Seedlings In Rock Wool - Too Small?

Hey, guys. Longtime outdoor grower, doing an indoor project for the first time in over 20 years. This is the first time I've ever grown in rockwool, and I'm a little puzzled about how it's going. The seedlings aren't following the progression I was expecting.

Here's the deal. We have 11 white widow seedlings in 4x4 inch rockwool cubes (I know, probably too large, but live and learn.) The seeds all sprouted on about the 1st of February, 2 and a half weeks ago. Currently, 10 of them are about an inch and a half inch tall with the second set of leaves popping out. 1 of them is a little taller, and much more fully leafed out. The thing is, all of them have long roots coming out of the bottom of the rockwool cubes already.

We have them under a 400-watt MH light, hung about a foot and a half above the plants. We're feeding them 1/4 strength HydraGro in distilled water. I was frankly expecting them to be growing a little faster by now, and I'm confused that the roots are growing so long and so fast while the stems and leaves are still going so slowly.

Does this sound right? The plants seem healthy, but I'm not sure having roots coming out the bottom of the cubes is the best thing for them. But we really don;t have the room in the vegging chamber to put them into the clay pellets and pots yet. Anybody have any thoughts on this situation? We on the right track here, or should we be doing something differently? Thanks in advance for any help.

Yea if they have long roots coming out thats different. I wouldnt think thats a bad thing though. What method are you growing these? Do you just have the rockwool cobes on a tray or something? My brother grew part of a veg cycle with some 4x4 cubes on a tray and had them drip fed. The roots dod show for a bit before he added hydroton. I believe he had problems and thats why the hydroton was added; to cover the roots. Normally the problem would be the roots drying out. Plus all the other risks of haveing your roots exposed such as bugs or algee growth. But if your roots are bright white they are ok. As far as the plants being 1 1/2" tall for being 2 weeks. That doesnt seem to bad. I just started my first soil grow and I think they look different then hydro(I use DWC). I wanted to do soil so I can transplant them to the great outdoors. For me it seems hydro doesnt start growing really fast until after the first month. Then it will take off. Just takes alittle time to settle into is surroundings I guess.

I think starting in rockwool is a little slower than dirt or rapid rooters because I'm in the same boat right now but, hopefully the root system is just better thats why the top of the plant slows?

Thanks, guys, I appreciate the help. Yeah, they're just in trays, and we water them several times a day - just enough to keep the cubes moist, not enough to flood the trays. Do we want to elevate the cubes before adding the hydroton - put the cubes on a layer of hydroton? Or just let them sit in the trays and pour the pellets in around the cubes?

I dont think it would make to much of a difference if you have the cubes on and surrounded by hydroton(putting the hydroton on the tray then putting cubes on top and then also putting it around the blocks), or just having your cubes surrounded(keeping the blocks on the tray and then dumping hydroton around them). I could see on benefit for having them on the it but I dont know if it would really matter in your growing system. The benefit would be for drainage purposes. Basically so the plant wouldnt be sitting in stagnet water. I just thought of a video I watched on youtube called "I grow Chronic". He grew like you are now. Then he moved his plants to another tray with a shit load of hydroton in it and buried the cubes. Also thanks for the +rep.

here is your problem, you are giving your roots too much space too fast,and also too many nutes.. if you look close at your 4x4 cubes you may see the center 1x1 is precut this is for a reason, so you can start small. doing this makes a 1x1 compact mass of roots. once the roots are sticking out of the 1x1 on all 4 sides and bottom of the cube then incert into the middle of the 4x4 now you roots can take advantage of this new space instead of shooting down throught it with the only root it has. keep the seedlings in the 1x1 cube in a cooler room ,on a heat pad in a hum dome,but only give them one drink when you first put them in their. after that just mist the inside top of the dome after all the drops are dried off. if the drops dont dry off the dome then turn up the heating pad not room temp. no nutes at all untill you see a even steady yellow on the leaves then you can start to expermint with ferts, but start with small small doses wait 4or5 days and if no burning then add a but more untill you find your strains sweet spot.. oh and the alage and mould can start growing on rock wool 10x faster with light present, probley the only reason you may cover with clay pebbels probley a good idea, well better than nothing anyways..