New Grower Seedlings stop growing every time...

[GreenThumb]

Hey guys (& gals...)

I keep having an issue with my seedlings where they stop growing at the same point every time.

I'm growing DWC in a temp controlled cabinet.

I've tried varying air temps from 74f to 84f and get the same results. Tried 3 different autoflower strains including Dutch Passions Think Different, Afrodita La Bella and now using an AK47-based auto strain.

I'll post my current temp settings and lights


82F (Under lights)
RH 60-70%
Hydro 70F
Light is a 90w metal halide mounted in a cool tube 4" above the seedlings
Tried rockwool and rapid rooter plugs

OK, so this last attempt I switched to rapid rooter plugs. Soaked 2 seeds for 24hrs in distilled water, placed in rapid rooter plug, they germ'd and each one dropped a single pearly white root out of the bottom of the rapid rooter plug within 3 days. The seedlings broke the surface, cotyledons opened, no problems there. I hand watered with 5.8pH distilled water, no nutes at all, 5ppm reading doing a wet/dry/wet cycle.

I noticed good biological response to the light source as they stretched towards the light source and began to grow the first set of true leaves.

This is where every time things get confusing. At this point, they just stop progressing or progress VERY VERY slowly. I'm on day 6 and have not seen any new growth since day 3 or 4. The stems have a red shade that slowly fades moving up towards the leaves. The stems have a light coating of hairs like a "peach fuzz". All in all, they appear to be healthy, they just won't grow.

I'm at a loss because everything I've tried from different temps, humidity, medium moisture, metal halide or CFL, I get the same result. I've gone through at least 14 seedlings now of different strains including 2 photo-period bag seeds.

I had some of the prior attempts grow slightly more, developing slightly larger leafs and even second sets, but they ultimately begin to yellow starting at the leaf tips and moving inward. Never using any nutes, only pH'd distilled water.

What the hell am I doing wrong? I can't seem to get past the seedling stage!

 

[tremane]

I'm a newbie but it doesn't sound to me as though you're doing anything wrong - it all looks fine. Autos really don't like to be transplanted, as they're more likely to get stressed than photos, and I've read they do better being started in larger tubs, would it be worth trying to plant a seed in a bigger tub (2-3 gallon) and see how that goes? My 22 day plant has such an enormous root system that it's already poking out the bottom of an 11 litre (just slightly smaller than 3 gallon) tub, so it could just be that it needs room to grow past the seedling stage?

 

[mclovin478910]

where did you get your 90w mh? and what brand? and also how many cfls were you using everything seems like your doing ok, i had alot of trouble getting seeds started until one finally popped. It took me 12 seeds and 1 finally made it past the first week. sometimes its just genetics arnt strong enough.

 

[C.E2]

You need atleast 0.6 ec (300ppm hanna, 420 ppm truncheon) in there of nutes.
Distilled water with soilless/hydro medium is a nono. Ph-ing doesnt make any sense, as pH of RO/distilled is too unstable, due to huge shifts in pH as moisture of medium changes.
Also looks like your medium is too wet at times, atleast in the picture you posted.
I advise you to move to coco, its water retention is great and its hard to overwater with it, but u can just keep what your doing and just adjust your EC.

Also, use rhizotonic or any kelp additive, but rhizo is highly recommended if you can get it. Also, use ph- flower as the phosphorous encourages root growth especially at low ECs like 0.6.

Cheers

ps: Hand water your seedlings until they are a few nodes big before moving them to DWC. DWC directly for seedlings is dangerous even at low ECs, as the roots are in direct contact with a constant supply of fresh nutes.

 

[GreenThumb]

Tremane; They really are not developing a strong root system to begin with. I don't think it has anything to do with the size of the system they're in.

mclovin; A friend had the lamp sitting around, it's a GE... I don't know much more about it. I was using only 1 40W 2700K CFL mounted in the cool tube with reflector & set 3" above the 2 seedlings I was attempting to grow at the time, this was about 10 or so days ago now. I had no luck with it so I switched back to the metal halide and started new seeds, the ones you see in the pictures now.

I had same results with Dutch Passions Think Different feminized auto's and the Afrodita La Bella feminized, and every other seed I've tried lol.

I was just reading a post on Grass City forums and this guy started nutes on his auto seedling 3 days after they sprouted and within 7 days had an impressive plant. I just now followed the advice from that guy and dipped the plants in 300ppm of GH FloraGrow pH'd to 5.8. Not sure if this is going to kill them or not but at this point, I'm willing to try. I also started soaking 2 new seeds today and plan to follow this guys technique right from the start. He got this advice from a licensed medical grower on the forum, jakesterjammin.

Check it out... http://forum.grasscity.com/hydropon...al-sensi-star-6-sq-ft-scrog-single-plant.html

 

[GreenThumb]

You need atleast 0.6 ec (300ppm hanna, 420 ppm truncheon) in there of nutes.
Distilled water with soilless/hydro medium is a nono. Ph-ing doesnt make any sense, as pH of RO/distilled is too unstable, due to huge shifts in pH as moisture of medium changes.
Also looks like your medium is too wet at times, atleast in the picture you posted.
I advise you to move to coco, its water retention is great and its hard to overwater with it, but u can just keep what your doing and just adjust your EC.

Also, use rhizotonic or any kelp additive, but rhizo is highly recommended if you can get it. Also, use ph- flower as the phosphorous encourages root growth especially at low ECs like 0.6.

Cheers

DUDE, THANKS!!! I avoided nutes out of advice from another grower I talk to who says that he doesn't feed for weeks. I know a thing or two about plants as I do successfully vegetable/fruit garden every season and it makes NO sense to me that after the plant sheds it's seed husk (where it's initial food is stored) that you can go weeks without giving any type of nutrient and expect growth. Yet I constantly am told that any nutes will kill the plant and that it doesn't need to be fed for at least 2-3wks. Distilled has no nutrients at all and you're absolutely right about the pH fluctuations!

I'm glad to see you saying what I've been thinking.

As for the moisture content, yup, their wet as I just dipped the entire rapid rooter plug in a nutrient solution. I'll leave them to dry out now until I wet again.

** I did 300ppm hanna of GH FloraNova Grow; http://generalhydroponics.com/site/index.php/products/nutrients/nova_series/nova_gro/

I have some Organic Neptune's Harvest Fish and Seaweed fert, it's 2-3-1 - Should I use this over the FloraNova? The FloraNova is packed with micro nutes as well, not sure what the micro content of the fish & seaweed fert is. http://www.neptunesharvest.com/fs-191.html

Not to mention that distilled water by itself will pull minerals out of a living cell. I know that human consumption of distilled or RO water isn't good because you'll end up pissing minerals out and not restoring them.

 

[GreenThumb]

ps: Hand water your seedlings until they are a few nodes big before moving them to DWC. DWC directly for seedlings is dangerous even at low ECs, as the roots are in direct contact with a constant supply of fresh nutes.

Should I just set the water level to a few inches below where the net pot hangs? Or would it be OK to plug the hole in the DWC container with a small plastic cup, then set the net pot in there? I have some 3oz Solo cups that the 2" net pots sit perfectly in, so I could drop one of those cups in the hole then put the net pot in it so that way it's in the cabinet and in the DWC container but the roots will grow out of the rapid rooter and fill in the cup... Get what I'm saying?

 

[C.E2]

If u dont have anything ready for the DWC simply don't load it up with water/nutes. Just make a water mix and water ur plants by hand.
When ur plants are ready for dwc (~ 2 weeks old ?) set the water level to just below the nets so that the bubbles are still splashing the net/medium/roots.

 

[GreenThumb]

That compartment in the cabinet is only for seedlings. It's setup so I can do a perpetual harvest, so it will always be stocked with seedlings, some a day old and some perhaps 2 weeks old. Just depends on when the plants in the next compartment are harvested, then I can flush that system and move some seedlings over. I do not have any air stones as it's a recirculating system and I don't want the bubble splashes to soak the medium.

Any advice on how I can run this? I was thinking that if I kept the water level low enough that way new seedlings wouldn't get down to the water but the older ones would have roots long enough to get wet. I have a fogger in there to keep the shorter roots from drying out.

 

[C.E2]

Honestly ?
If you can get some coco coir and just grow in it using the same bottle of nutes you will be way better off. Way simpler, and if you do it right, same results yield wise, with better taste (7L Pots). I made a grow guide for coco once dunno if its still here after the site went crashing a few weeks back.

Its not just a matter of water level, there should also be different EC, different npk, etc.
I don't see a way you can really pull off a perpetual setup on a single DWC with several slots on.

I've had a few friends go DWC and go back to coco and now they swear by it. I went hydro (hydroton) too and came back.
Can't give you much advice on DWC as I've never done it myself so can't go into those specifics, sorry.