I don't remember if you bought that General Hydroponics kit that comes with bottles of PH UP and PH DOWN? That is the best stuff to use for adjusting your water and feed solutions to the optimum pH. I adjust all my feeds to 6.5, but water with unadjusted well water that is always at a stable 7.0.
I'm going to take some time and lay some stuff out for you to refer to later. Maybe print this post out and keep it for future reference. All I am going to provide here are some gardening basics related to Cannabis.
First of all... That one application of Miracle Grow wasn't the cause of your issues with that first plant. The problems started long before you added that. As I mentioned before, I have used a single feed of MG dozens of times over the years to quickly resolve rapidly occurring deficiencies in potted plants. It was just applied too late to help in this case. It is true that you don't want to be feeding ANYTHING to new seedlings less than 4-5 inches tall. They simply don't need your help yet, so just stay out of their way!
The problem you had the first time was feeding and/or watering with solution pH levels in the high fours to mid fives. (ACIDIC) Cannabis has a very high tolerance for alkaline soils and the 6.2 to 6.8 range that they prefer is considered to be moderately alkaline. On the other hand, they have VERY LITTLE tolerance for acidic soils in the mid fives and lower. Some strains will start to go south in anything under 6.0.
Surprisingly, few growers even know this simple fact and become their grow's worst enemy.
The fact that your pH is on the alkaline side of the range now is the only reason your young plants are still alive. If your soil had stayed locked in the acidic end (under 5.5) they would all be dead now.
Most of my pot's soils test out at between 6.8 and 7.0 which is totally fine. You want to shoot for between 6.2 and 6.8. I always stabilize all my pots at 6.8 and have done for decades. Still, sometimes you will find a pot of soil that seems hell bent on something higher like 7.0 or even 7.1. If the plant is doing fine, don't worry about it! Just let it be!
I just
harvested a GDP plant that yielded 1 pound 8.40 ounces trimmed wet weight. That will eventually yield between 7 and 8 ounces of dried bud. This from a plant that was under 35" tall at harvest. Its soil pH was a constant 7.0 for the last four months.
Don't let the weekend warrior gardeners worry you too much. The problems you are having are more complex than a point or two above the optimum 6.8 pH Cannabis thrives in. The transplant into a bigger pot and better soil should turn it around eventually, but don't expect these improvements to happen overnight. It can take as long as four weeks for an ailing plant to fully recover from trauma.
Once you start using the right kind of soil and hold off on the temptation to feed and water your plants to death as so many amateur gardeners do, a new fresh batch of seedlings or clones should do really well for you. If you have never grown anything before, don't expect to raise an award winning plant your first, second, or even third time! This stuff takes practice, and something even more important... PATIENCE!
Maybe look into buying yourself some
Air Pots. These pots will help minimize the effects of slow drainage and soil pH effects on your plant's root systems. They are best used with Coco as the soil medium because you need to pack these tight for them to work their best. But Fox Farm Ocean Forest or Happy Frog will work too in a pinch.
You want to shoot for Coco because it doesn't have pearlite and all the usual drainage helpers found in most potting mixes. These little pebbles can clog the air holes of the Air Pots and make them less effective, but as I said, it will still work better than a conventional container even with standard potting soils instead of the fine grain Coco blends out there.
A good majority of the master "soil container" growers on this site use them. I just recently converted over to them myself and will be using them exclusively next season.
These are four week old Grand Daddy Purple clones growing in Air Pots. Soil pH is 6.85
This is a clone from my award winning Blueberry Kush plant that will be the mother for my BBK crop next year. It was fed a single dose of MG when it was showing some signs like your plants are its first few weeks out of the cloner. Soil pH here is 7.0. Do you see any issues with it now?
All these plants are watered WHEN NEEDED (About once every 4-6 days) and fed Fox Farm Grow Big once every 7-14 days. Ocassionally some Organic Kelp Extract and Molasses instead of the FF. Thats all they need. You need to let your soil dry out in between waterings. The plants need that part of the water cycle just as much as they need the water and the occasional nutes. If you deprive them of their much needed "Dry Time" you are headed for problems.
I don't normally post photos of my own grows in someone elses thread, but I got the indication from a few of the previous comments that I needed to clearly demonstrate through actual results that I KNOW what I am talking about!
Good luck with your transplant, and don't forget to pick up a bottle of Liquinox START B1 transplant solution to water the root ball and soak the new pot of soil with! Your plant is not at its peak of health so it is going to need some TLC in the form of START to help it move forward and beyond its current difficulties.