think you'll be very happy if you go with something like
4-5 parts of fine pine bark
1 part of the Stone soil
1 part perlite
2 tsp garden lime per gallon of soil or 1/3 cup/cu ft.
For anyone else listening in and noting the reduced amount of lime suggested, it's because there is already SOME lime in the E B Stone soil.
Whether you should bare root or not depends on the plant material we're talking about and where it is in its growth cycle, so you'd need to be more specific for more specific advice.