Calcium Deficiencies Appear on New or Actively Growing Leaves Calcium deficiencies tend to appear on newer or growing leaves, which means calcium deficiencies first appear on leaves where there’s rapid vegetative growth. Some of the most noticeable signs of a calcium deficiency will appear on newer or growing leaves which may display: Dead spots Crinkling Spotting / Mottling Small brown spots Stunted growth Small or distorted new leaves Curled tips Leaf die-off Affected leaves may appear green besides the spots. If you’re looking for a way to supplement calcium in your organic or soil setup, I highly recommend a product called “Dolomite Lime.” Dolomite is a good source of calcium and magnesium and can be mixed with your soil. The great thing about dolomite is it works slowly over the course of a few months. Dolomite has a neutral pH of about 7.0 and will help keep soil at the correct neutral pH range which is optimum for cannabis growth.

Hey Beast. I would say you accidentally spilled or sprayed something on them that was too strong for the leaves to handle, such as a strong nutrient solution or bleach etc. The reason being that it is all in one location and in a spray pattern. Perhaps the plant was facing the other way and a bird landed in the pool and splashed it with chlorinated water?