Cilantro growth problem
Im having this tip burn type problem with my green-house grown cilantro. Variety is slow-bolt. My c.f is at 1.6 , ph 6.3-6.5, A light fan is running over the plants to aid in transpiration and help get calcium to the leaf tips, and I'm using a herb nutrient formula customised to my water. Also have shade cloth over the area to keep the temperature down. The problem is starting in the new growth. Any ideas? Cant think what else to do.