How do I transplant 3 week seedlings in straight soil, no cubes

Ok, oldie but a newbie here. A dude I know started 21 seeds, all in a rectangle planter together. And none of them are in rockwool or any type of starter cube just plain starter soil. They were 2-4 inches when I got them, but now with my t5 flo's (an inch above highest plant), ventilation, fan, and humidifier, they are 4-7 inches and have 5-6 nodes each and 5 inches across at top leaf. So my question is...since this dumba** didn't cube them, when can I trust they have enough root to move. And how do I make the soil firm enough that it doesn't fall away from the root when I move each one. They are about 3 inches apart and I'm afraid I'll kill them by moving transplanting them, but know they won't do anything in this planter.

I tried moving one of the smallest ones (in case I killed it) when it was 2 inches and when I moved the soil with a small hand spade the soil fell away from the plant and it had hardly any root (like tiny hairs about an eighth of an inch long). I tried putting it in a jiffy starter cube to save it but it died 3 days later.

What do I do? All suggestions are more than appreciated...!!!

Well, it's been over 48 hours since I posted the above questions and got no help. So I had to do the transplant on my own. Hope they hang in there.

yea thats fine they should do good

its all about the stress Nanna when you transplant your going to add stress.. but I wouldnt be going crazy just yet, your tiny one died because it sounds like it was weaker and less established with the roots most likely because it was fighting the other 20 something plants for nutes and water.. you should have luck with the other stronger looking ones with a more established root growth can take a little more stress..

I would water them with a very light water + nut mix.. just make sure rw holds water very well (too well) so you dont want them soaking wet but moist

ps. it was a good move to transplant because if its been 3 weeks and your still referring to them as seedlings they definitely didnt have the right space to live in, you honestly didnt have much of a choice but not all is lost

They sound like they are more than ready to handle a transplanting... I have grown veggies, flowers for 15+ years and am on my first MJ grow and have transplanted thousands of seedlings (not to sound like I;m some kind of plant guru... cuz I'm not!!) but I've transplanted my Pakistan Ryder plant 4 times - into a bigger pot - and we're doing GREAT.
Just handle them carefully... give them a bit of a watering after transplant and they should be fine... plants are a bit tougher than we give them credit for sometimes...
Good luck brother.
~peace~