I do not do a lot of propagating fig's and i do not pot a lot of fig's. For one thing,for me it is the easeast fruit tree to multiply and that is the scary part.The ones that i pot are the most tender ones but also the most delish.
The way i grow my potted figtree's for the summer is, i drill 1/2 or 3/4 inch holes close to the bottom.
Dig a hole in the ground the size of the container and about 2 or 3 inches deep, set the pot in the hole, fill dirt back in.
I use a thin layer of hardwood leaves, than lay a layer of pine bark mulch to hold the leaves down.
I do not worry too much about the container mix, i use pine bark just as it comes in the bag and add a similiar amount of Turface. This combo is mearly to survive my tree's during the winter period.
Roots will quickly come out the bottom holes and by the end of fall the roots will be about 4 feet long or longer.
Fertilizing is even easier only twice,April then in June with tripple 10, no fancy stuff, less watering and most of all no worrying.