im not experianced in soil growing but im sure ive heard ppl sayin ph the water b4 u feed ur plants.. i use hydro so cant give exact advice on this.. also when you water collect some ov the run off from the pot n check the ph.. this way you get an idea of ph in soil..
ph for soil shud be in the range of 6-6.5 i believe.
you could just get a tester frm wallmart ,, either a soil tester or water tester.. might be better with a water tester so you can check the ph b4 you add it to the soil..
you can buy ph up and down , it dont cost that much for 250ml bottles.
i dont know if ive been any help m8 but im sure some1 will pop in n help you out but ide check the info ive given you b4 you go ahead coz im a hydro grower n neva used soil.
good luck.