gettingreen...I wonder if the ph in your pots takes a wild swing down when you water....there may be too much rotting peat in the soil....causes acidity and low ph....
I used some Oak ashes from a wood heater to sweeten my soil,but until the peat composts ,it will cause swings that lock out the nutes.
I used some Oak ashes from a wood heater to sweeten my soil,but until the peat composts ,it will cause swings that lock out the nutes.