Which deficiency is this?

[stinkbudd]

My plant has been slowly turning yellow, starting from the lower leaves and working its way up the plant. I thought it might be nitrogen deficiency but then I noticed something else. When the leaf becomes completely yellow, it then begins to change to a different color - a light purple color (not a dark purple), then it dies. So I am guessing a molbdenum or a phosphorus deficiency. Any thoughts?

[Pass That Shit]

I think you will need to tell us what you are growing them in? What have you been feeding them? And how frequent and how much water you have been giving them?

[stinkbudd]

This plant is growing in organic soil....very good soil. The Ph is 6.9. I have been feeding it pure blend pro grow for vegetative growth every two weeks. The soil is moist. Not wet and not dry. The tips of the leaves are burnt and curling just a little bit upwards. The top of the plant is nice and green. Can nitrogen deficiency cause the yellow leaves to turn a light purple?

[Pass That Shit]

What is the pH in the water? If your soil is 6.9 and your irrigation water also has a high pH, you may need to lower it a bit. It sounds like you're overfeeding them as well, but if you post a pic, we can tell better.