yellowing leaves in seedlings

[Tribs]

Hi,

I have a grow room of one cubic metre, with two 150 Watt HPS, and have six week-old seedlings in soil. The leaves have turned half-turned yellow, and the new growth is yellow. The temperature is 20-30 Celsius, humidity of 50%, and I spray them a couple of times a day with tap water. They're on 16 hours of light.

I don't have any pictures just yet, I'll try and get some tomorrow.

Anyone know what's wrong?

 

[vanbuilder2]

20-30 degrees is a big difference. You need to keep it consistant. Try 24/7 hour light. 6 weeks is a good time for vegging.

 

[ultimate procrastinator]

how can you have a seedling that is six weeks old? Doesn't the seedling stage last 2-3 weeks at most?

 

[Tribs]

I meant 25-30, my bad.

And by "six week-old", I meant that there were six of them, and they're all one week old.

 

[vanbuilder2]

okay, first don't spray them. Just water when needed. If they are a week old and are yellowing are you giving them nutes? If so. Stop. They don't need them for a while. Seedling just need water.

 

[vanbuilder2]

Put a pic tommorrow and someone can help you. What lights, soil, temp, etc. They are still young and could die easy. If the leaves are wilting and the soil is damp don't water. I think the biggest problem with dying seedlings is over watering

 

[Tribs]

I haven't been giving them nutes.

And won't changing from 16 hours to 24 hours confuse them?

 

[ultimate procrastinator]

I meant 25-30, my bad.

And by "six week-old", I meant that there were six of them, and they're all one week old.

ah my bad, the hyphen indicated your meaning, your grammar was correct

 

[Tribs]

Here are the pics. Any ideas? My guess is the PH, 'cause I'm doing the exact same thing as I did about a year ago, and the last crop was fine. But you're the experts

P.S: When I said 16 hours, I meant 18 hours... I was baked when I posted the thread hehe. And will changing from 18 hours to 24/7 confuse the plants?

Thanks in advance.

 

[iamdrpepperful]

And will changing from 18 hours to 24/7 confuse the plants?

No, it shouldn't. If your plants are vegging and you increase the "daylight" time, you will be okay. This happens naturally in nature, when spring comes around there is less daytime than there is when mid-summer comes. Once mid-summer passes and the days get shorter then flowering begins. Switching from 24/0 (or 24/7 same thing) to 16/8 might mess with it a little though.