If you have a lot of burnt tips it's a clear give-away of too much nutrients. And that can happen easily with Miracle Gro. Then the plants lock up and can't take food from the soil. Do you use a soil ph meter? I use both types of ph meters. I don't like it if the soil gets too alkaline. I think it affects the taste and quality. Not just the health of the plant. If you're using tap water know that it can variate. My tap water ph has changed in the past. It can suddenly jump in alkalinity. And I noticed when reading my water report that my water's nitrate value is currently SIX TIMES the national average because of agricultural run-off. Don't throw out your water report when it comes in the mail! I let it get air so some of the chlorine percolates out of it and that chlorine represents a salt value. Remember that it is always best to under-fertilize rather than over-fertilize because it can be hard to fix the latter. It slows them down even if a flush is successful. You should upgrade your nutrients. I've always said anyone can grow marijuana but not everyone can grow it really well. People that want to excel at the hobby spend more money than $9 on a jar of crystal. Don't get me wrong-I grew some kick-ass plants with Miracle-Gro (both the bloom and regular) like 10 years ago. But guess what? I screwed up eventually and ended up with leaves that look exactly like yours. Only worse. I locked them up. Didn't kill them, but the yield suffered. And then there is the taste factor. Miracle-Gro is just nasty all-around. I use
Fox Farm Trio,
Cal-Mag Plus (two applications early in grow), and
Neem Oil. And I'm not heavy on the water. I water a little every day rather than completely drench them. I just watered my plants an hour ago and they got about a quart each and that's it. I highly recommend using the
Neem Oil immediately on your grow. I urge all growers to use it. It is an awesome product that stops fungus in its tracks. And even keeps spider mites from laying their eggs. Even helps prevent some pests in the soil if you use it that way (I don't). I use plant-based organic dish detergent as an emulsifier. Neem even has a slight nutrient value. I just sprayed some on my new seedlings and they're only three inches tall. Neem will prevent tragedy. I haven't had a single problem of any type in years since I started using it. And I had frequent problems.
Fox Farm is excellent and I Iike the organic nature of Big Bloom. It's just earthworm castings and bat guano. Near the end of the project I taper back the Tiger Bloom and up the amount of Big Bloom and I swear it gives a better taste to the end product. Sweeter and less harsh. Makes the Blue Cheese really taste cheesey in my Starry Vape.