GMSgrowsanswered grow question 3 years ago Your ph is low for a soil grow. Better nutrient uptake at 6.3 or 6.5 for soil. If you have a ph ec reader, check your runoff water for proper ph and ec levels. This is a routine for me after every water/feed. Tells me if they need higher or lower ph and also if I need to increase feed, or just water the next go round. This is doctoring 101 for cannabis. Things go out of whack in the root zone, then follows in the leaf zone. Cheers.