Yellowing leaf tips and clawing!

[Autofems]

Hey all.
I have 3 autos on the go there 18 days old. All was going well until my strongest girl started to grow clawed leaves with some yellow tips. It's only on her new leaves older leaves haven't changed and are still looking ok.
It all points to a ph problem or nitrogen toxic from what I have read. I don't see how it can be either of those as I'm using biobizz light mix soil which is ment to regulate ph to within the 6 range and it is a light mix so has very little nutrients in the soil to start with so how can it be to much nitrogen.
I started biobizz grow nutes this week with a half dosage of 0.5 but these symptoms were there before the first nute. I tested ph run off water on one of the other plants and it was in the 6 range. Im really stuck on this one so any help would be appreciated

 

[Padawan1972]

I tagged @Waira for you...hes the guru for this kinda stuff.

 

[Autofems]

Thank you

 

[chefdave]

Hi Autofems. I am new also to autoflowers, but have many years of growing photos. I just had identical problem for 2 days on my plants. I also am growing with a 600 hps 6 plants. Do you have a ppm meter. If not get one. Flush with ph plain water till 20 percent runoff and test ppm of runoff, Mine was a slight nitrogen burn. I tried to push my plants to 800 ppm. I found all plants but one could not handle it. Also be careful not to overwater, so roots can have max nutrient uptake. Hope this helps. When you feed try 450 ppm with size of your plants now and work your way up. Cheers Chef Dave

 

[Autofems]

Hi Autofems. I am new also to autoflowers, but have many years of growing photos. I just had identical problem for 2 days on my plants. I also am growing with a 600 hps 6 plants. Do you have a ppm meter. If not get one. Flush with ph plain water till 20 percent runoff and test ppm of runoff, Mine was a slight nitrogen burn. I tried to push my plants to 800 ppm. I found all plants but one could not handle it. Also be careful not to overwater, so roots can have max nutrient uptake. Hope this helps. When you feed try 450 ppm with size of your plants now and work your way up. Cheers Chef Dave

Hey chef Dave.
So you think it's nitrogen burn. I didn't see how it could be that coz I haven't used nutes at all but I now think a bad watering pattern in the start has set me up for this. I'm going to try flushing and see how they go

 

[chefdave]

Like I said Autofems, I'm also new to autoflowers, They are great in many ways, but also from my short time of 35 days on my grow, very nutrient sensitive, and watering, humidity ph and temp. I have always grown in coco, so soil is not my cup of tea. Your plants still are healthy. Mine looked identical to your issue. I just did a mini flush tested runoff til 500ppm and within 2 days plants were back to fast growth. cheers chef

 

[Rudra]

Here is a nitrogen excess , your soil has some nutes in it for +- 10-15 days...Use only water some days.When you will see some improvement start feeding with light dosage , something from 250-300ppm and if all is good increase gradually ppm.
Sorry my english bad.
Good luck.

 

[Autofems]

@chefdave ok so I bought a ppm meter should be here soon and I will follow your advice. I'll report back in few days time.

 

[Autofems]

Here is a nitrogen excess , your soil has some nutes in it for +- 10-15 days...Use only water some days.When you will see some improvement start feeding with light dosage , something from 250-300ppm and if all is good increase gradually ppm.
Sorry my english bad.
Good luck.

Thank you I was confused as to where all that excess nitrogen had come from seen as I hadn't used nutes yet. But small plant in 10l pots that's alot of nitrogen plus I had heat issues in the begining which would make them drink more absorbing even more nitrogen then they could handle

 

[chefdave]

@Autofems Good morning, glad your getting a ppm/ec meter. Just wanted to remind you to check your ppm of your tap water if that's what you are using. 200ppm or below is acceptable. Mix nutrients to 400-450ppm and let sit 24-36 hours. Then check ph and ppm again right before feeding. Ph can fluctuate after sitting. Next grow try coco and perlite mix if you are comfortable. I use 80/20 mix coco to perlite. Great stuff. My first grow 10 years ago was with soil. My second grow was coco, I have never turned back. Have a great day Chef