PLEASE HELP!!! Can't diagnose as necrosis spreads on leaves

Something is wrong with my only plant and I am having trouble diagnosing it. The problem started with the larger lower leaves and is working it's way up. Only the larger leaves seem to be affected. The affected area starts at the center of the leaves, around the veins, and makes its way outward. I tested my ph and it seems to be around 6.5-7.0. Bagseed. Problem first appeared two days ago but seems to be spreading rapidly. I've read alot about deficiencies but still can't figure this one out. Is it P? Or Mg? Please help me out it's my only plant and I've been growing her for a good six weeks already.

you need to give up a bit more info about your grow. type of grow, environment temps, ppm's, lights... ALL DAT! then i will probably be able to put ya right where ya need to be.

my bad. it's my first real grow. It's bag seed in a one gallon pot with mircale grow moisture control soil. I keep it in two 22 qt styrofoam coolers. it has been under 4 23 watt 6500k 1600 lumen cfl bulbs, running on an 18/6 schedule. It's vegged for about six weeks. i did minor training, bending it side ways for hight. i fertilize with miracle grow all purpose plant food. it's 21-14-? can't remember the k right now. temps stay around 70-75. recently though, they've dipped because i keep my windows open and it's getting cold outside. box has stayed around 66-70 now. yesterday i switched to 12/12, changing three of the bulbs out for 2700k bulbs. should i not have done this, and can i go back to veg. today i foliar fed it a high p nute because it kinda matches p def. symptoms. i also checked the ph of the soil and it seems to be between 6.5-7. i used a soil ph tester kit that uses powder from capsules mixed with the soil and some water. i got the water from my water jug that holds the water i use to water my plant, figuring that'd be a fair judge of the ph of the soil after watering.

nutrient deficiencies are always hard to diagnose.

i'm pretty sure that is calcium though. can you tell me what is in your nutrients?


when looking up deficiencies using google, avoid images of MJ plants. often people will post images and declare it as this or that when it just isn't.

take a look at this:

http://blog.fluidsensoronline.com/2010/01/calcium-deficiency-in-plants/

It's the dirt! Miracle Gro just don't
work for weed plants. Look into getting
another grow medium. Like Fox Farm
Ocean Forest or sunshine mix 4 or even
hydro. Your plant is only going to get
worse!

not true... there are many growers that grow just fine in miracle grow.

When I get home tonight I'll look at the package and can tell you the exact make up of the nutrients. I wasn't putting much stock in the pic search because I noticed identicAl pic results for different searches. But I was reading a lot of detailed info on each def and trying to diagnose that way thanks for the help skunk