I am getting irregular PH readings in my Garden .I have potatoes sown already and the reading is between 4 and 6 .Where I have my cabbage,it is reading 6 .However other areas are only ready 3 .I evenly fertised two weeks before sowing .I fertilised with 10-10 -20 .Could that be the problem I wonder.Will anything grow in 3 PH .New to gardening as I am sure you picked up already .A closed down Publican trying to stay sane lol.Thanks in advance .