FWIW A little experiment I ran a few years ago I planted some bolivian rainbows in 3 gal pots. 1 plant was in Azealea soil pH 6.2 1 plant in Premier Pro Mix MBX with a little composted cow flop, pH 6.8 1 plant in Cactus soil, pH about 7.2 The plant in 6.8 pH soil produced over 2x as many pods as the other 2 combined had 0 insect or disease problems. In the garden, a pH of 6.5 to 7.0 has done the best for me. Just My Experience L.B.