Does this appear to be a nitrogen deficiency? (photos attached!)

[mendoman]

First off, thanks in advance for your help!

This is a clone planted 29 days ago, and over the last couple of days the lower leaves are turning a uniform yellow. I'm using FoxFarm's Grow Big and Big Bloom at 50% strength. The strain is Blue Dragon and it's in a 5 gallon container until it gets too big, then I have a 10 gallon container that I will transfer it to.

Would upping my Grow Big help, or is there something else I should be doing? This is my first grow.

Here's the Blue Dragon:



My other two clones aren't suffering from the same malaise.

Here's the Grandaddy Purp planted 21 days ago (clone):



...and here's the Grapefruit Kush planted 20 days ago (clone):


Thanks again!

NOTE: The burned leaf tips was caused by watering with liquid nutes and the tips being in constant contact with the soil, which burned them.

[washedmothafuka]

Yes, it does look like a nitrogen defficiency because the larger leaves are turning yellow while the younger smaller leaves on your plant are still green. Although I noticed a few greyish spots on the leaves, this could mean there may as well be a potassium defficiency, or both potassium and nitrogen.

[MephistoX]

Check that PH first, to be sure its not lockout.

[mendoman]

So I got a nice PH tester and my Blue Dragon had a PH of 6.4, while the other 2 had a PH of 6.9.

Realizing that it was indeed a nitrogen deficiency, I went to my local hydroponics store and they recommended that I use my FoxFarms ferts as recommended (as opposed to halving the dose) and to sprinkle the soil with oyster shell.

I'll let you know how it turns out.

[mendoman]

One other question I had was about the part of the plant that was yellowing. The yellow leaves aren't dead, just yellow. Should they be removed or left alone?

[The Green Man]

Originally Posted by mendoman

One other question I had was about the part of the plant that was yellowing. The yellow leaves aren't dead, just yellow. Should they be removed or left alone?

Once they reach 50% damage or more take em off. If they aren't that bad leave them on.

Originally Posted by mendoman

I went to my local hydroponics store and they recommended that I use my FoxFarms ferts as recommended (as opposed to halving the dose) and to sprinkle the soil with oyster shell.

If its the first time giving them nutes I would start at a 1/4 strength of FF grow big. That stuff is really strong and will burn your young plants.