hmm doesn't look like calcium to me, looks a lot simpler than that. check out International Cannagraphic Magazine Forums - The Complete guide to Sick Plants,pH, and Pest troubles!

this is a very useful resource for almost ANY plant problem. Scroll thru til you see a pic like yours.
dutch.lover Reviewed by dutch.lover on . yellowing tips, brown spots, Ca deficiency? Hi, first time grower, 6 plants, bagseeds, day 23 of veg. 2 of the plants have nasty looking yellow tips on the lower leaves. Pictures say more than words. I water, but have not as of yet fertilized. I just got my fox farms products today and will be using them tomorrow. Soil is too wet to water today. 2 175w MH, 6 or so 100w cfl's for lighting. Temp is always around 78-80. Low humidity <20%. Was thinking about putting a pot of water in there to evaporate off some moisture. Three of Rating: 5