Seedling fan leaves have turned yellow

[co_grows]

Hey everyone, I have just started my first indoor grow. It is a 5x5 tent with 600w HPS. My seedlings all germinated within 24h and I was off to a great start. I noticed about 3 days ago that the first set of fan leaves have started to yellow. They are still perky and soft. Not light burn or anything like that. Light is about 3ft from plants. The temps range from 61-81 and the humidity is pretty low. Usually around 25%RH. Plants are in FF Light Warrior and I have been watering with 6.8ph. I let the plants sit in a large pot holder for a few days just to make sure the soil stayed moist. I think that resulted in the soil being too moist. Any help is appreciated.

[Viz]

Over watering is what it looks like to me.


What light are you using?
What are you growing your plants in, coco, soil? Soil will buffer the Ph so you do not have to do anything with that. Coco of course does require more work.

[GSIntegral]

I see a little yellowing on some. Other than that it looks like new growth (usually a different shade of green). I have the same problem with my clones where everything is good for a while and then my fan leafs (first set) will yellow and die off on the bottom/underside of the plant but the new growth is always a good color. This is only my 4th time around. I've asked my local shop about yellowing. They mentioned fan leafs will do this as it gets older and bigger. I've only noticed it when the plant is becoming more mature or at least 6" taller than yours though.



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[co_grows]

Apollo 600w HPS light. Fox farm light warrior soil. I removed the pots from the tray filled with water a few days ago and have been letting the soil dry out. I haven't noticed any change. Strain is Northern Lights Auto.

[Samwise Gamgee]

Let them dry out till they are bone dry, it looks like lack of oxygen to the roots, caused by over watering

[co_grows]

Thanks for the help Samwise Gamgee, GSIntegral, and Viz. I suspected over watering and will let them dry out real good. I will keep an eye on them for the next few days and post an update, hopefully a good one.

[Joe Dirt]

25% humidity did you say? That's you problem there. You need least 50%. Get those guys domed. I literally am just going through the same thing. My RH was 30. My clones were yellow and drooping. I added a humidifier and brought the RH to 50. They all have perk right back up by next day. Cut water bottles and place them over the seedling. Good luck.

[co_grows]

I bought a humidifier to help with humidity. Brought it up about 5%. I have a tray filled with water on the floor and it still wont go above 25%. At night when the fans are off the humidity will rise to around 60%. During the day with the fans on the humidity always drops to 25% while bringing in the dry Colorado air. Being in southwest CO the ambient RH is always pretty low. I have the light on 20/4 so not much time at night to get the humidity up. I will try the domes and see if it helps the little ladies. Thanks Joe Dirt!

[kbag]

There is a few things here you could try to help your plants. Run your dark period when your ambient R/H is at its lowest. You could use a m/halide or a T5 or lower the wattage of the hps all 3 will help raise the humidity. You can use any of the 3 in veg then bring out the 600w hps in flower.
No need to ph in soil as already stated and keep your fans on 24/7 its a must do. The domes will be good as a temp measure whilst you can try to dial in your environment.

[co_grows]

Thanks kbag. I have done a few things to try and raise the humidity. I have a large surface area tray filled with water and a box fan blowing on that. I also added a 5gal bucket of water in the corner. This morning I cut some plastic bottles and made individual domes for each plant. Now about the light. I have two lights, both the same brand (apollo). One ballast is 600 the other is 1000. Both are adjustable. Initially I have started with the 600w HPS at 50% power. Fans are on low to keep Temps down. I intend to switch to the 1000w set up after the plants get bigger. It looks like the leaves are starting to green up a bit. At night I have the fans turning on low for 15min every hour to refresh Co2. I don't have them on 24/7 as suggested because I want to let the humidity build up in the room. It is the only opportunity to do so.