Confused about soil for figs in pots
I've read over some older post about the proper soil mix for potted figs and I'm a bit confused. Some posts by Al (user name: tapla) say the soil should be equal parts:
1/8 - 1/4 pine or fir bark
Screened Turface (high-fired clay - almost a ceramic)
Crushed granite poultry grit in grower size or #2 cherry stone
This confuses me as it's 2/3s rock (essentially) and 1/3 bark and no actual soil. Do all the nutrients for the plant come from liquid fertilizer?
If that's the case, is there a soil mixture that relies on the "dirt" for nutrients? My specific problem is that my figs (which will be in pots for at least a year and some will be permanently) will be growing about 90 minutes from where I live during the week. I was going to put them on a timed drip irrigation system but now I'm concerned about fertilization.
What am I missing here?
Can make a close approximation of a good soil with composted manure, pearlite, and vermiculate?