Black leaf tips

[Cmoore2382]

What's going on everyone. I'm a first time grower new to the site. Wondering if I could get some advice. I measured my runoff and got an e.c. of 5.0 my ppm was 3800 and ph 6.4. I have no clue what's going on. Here's all my variables 1. Outdoor grow
Ro water
white widow fem seed ilgm
It's fem photo
Plant is 8 weeks from germination
soil is 50% happy frog 20%coco 10%ocean 10%hydroton
Black 7gal fabric pots
Ph and tds of source water is 0
I'm feeding with ff trio plus calmg recharge i feed half of recommended dosage. Ph at 6.3ish and ppm around 800 at this stage.
Temps in the day have been in the 90's and upper 70's at night.
Now I have these black leaf tips and yellowing of the lower fan leaves.
Thanks for the help.

 

[HempKat]

I'm not sure on what's causing the black tips, the only I wanted to comment on was the yellowing of the lower fan leaves, that's usually an indication of one of two things well one of three but your ph is good for soil so I don't think it's from a ph issue. The other two things is one, the plant has just gotten so bushy above that not enough light is getting to that lower leaf and so the plant has sucked what nutrients it could out of it and is letting it die off. This could be the case because it looks like the growth above is fairly thick and as far as your picture shows it's only one or two leaves this is happening to and that process is fairly normal. The bottom leaves are usually the first to go when the plants starts filling out. I can't be 100% certain though because the picture showing the leaf still on the plant is too focus on that leaf and so I can't see what may be above blocking the light to that leaf. The other thing it could be is the beginning of the plant becoming root bound if so again usually the lower leaves go first but if it's just one or two at the moment you're in the early stages if it is getting root bound so you don't have to transplant it to a bigger container just yet. If you see the leaves continue to yellow and die off in bigger numbers then you'll want to consider that but for now you can probably wait. I went back and looked at the tips again and I'm thinking that might be that the plant experienced a little nutrient burn recently? I'm not 100% sure though. Some of the other ones that weren't exactly black looked like slight nutrient burn but I don't recall ever noticing a plant that I knew was nutrient burn having black tips. Somewhere in this sub folder there should be information helping to diagnose common deficiencies. I looked on some documentation I have on my computer but nothing matched with what you are showing in your pictures but what I have is very limited too. Hopefully someone else will chime in with more definitive information?

 

[Creeperpark]

EC is 5.0 ppm was 3800 is normal for an organic mix. The black tips are caused from a chemical build-up in the soil. Don't use fertilizers when its hot weather outdoors. It may be time to stop nitrogen all together, depending on the photoperiod. Coast for while with pure "water only" and the plant should be ok, and when it gets cooler you can feed a little. Your plant is ok, but burnt tips are permanent.

 

[GMT]

Hempkat nailed it but I'd try to get those daytime temps down a little.

 

[Creeperpark]

When the temperatures are hot, plants use water to cool themselves, by means of transpiration. Water is transported from the roots through out the plant and out the stomata. The stomata allow water vapor and oxygen out of the leaf and carbon dioxide into the leaf. During hot temperatures the plants main focus is on staying alive by cooling itself with water transport. If they're is a lot of salt in the ground water, transpiration becomes more difficult. Because more salt is having to be transported, the salts can't escape as fast as needed for cooling needs and accumulates in the tips.