New Grower Cold temps plus low humidity = yellow leaf tips? (UPDATE: Pic on page 2)

[Eljefemoe]

Hey guys, getting started in my very first grow. Check my sig for a link to my grow journal.

Anyhow, the leaf tips on my Critical Jack seedling have been yellow for the past 3-4 days. Just the tips (haha) are yellow, everything else looks good to my eye, but I'm also a noob, so I could be off base.

I've been trying to figure out what the issue was... And I realized this morning that temps have been dipping down to 57-59 at night... It's very cold here and those temps are happening even with the lights on, etc. Humidity is also low, it's been around 27% the last few days.

I'm running a simple bubble bucket DWC grow with a 150w HPS plus 2x 23w CFLs in my 2x2x5 grow tent, the gl60. Water ph is set by me at 5.5 and when it drifts up to 6.1 I adjust back down. I had been using 220ppm tap water, and have recently switched over to RO water (20ppm first reading) that I'm buying from a local store.

Am I on track with the cool temps being the culprit?

 

[Nemesis]

Yo Bro;

Could be a mix of the cold temps and tap water (wrong ph)
I normally ph mine to be 6.3 - 6.5
Am looking into it more for ya

 

[Purple Haze]

That is some really strong tap water to be using for a new plant, I would try adjusting the mix of RO with Tap to bring it down to about 120 at the most. Although I am currently growing a critical jack pheno experiencing the same thing with just its baby cotyledon leaves, could be inherent to the strain. Keep an eye on it and I would ease up on the strength of your water, you haven't fed it anything have you? what is your water temperature? I would also suggest in the future to allow your seedlings to show their first true leaves and a good amount of roots to be exposed through a rock wool cube in an incubation spot, if possible, and then transplant to hydro.

 

[Eljefemoe]

Yo Bro;

Could be a mix of the cold temps and tap water (wrong ph)
I normally ph mine to be 6.3 - 6.5
Am looking into it more for ya

Much appreciated! I've dug around and couldn't find anything specific to seedlings... I know they're sensitive (because I've managed to kill two of them already so far) so I want to make sure I fix this if its an issue.

I think my tap water might have been the problem too. I've been keeping a close eye on it and adjusting (I adjust it right in the bucket with General Hydroponics PH Down solution) as needed. But I think the high ppm coupled with a high initial ph (9.1) might have made it a little unstable.

I will post a pic of the seedling in a few.

 

[Purple Haze]

Nemesis my good sir, he is growing in Hydro not soil. I prefer 5.9 for my ph of hydro but 5.5 - 6.1 is acceptable.

 

[Nemesis]

A snippet from the web,,

Cold - Cold weather (below 50F/10C) can lock up phosphorous. Some
varieties, like equatorial sativas, don't take well to cold weather. If you can keep the roots warmer, the plant will be able to take cooler temps than it otherwise could.

hmmm interesting....
PH - The pH of water after adding any nutrients should be around 5.9-6.5 (in rockwool, 5.5-6.1). Generally speaking, the micro-nutrients (Fe, Zn, Mn, Cu) get locked out at a high pH (alkaline) above 7.0, while the major nutrients (N, P, K, Mg) can be less available in acidic soil or water (below 5.0). Tap water is often too alkaline.

Heres the link bro ;

https://www.greenpassion.org/OG-FAQ/58.htm

 

[Nemesis]

Nemesis my good sir, he is growing in Hydro not soil. I prefer 5.9 for my ph of hydro but 5.5 - 6.1 is acceptable.

Oh yes, I stand corrected. My Apologies Sir.
I Put that link on anyhoo, was a good read, might be useful. :check:

 

[Eljefemoe]

That is some really strong tap water to be using for a new plant, I would try adjusting the mix of RO with Tap to bring it down to about 120 at the most. Although I am currently growing a critical jack pheno experiencing the same thing with just its baby cotyledon leaves, could be inherent to the strain. Keep an eye on it and I would ease up on the strength of your water, you haven't fed it anything have you? what is your water temperature? I would also suggest in the future to allow your seedlings to show their first true leaves and a good amount of roots to be exposed through a rock wool cube in an incubation spot, if possible, and then transplant to hydro.

Not sure on water temperature, I'll have to pick up a thermometer that's waterproof to check it out.

She's on day 9 now, I didn't feed anything for the first 7 days. Just water set at ph 5.5. I set the ph low at 5.5 because it tended to drift upwards. I figured it would drift up more into that optimal range on its own after several hours.

At day 8, I gave her a 1/4 strength feeding. I have the "advanced" nutrients pack from GH. The first feeding included: CaliMagic, Rapid Start, Flora Duo A, Diamond Nectar. Not sure if you're familiar with those. It was part of a package I bought at a local hydro store to get myself off the ground.

That was just yesterday and she seems to be doing OK. The yellow tips came about long before the feeding, which is why I'm suspecting temps and/or my shitty tap water.

 

[Purple Haze]

Much appreciated! I've dug around and couldn't find anything specific to seedlings... I know they're sensitive (because I've managed to kill two of them already so far) so I want to make sure I fix this if its an issue.

I think my tap water might have been the problem too. I've been keeping a close eye on it and adjusting (I adjust it right in the bucket with General Hydroponics PH Down solution) as needed. But I think the high ppm coupled with a high initial ph (9.1) might have made it a little unstable.

I will post a pic of the seedling in a few.

Right there is your problem. Having a really high ph of 9.1 to bottom down to 5.5 is a drastic and sudden change that will sicken any plant. You have to use gradual adjustments of ph up and down and never more than once in a 24 hour period. Keep your water stable between 5.5 - 6.1 and keep your water temperature at 70 degrees or below. It is best to keep your Ph at the optimal levels BEFORE starting. Good luck sir!

 

[Eljefemoe]

A snippet from the web,,

Cold - Cold weather (below 50F/10C) can lock up phosphorous. Some
varieties, like equatorial sativas, don't take well to cold weather. If you can keep the roots warmer, the plant will be able to take cooler temps than it otherwise could.

hmmm interesting....
PH - The pH of water after adding any nutrients should be around 5.9-6.5 (in rockwool, 5.5-6.1). Generally speaking, the micro-nutrients (Fe, Zn, Mn, Cu) get locked out at a high pH (alkaline) above 7.0, while the major nutrients (N, P, K, Mg) can be less available in acidic soil or water (below 5.0). Tap water is often too alkaline.

Heres the link bro ;

https://www.greenpassion.org/OG-FAQ/58.htm

Thanks man, this is helpful. I knew the ph range I was shooting for, but I never actually knew why (lol). Good info, I'll give the link a read.