Plants Stopped Growing after put them in 12/12 cycle. Please Help

Okay, This is my first time grow. I am working with 2 plants from bagseed.

I am doing a DWC with 400 watt HPS for flower. I vegged the plants with (5) 75 watt daylight cfls on a 18/6 cycle for 3 weeks. I know thats a short veg cycle but I am on time constraints.

The plants are now on their "transition" week from veg to flower. I put them in a 30 hr dark period before starting transition to hopefully have them show sex a little earlier.

I am using GH nutes and gave them the recommended amount for the transition stage.

My problem is, ever since the 12/12 cycle (3 days) they have siezed in growing. The plants themselves look healthy still, and the roots seem to be growing but the plant has stopped. Could the plants still be in shock?

My PH is a little low, around 5... could this be the problem? PLEASE HELP!!

I'm not an expert by any means, but when I switched to 12/12 my plants didn't grow for 3-4 days either. But then on the 4th or 5th night they took off like wild fire! Mine still grow more during the 12/12 night cycle.... Based on what I have read here and experienced on my grow - just bring your PH up a bit and check the ph run off from your plants when you water them. Give it another day or two and I bet they start growing like you have never seen.

sokarempire said:

I'm not an expert by any means, but when I switched to 12/12 my plants didn't grow for 3-4 days either. But then on the 4th or 5th night they took off like wild fire! Mine still grow more during the 12/12 night cycle.... Based on what I have read here and experienced on my grow - just bring your PH up a bit and check the ph run off from your plants when you water them. Give it another day or two and I bet they start growing like you have never seen.

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Agreed, mine took a couple days as well, but a heads up the "STRETCH" is coming, so keep the light close and give it just a LITTLE extra N for the first week or two or your tops now will look leggy in a few days (trust me).
And make sure while keeping the light close (not too close to burn of course), be more concerned with raising the light in the morning then at night as they will do most of there height growth at night during this time. Also if you haven't been now is the time to refresh your micro nutes, MG, zinc, and all that.

-edit Oh I forgot to say your ph ideally should be 5.8 that allows the highest % of all combined nutrients to be taken up in a hydro set up.

Thanks for the input. As this being my first grow I'm sure I'm like most and over analyze/over react over every little thing.

This is the third day on 12/12 so hopefully I will be seeing some growth in the next couple days.

I will keep you posted.

Dmnspawn - How close should the light be to the plants... its roughly 16" from the top of the tallest plant right now.

Striz said:

Dmnspawn - How close should the light be to the plants... its roughly 16" from the top of the tallest plant right now.

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Depends on the Light, you said it was a 400Wm without knowing how much airflow, fans, is it in a cool tube? glass lens? ballast attached or remote? And depending on how High discharge the bulb is (not all 400W bulbs are the same) one may have 52,000 lumens and others may have 61,000 but obviously the bigger it is the more heat it will generate.

I myself have NEVER used a 400W I'm useing a 250 watt with louvers with a glass lens and It's COLD where I am right now so I actually have to HEAT my room.
So I can get mine REALLY close if I want but I still keep it at least 8 inches away anything closer seems to shade the bottom 1/2 of the plant.

For yours if it's just a normal 400w with ok airflow, and you can maintain the temps in your room to below 80F I would say at LEAST 12 inch away. minimum, now this is if you put a fan blowing on or around the bulb, if not then I would say higher, so your 16 is probably fine.
A good test is to put your hand under it, if it feels uncomfortable move it up, if it is like laying in the sun on a nice day, warms your skin a tad but not irritated, if your hand is red AT ALL afterwords it's to close even if it didn't hurt. Now for best Lumens for your bulb that won't Bleach your plant you can go as close as 6. if you were just making one HUGE cola. **Also assuming you could keep it cool that close and still be under 80F.

I think that for you between 12-16 for the best lumens/heat ratio. I would keep it around there at all times if you can, AND keep your conditions below 80F and 60% humidity.
After it's been there for 1 week you can experiment with getting a little closer but I still wouldn't go closer then 10, playing with fire at that point.

dmnspwn - thanks for the great detailed replies. I appreciate all the input I can get.

An update on my plants...still very little to no growth, the plants themselves still look healthy and the roots are growing like crazy but still very little vertical growth. It has been 6 days since the 30 hr dark period before putting them on 12/12.

The plants height before putting them on 12/12 were around 6" and now they are right around 7"... i mean i know an inch in a week is something but from what I've read from other people's experience my plants should be stretching a lot more.

Is there anything else I should be looking for, or am I just playing the waiting game?

If your roots are growing rapidly, then get ready for a good stretch. I started my plants on 12/12 on march 21st @14" tall, Today they are 39" and growing. But it took 3 or 4 days for them to really get going.

atombomb said:

If your roots are growing rapidly, then get ready for a good stretch. I started my plants on 12/12 on march 21st @14" tall, Today they are 39" and growing. But it took 3 or 4 days for them to really get going.

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you don't want them to stretch, try to give them a little extra blue light lie a cfl or 2 to help stop the stretch also give just a LITTLE N to the plant and it will stop the stretch, also dont let the lights get too far away for even a little bit or they will stretch, if you dont overdue the N and give extra blue for the next 10-12 days and dont let the hps get too far away it shouldn't stretch and form a dense stem. which can hold more weight he he. Also if it's only been 6 days it's not done doing nothing, mine both did nothing as they started to form little popcorn buds and the moment i saw them BAM stretched and then budded heavily. just wait a bit and youll see them flower.

ok...i would think that the answer would be simple and that the extended dark period b4 switching messed with the plant....to show sex u need to flowee if it doesnt show after a couple months