Roots coming out of rockwool cube

When would be a good time to transplants the cube to soil? Last grow, the roots started growing out of the cubes after like a day or two if being in the cubes, so mainly what I'm asking is what do I do when I see the roots popping (literally) out of the bottom of the cubes, like the root is suspending from the bottom of the cube, will it eventually retract back into it?

Plant it

Its time to pot them up when the roots are coming out the bottom. If the air gets to the roots they will die back its called 'air pruning'. The roots are looking to grow, give them the room to I say.

Cool, thanks for the replies guys. I'll keep that in mind

will it be safe to put them under a 1k then? Because that's the next step, and they were barely just sprouted

I dont use HID for veg so can't truly answer. I believe that it would be wasted just now tho, I'm sure ive read that they cant process much light until the first set of true leafs. Someone who uses a 1k from the start would be better advice

you can transplant it from day 1 if you wanted.

I'd rather keep them under the small light for atleast a week, but I don't know what to do if the roots start popping out the bottom again /:

Right when you start seeing roots, pop it in the soil but keep it under some florescents for about a day or two. Then it will be ready for blue HID's or whatever you have. And if you want super plants get a spray bottle put some clean water, mix in some vitamin B, and a tiny amount of molasses and spray it on the leaves every couple of days for two weeks.

It can go under the 1kw. Just raise the light and ease it down over first week.

let the roots grow out, put a small fan to move air over them. Set the rock wool cube up on a rack of some sort to keep the rock wool off the bottom of the tray. This technique is caller air pruning. the root ball will keep growing up inside using it to capacity. Then plant it in dirt and you should have better growth from it. i think thats how it works