Feeding too much? Too little?

[2Shady]

Greetings All,
We are newbie growers so appreciate any help or advise you can provide. We currently have 15 autoflower plants at 10 weeks of age (AK-47, Amnesia Haze, Girl Scout Cookies Extreme, Gold Leaf). They are in potting soil (Miracle Grow mixed with a bagged "garden soil"). Some are planted in plastic 3-gallon pots; some are in fabric 3-gallon pots. NOTE: we did our own experiment regarding the type of container and found that the plants in fabric grew much bigger than those in plastic. They are under 450w lights at 24" for 20 hours on and 4 hours off. They were on "vegetative" lights until they started blooming and we switched to "blooming" lights. So they've been on "blooming" lights since around week 5. Too early?
They all germinated well and started blooming at 4-5 weeks. I started feeding them at 5 weeks with General Hydroponics FloraNova Grow & Bloom. I have been following their guidelines for feeding, which means feeding 450--650 ppm for weeks 5 - 7, mostly using 600ppm. The problems started at week 6 with yellow tips forming on leaves, lower leaves yellowing and some leaves have splotches of yellow. Please see the photos. These were taken at week 9. Please advise: what are we doing wrong?
Thanks so much!
2shady

 

[Farmbuck]

What is your PH ? Normal at the end to see some bottom fan leaves yellowing. Also the next time try not using Miracle Grow a lot of growers are not happy with it.

This will help you to understand : https://www.growweedeasy.com/cannabis-flowering-stage

As for Miracle Grow read this : https://wayofleaf.com/cannabis/growing/is-miraclegro-good-for-growing-marijuana

 

[Gingerbeard]

I was considering that Farmbuck . About Miracle-Gro soil. That stuff is already pretty hot with nutes. The last MG potting soil I had said it was good for nutes for six months. Adding nutes to a hot soil isn't good. I'd say flush the h-e-double hockey sticks out of them and maybe throw in some Cal-Mag. Get some molasses going, too.

Looking at the buds, I'm also considering the age of the plants. 5 weeks of flowering puts it close to autumn. This might be a simple late flowering nute deficiency.