They are outdoor plants. The leave sets continue to try and grow but imagine them laying on the edge of the grow cups pointing upward and this long, lazy, thin stem running back to the center of the cup.
Hiya VH
To be honest, it's far better off to start seedlings off under artificial lights where you can control the environment far better than if they were outside. Seedlings (and clones) are very vulnerable in the first two weeks of life and need a constant supply of water, warmth and light to help bring them on. They also need a gentle breeze on them for the first couple of weeks to help strengthen the stem if they're being brought on inside.
Your problem could be caused by too little light or too much, the sunlight might be overwhelming the little seedling and causing it to fall over. Seedlings (and clones) require very little light in the first couple of weeks as most of the growth going on is underground - not above it.
I just keep thinking they've been getting burned by the strength of Happy Frog soil that while it doesn't have any added "nutes" it does have guano and worm castings- I have a paper that says worm castings won't burn any plants. I've seen young plants get leggy or lazy with too much nitrogen and it wore off after a couple days without water or nutes which is what I thought these would do but maybe they're not adapting like that because nitrogen isn't the problem.
It's quite possible this might be part of the cause. I posted a thread on stretching recently and insufficient light was only one of many causes of stretching, it amuses me that people immediately point at the light whenever anyone mentions stretching. Low light levels are only ONE cause of stretching in plants - there are many others and large light/dark temperature fluctuations is one of the biggest causes. As is having a constant supply of light hitting one side of the plant but not the other, this causes the two stem halves to grow at different rates and can cause plants to fall over.
One of the tricks to using the 'same nutrient strength' soil for both propagating and vegetative and flowering growth is to vary the amount of perlite/vermiculite you use in it. Obviously any soil amendment (like perlite) will remove nutrients from the soil, with regards to seedlings this is what you want - so amend the soil with up to 50% perlite to help reduce it's 'hotness'. I find a 25% Perlite and 5% Vermiculite mix works well with seedlings, the Vermiculite to help store more water and nutrients and slowly release them over time than Perlite. Vermiculite can hold up to 150 times the water/nutrient content that Perlite can hold, so use it in lower proportions to Perlite.
When it comes to potting the plants up for Vegetative growth, I usually drop that down to 5% Perlite and 5% Vermiculite 90% soil, as I want as little soil amendments in my mix as possible as I want more of the nutrients. The fact that I continue to use Perlite/Vermiculite at all is simply to make up for the deficiencies of your average potting soil - it's not well draining on the whole, when I find a good one I'll probably stop with the soil amendments completely.
People 'like' the safety net of Perlite in their soil - it helps to retain moisture and nutrients because it can absorb more of them due to it's larger surface area and then release them slowly over time - this helps to extend the watering time and is less forgiving of allowing the soil to dry out completely. It also helps the drainage and 'compaction' of the soil due to too much clay/silt. If you use a high quality, well draining compost/soil, there should be no need to amend it with anything at all, unfortunately there isn't many about if at all!
fdd, regarding replanting, if I bury them up to the leaves that's not going to cause the stem that's been above ground to rot or die? I thought about replanting like that but imagined the stem above ground is different material than the root system below ground- just like leaves don't grow underground stems would turn to mush and rot underground, no?
No basically. The stem simply becomes more of the root system. If you grow out your plants to maturity - you'll see the plants try to put out roots from the stem at just above the soil line, and you often see surface (or just below the surface) roots like that in older plants.