HELP! Leaves yellow and crispy

[CaptainCrusher]

New grower and need some help, leaves turning yellow with brown spots and crispy. Coco coir medium, autoflowers week 8, 4 x4 tent, 600 watt led, general hydroponics nutrients, I always ph my water.

 

[SoOrbudgal]

Hello you've got some nice big autos so don't dispare. I've had the same bothersome issue with 2 of my autos this entire grow also and chased it trying to fix now i'm at 10wks and don't give a hoot. I don't think i fixed it. I blamed it on the cool enviornment when lights were out, maybe roots got chilled and pots didn't dry quick. I did try adding some liquid fish&guano on one watering without using bloom nutes at same time. Suger leaf came in nice an green but those other sick leaf will just die no fix for it. There gonna come off, your may be a issue with Cal/Mag maybe needs more cause of coco coir? I mix my own soil with coir maybe mine was short on mag? I also gave 1 feed of epsom salts 1tbls per gallon of water. Are you letting them dry out between waterings? What ever it is it was taken up thru it's roots and did'nt like it as you know by seeing them. Wish i knew but if my next round does the same as this something either soil or watering nutes they may needed more of.

 

[CaptainCrusher]

Thanks, I have been watering every other day now. I nutrient feed every other watering and i use 1/2 tsp of Cal/Mag per gal. Not sure what to do.

 

[CaptainCrusher]

Any help would be appreciated, these autos looked great up till a couple of weeks ago, I really haven't changed anything I was doing. Think I'm getting pretty close to harvest with it being the 8th week. Don't want to screw it up now.....

 

[homegrown]

I'd say light burn/heat stress and some nutrient burn. Hard to say without more info. How close is your light? Whats the temps? You say you ph water-what is your ph target? Have you checked run-off water ph?

 

[OldManGrower]

I have never grown in coco so my input is limited. You should PH your solution after adding nutes and checking the ph of any runoff as well. I agree with SoOrbudgal about adding some cal mag or additional cal mag. Are you using nutes at full strength? Most of us use one half strength. This sure looks like a combination of PH, nutrient up take issues and light burn.

 

[SoOrbudgal]

Do they feel light when you pickup the containers? Maybe your under or over watering, do you have some run off out the bottoms?

 

[OldManGrower]

If you get everything back in balance right away, you may be able to salvage some of your harvest. After reviewing your pics again, you definitely have light burn, nute burn and most likely PH issues. Raise your lights or dim them, flush your plants with straight ph'd water and check your run off. If the PH is way high or low, flush again with PH'd water either noticeably higher or lower then your last runoff value to get to your proper number and with Cal-Mag, and half strength nutes. This is a Hail Mary but I have had positive results doing this. Water every third day or when the soil is dry about an inch deep.

 

[Bluey]

If those plants were healthy you'd be underwatering and under nuting them....but they are not in a good way and are definitely nuted and heat/light stressed..
follow the above advice, the buds may be saved. Aim for pH runoff around 6.5...I wouldn't let the coco dry out..keep it wet. I water 3 times a day and not getting any runoff...but lift your lights or dim..it's making everything worse

 

[CaptainCrusher]

Thanks for all the help, I'm still learning here.. So I gave a extra feeding of cal/mag at 4 ml a gal, n watered 1 gal per plant with at least 20 percent runoff. I always shoot for 6.2 ph and I have I have been really good about. Run off ph has been about 5.9 to 6.3 every time .Don't think it's a ph problem. I have been using this nutrient schedule I got form GWE for the General Hydroponics flora trio, I raised my light up 4 inches and I dimmed my light down one setting to 7( HLG Blackbird) ....Gonna roll with it a hopefully harvest in a week or so. Just gonna try to do better next time. Totally thought I had this all under control,,... lol. Thanks for all the help.

 

[Bluey]

I'd up your pH a bit..aim for 6 3 to 6.5pH run off...6.5 late flower might be fine