critique my potting mix recipe (for sub-irrigated planter)
hello and happy gardening to all.
i've done my homework (though, as a gardening amateur, my understanding is likely far more limited than yours) and purchased all the raw ingredients necessary to make a well-draining but moisture-wicking potting mix suitable for a sub irrigated (a.k.a. self-watering) earthbox-type container garden. i'll be mixing en masse (i see myself in knee-pads on a tarp in the near future) to the tune of a cubic yard or so. the time for fall planting is fast approaching in my area, and before i screw up several cubic feet of mix, i wanted to get some critique on the best ratios of ingredients either based on your own experience or simply by your educated opinion.
i have the following in my stockpile:
12 cu ft sphagnum peat moss
12 cu ft pine bark fines
8 cu ft coarse perlite
4 cu ft coarse vermiculite
other amendments and fertilizers:
5 lb worm castings
5 lb dolomite lime
12 oz mycorrhizal fungi
20 lb garden-tone granular fertilizer 3-4-4
1 gal liquid fish blend 2-3-2 (for supplemental feeding as necessary)
NOW here's where i need the most help. i was thinking the best balance of moisture retention, proper drainage, and reasonable cost would be a formula similar to the following:
40% sphagnum peat moss
25% pine bark fines
25% coarse perlite
10% coarse vermiculite
plus incidentals (lime for ph, some castings for good measure, etc.)
what do you think? am i cheaping out by not including enough vermiculite (it is quite pricy here)? or, conversely, do you think i could get away with increasing the peat moss or bark fines to bulk up the mix (as those are the cheapest ingredients and in plentiful supply)?
PLEASE HELP!!! i only get one chance to make this right before i'm stuck with it the whole season.