eracet, a going to put this simply: Dump those plants in the garbage...soil and all. Wash the pots that aren't disposable *very* good with soap and water and bleach and toss the disposable ones. Seriously, dump them all.
Something has been very, very wrong with the attempt at growing the peppers. I don't know what it is, though.
The problem could be that the plants simply were not cared for properly (no offense intended). If they went through multiple cycles of drought and flood then that could have stunted them badly. Letting them dry out and stay dry for a while will harm them greatly...kind of like us walking across Death Valley with a 16oz bottle of water...it wouldn't work. Flooding them to make up for a drought situation won't really help much once the harm is done. Conversely, keeping them wet can encourage root-rot, fungus, etc., along with depriving the plants of oxygen...it would be kind of like us trying to breath underwater...this won't work, either.
It could be that one of the ingredients in your soil mix was toxic, having some type of herbicide or other toxic chemical in it. That is definitely a possibility but about impossible to know for sure.
I would recommend *not* mixing your own potting soil and to purchase a bag or two of a good potting soil. One that I've been using and is available around here is Baccto. I'm sure there's something in your area that is good stuff. Find a good nursery or farmer's co-op and see what they recommend. If the first thing off of their lips is "Miracle-Gro..." be nice and check other places. Sometimes Miracle-Gro soil is ok, but a good nursery or co-op usually will carry a more commercial(?) grade potting soil (but may have MG soils, too).
I hate that you've had this trouble with your peppers, but I wouldn't waste anymore time on them. I see none in that picture that look like they're doing ok. Toss'em all and write it up to experience.
What I do:
I use a good potting soil to start my seedlings. I've been using "Pro-Mix Vegetable & Herb" to start my seedlings with, but it is getting hard to get around here so I've been using the Baccto some and it seems to be doing the job. The Pro-Mix brand originates in Canada so you may have better access to it than I do...it's really great stuff! Otherwise, if you have to get a bag of Miracle-Gro potting soil. Don't get any "top soil" or "container soil"....*only* POTTING SOIL.
20oz styrofoam cups are really cheap and work great to start seedlings in. Take a sharp pencil, stick the point into the side of the cup just above the bottom and spin it around in the hole a few times...this makes a nice drainage hole. Repeat this so that you have two or three drainage holes in the cup.
As you beginning filling and planting the seeds first take a marker and write the name of the pepper on the side of the cup. Open and use one seed packet at a time. Do this as you plant each variety so that you know you're labeling them correctly.
Moisten the potting soil some...don't saturate it, just wet it some and stir it good...you can do this in a large pan or plastic container. Potting soil can be hard to wet once in the cup/pot so it's better to pre-wet it before putting it in the cups...after that it is easy to keep it moist. Fill the cups and slightly firm the soil down in the cup.
Take the sharp pencil and make two or three holes in the soil to plant the seeds in. I usually let the point go in up to where the paint is still on the pencil (unsharpened area)...then when you firm the soil back over the seed you've got roughly 1/4" of dirt over it.
After you have all the seeds planted water the cups well. Next, you need to put them in a tray or box that you can loosely cover with some plastic to hold moisture in. I don't like to completely seal them inside a bag being as I do want fresh air to be able to get it. I put my seedlings in a plastic container and lay a piece of plastic over the top of the container and cups, leaving a few gaps around the edges.. I use recycled plastic bags that ice comes in to cover mine with, you can cut them open to make large sheets of plastic or if you've only a few cups you can slide them inside the bag...the lettering on the bag doesn't matter.
Place the semi-sealed container in a warm room. Peppers like it warmer than most other plants but if you can get them in a mid-70's temperature that will work. 80F would be better. Be patient, pepper takes longer than tomatoes to germinate. But check them everyday to be sure they're moist...some condensation on the plastic covering is good...but, you don't want it soggy.
Start paying close attention at about a week. If you see a single seedling breaking the soil surface take all the cups of that particular variety and put them under your lights...the rest will follow in short order and you want them greeted by that bright, life-giving light!!! As you see different varieties break the soil surface move them beneath the light.
As insurance I've started putting my covered, germinating cups close to or beneath my lights just so if a seedling pops up it'll at least be getting *some* light from the very beginning. Be sure the lights don't overheat the covered cups, though. It's whatever you feel good about doing.
I use 4' florescent shop-lights...primarily with daylight (5000k temp) bulbs in them. I have three fixtures situated side-by-side fixtures and usually grow two rows of seedlings beneath these. I'm not sure what your LED lights are like so you'll have to figure out how to arrange your plants beneath them. With the florescents that I use I keep the seedling 1-2 inches from the lights. I believe in purpose-built LED grow-lights that the distance is much greater than this. I can barely feel a little heat coming off my shop-lights when I hold the back of my hand the same distance from them as the seedlings are from them. Don't cook your seedlings but give them all the light you can.
I start out running my lights for sixteen hours straight. I give the seedlings 8 hours of darkness. I usually run the lights from around 6am to 10pm. Sixteen hours.
I use a weak mixture of Scotts Bloom Booster water soluble fertilizer for the seedlings once they have their first or second set of true leaves. I usually feed them every other watering.
I usually water the seedlings every three days to begin with, but I check them daily. As they get larger they require more water and watering moves to every two days (but still keeping a check on them everyday in case for reason they dry out quick). Never let your seedlings dry out....NEVER! You want them to start growing good and to never stop growing. In six weeks, eight weeks max, the plants should be ready to go into the garden after several days of hardening off (brief visits under the sun, increasing the time a little each day). I'm not real good at hardening off my plants and they seem to do ok with two or three days of visits outside before going into the garden. You can actually grow your seedlings outside once you get them going but you have to be careful the sun doesn't burn them or dry them out quickly...there's more control beneath the grow-lights.
That's pretty much what I do. I've got a jalapeno in a pot that is pushing 2-1/2 feet tall and probably has 50(?) peppers on it of all sizes. This was a "left over" plant that stayed under the growlights for *way too long*. I threw it in a pot of old recycled potting soil from several different pots with a little added fertilizer. This plant had really been just surviving in the 20oz cup for months and now it's going gangbusters. That's why I think your plants have something amiss about their growing medium. If this little jalapeno can go from an ugly duckling to a pretty nice-looking swan certainly your plants should be big and healthy if something wasn't terribly wrong.
Something is indeed screwy about your plants' health. I'd get rid of all the soil mix and plants and start fresh with a known good soil. Follow some of the things I mentioned above and you should be growing some nice plants. It seems that you've got some nice LED growlights, just be sure to use them correctly. The blue lights encourage vegetative growth whereas the red lights encourage maturing and blooming. Personally I'd run both sets for the most lumens...I've pretty much always had a couple of lower Kelvin temperature (reddish) tubes in my shop lights and the plants seem to do well.
Anyhow, don't let this sour your goal of growing peppers. Take it as a learning experience. Dot your "i"'s and cross your "t"'s. If you want to really grow some good plants you've got to put effort of time and thought into it. It's not something you can think about every now and then...those plants can't go get a drink of water by themselves and they do need some nourishment all along. If you're going to grow them....grow them.
Best wishes,
Ed
