Drive by. My first thought was calcium. But then I have that problem every year, with my water source. Why I go heavy with slow release bone meal and alot of it, double at least what they suggest. Also, makes for a fine microbial media. And you'll always have a steady supply of calcium, plus you can't add too much for things like lockouts or toxicity. But it looks like K. Least them pics did. Stems or petioles might turn purple? and they tend to get leggy? The larger leaves turn necrotic and die? As said, wood ash, kelp extracts, and a good bloom fertilizer should fix it I'd hope. Sounds like she getting a good long douce, pardon my French. You could always add a drop or two of superthrive to your waterings. Kind of like a multivitamin for your plant. These the girl's outdoors? I seen ya talking GH Flora. Great product in my eyes. I'd hit it with some tailored to a K defisencie Maybe even a drop of koolbloom if you got some. I use the powered stuff with the flora stuff when my outdoor girls kick off. GL and Keepem Green