I know that the experts on this site suggest 7.0 pH for your soil, but the experts at Advanced Nutrients Medical say that 6.3 pH for soil is better, because the slight acidity of the grow medium causes the plant to absorb nutrients better.

I agree with the other comments. Looking at your pictures I’d say your plants are suffering from nute burn. What are you feeding them, anyway? It’s not just the fertilizer but the parts per million in your watering can that matters. If the ppm is too high, your leaves will turn yellow at the tip and around the sides.

Flush them with pure water and start fresh. I would advise you to visit the Advanced Nutrients Medical website, in order to learn some things about plant nutrition. They have in depth articles, as well as real life technical help on the other end of a toll-free line.

I would also urge you to get some better lighting, if you want your plants to grow tall and potent. Fluorescents just don’t cut it. Even a single 400W Metal Halide or High Pressure Sodium light would do wonders for your gardening efforts.

As far as nutrients, I’m using Sensi Grow A & B and Sensi Bloom A & B, which were developed by plant scientists specifically with cannabis in mind. Miracle Grow was developed with vegetables and flowers in mind, definitely not cannabis.

These species specific ferts have all the macro and micro nutrients that your pot plants will need. I also use root colonizers, in order to enhance root growth and food absorption. Have you heard the expression “as below, so above?” If you got healthy roots, you’re gonna get a healthy, bushy plant with major sized buds.

Speaking of increasing bud size, why not consider using Bud Blood, Big Bud, and Overdrive during specific weeks of the flowering stage? Bud Blood is meant to be used during week 1 only, while Big Bud should be mixed in to your nutrient solution during weeks 2, 3, and 4 of flowering. Then during weeks 5 and 6 it’s Overdrive’s turn.

These very powerful bloom enhancers should never be mixed in all at the same time. They would burn your cannabis plants to a crisp, if you did that!

I also believe in feeding my medpot plants (my wife Claire and I are medpot patients) Vitamins in the form of two excellent Advanced Nutrients products: B-52 and Grandma Enggy’s Seaweed Extract. The latter is like a multi-vitamin, while the former is an excellent B-complex.

If you know your vitamins, you know that humans take a B-complex to reduce stress. I give it to my marijuana plants for much the same reason.