Looks like calcium deficiencies Calcium deficiencies are more likely to appear when… Grower is using filtered or reverse osmisis (RO) water to feed plants – the amount of calcium found in tap water varies, but some tap water has enough calcium to prevent calcium deficiencies PH is Too Low – If grow medium is acidic (below 6.2 pH, Calcium can get locked out even if the Calcium is physically there) Growing cannabis in hydroponics or coco coir without supplementing extra Calcium (it’s recommended to use a Calcium supplement in hydro or coco) When growing in soil that hasn’t been supplemented with calcium (usually from dolomite lime) Too much potassium can also sometimes cause the appearance of a calcium deficiency Outdoors – calcium deficiency is more likely to appear in acidic soil (below 6.2 pH)