Hopefully someone experienced can shed light. Using Advanced Nutrients, fed them a couple days ago with a light feeding (flowering week 1). Other 3 of the same genetics are doing fine with the nutes, no burn and no curling. Then there is this one: New growth is curling up a bit but tips aren't burnt. It's either reducing nutes or feeding some water w/epsom salts. Thanks.
Is this pot's PH the same as the rest? It looks like the back left plant in pic #2 is sum what affected to? Due u test the PH of your runoff water
Yeah, test/balance out your Ph before you try anything. Mg is best absorbed around 6.5-7Ph, just like most other nutrients, so 6.8 is a good number to have. After that, if your numbers are okay, I'd say it's a magnesium deficiency. That causes those leaf tips to curl up like that, resembling a taco or something. Check the numbers on your fertilizer, as Mg can get locked out by having too much P, K or Ca, and, of course, by an out of whack Ph level. Epsom salt can help, either as foliar feed or in the water. Usu dose is 1tsp/1gallon. Or, better yet, get a product called CalMag - I think that's the name. Do a search here for it. Also, go here: Ganja Guerrilla's Hall of Marijuana Plant Abuse to find an awesome gallery of deficiency pictures. Some of the ones under "magnesium deficiency" look exactly like your lil gal. Good luck!