I would also ask how often you are watering? Over watering often looks like other problems and a 3 week old plant shouldn't have a nute deficiency sufficient enough to cause that much yellowing unless you are growing in some sort of soiless medium that had zero nutritional value to start with.
doco Reviewed by doco 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