I've never used dry amendments, but I think you'll be fine ...the aerated SIPs I grow in are about ~15% smaller capacity than that and grow 1/4lbrs+ while trying to keep them smaller; in Lush, but I don't think the soil is that different :though this time I filled the EBJr’s with straight Roots Organic Original, zero amendments and started with soil full mounded so I can’t add dry amendments later.
"ROOTS ORGANICS
LUSH
DERIVED FROM
Earthworm castings, dolomite, limestone, phosphate rock, bat guano, langbeinite, feather meal, sulfate of potash, fishbone meal, soybean meal, fish meal, kieserite, volcanic rock dust, blood meal, crab meal, alfalfa meal, greensand, volcanic ash, kelp meal, nettle leaf and hop flowers
*0.8% Slow Release Nitrogen from feather meal, blood meal, bat guano, soybean meal, alfalfa meal, fish meal, fishbone meal, crab meal, nettle leaf, hop flowers.
CONTAINS NONPLANT FOOD INGREDIENTS
1.5% Humic Acids from Leonardite and Peat Moss
0.1% Beneficial Bacteria and Mycorrhizal Fungi *
*BACTERIA CONTENT
Bacillus subtilis
2,000,000.0 CFU PER GRAM
Bacillus licheniformis
1,000,000.0 CFU PER GRAM
Bacillus megaterium
1,000,000.0 CFU PER GRAM
Bacillus simplex
1,000,000.0 CFU PER GRAM
*MYCORRHIZAL FUNGI CONTENT
Rhizophagus intraradices
0.4 PROPAGULES PER GRAM
Funneliformis mosseae
0.03 PROPAGULES PER GRAM
Septoglomus deserticola
0.03 PROPAGULES PER GRAM
Soil Amending Ingredients: Peat moss, earthworm castings, pumice, perlite, and coco fiber."