Need Help! Bottom leaves yellowing and dying off

[Hansbricks]

Hey guys, hopefully someone can help me out here. My plant is 40 days old today and about a week and a half ago I started noticing the bottom leaves turning yellow. See first pic


I thought this was from underfeeding since my first 3 feedings were only 1/8, 1/7, and 1/6 strength. So I did the next feeding at 1/4, and then the last 2 feedings have been at 1/2 strength plus 6-8ml/gal of cal/mag.

Here's a pic from today



I've lost several of the bottom leaves now and more continue to turn yellow. Not sure what to do now, still just looks like N def to me... should I try my next feeding at 3/4 strength or more? My pH meter is fucked so I don't have a way to check soil pH at the moment. For my regular plain watering's I've been adjusting pH to around 6.5 and I'm using AN's pH Perfects nutes so I haven't been checking pH for the feedings. (So I guess my soil pH could be off but seems unlikely)

Any help on what to do next would be appreciated, thanks.

 

[kaosangel22]

Looks like either fade or ph lock out. Look up the cabbage technique for ph testing may help you out.

 

[namvet25]

If your using PH perfect you shouldn't have to worry about PH.I would say you did the right thing by increasing the dosage of your nutes and cal-mag.Are you feeding flower nutes? Remove the yellow leaves and you should be fine.It takes 3 to 4 days for nutes to work.If your plants are big enough you could go 3/4 strength and see what happens.

 

[N.W.]

Hansbrick.... Is it only the bottom of the plant or is it creeping to the top now as well????... Cant tell from those pics..

Did you flush your plant before adding nutes and cal/mag????..

 

[Hansbricks]

If your using PH perfect you shouldn't have to worry about PH.I would say you did the right thing by increasing the dosage of your nutes and cal-mag.Are you feeding flower nutes? Remove the yellow leaves and you should be fine.It takes 3 to 4 days for nutes to work.If your plants are big enough you could go 3/4 strength and see what happens.

Hey nam, thanks for you input. I'm using the 3-part GMB pH perfect nutrients so there is no 'switchover' to the flower nutes. Yea I will probably just try feeding at 3/4 strength next time since I haven't really seen any signs of nute burn. Going to try and pick up a soil pH probe tomorrow anyway just to check where it's at.

 

[Hansbricks]

Hansbrick.... Is it only the bottom of the plant or is it creeping to the top now as well????... Cant tell from those pics..

Did you flush your plant before adding nutes and cal/mag????..

So far its just isolated to the bottom leaves but is starting to creep up... the top 3/4 of the plant looks perfect and the buds have been fattening up nicely still. I have not flushed my plant yet... my last 3 waterings have been with nutes since I thought I had been underfeeding, previously I was alternating feedings with just plain RO plus cal/mag.

 

[stric9]

Looks like lock out. What's your medium?

 

[Hansbricks]

Looks like lock out. What's your medium?

I'm using pro-mix organic... here's a link to my grow journal for additional info https://www.autoflower.org/f44/first-grow-northern-light-blue-26082.html