Possible potassium or magnesium deficiency ?

So I have two plants in veg. 24 days old. Went from 16/8 to 18/6 a week ago (under a single 65W 6400K cfl). I water them when the soil gets dry, they're in plastic 7 oz cups. Not using any nutes. Couple days ago I noticed yellowing of the pre leaves, now their tips are dark brown, pointing downwards and the rest of the leaves is yellow. It's even starting to affect the first set of true leaves. I believe this is either a potassium or a magnesium deficiency. The stem is quite stretched cause I kept the cfl like 6" away for the first week.
I'll post pics once I find my usb cable.
I'll give them some nutes anyway, and can I give them some magnesium oxide ? Will they absorb it ? and how much ? (We don't have epsom salts here...)

No.,. Unless you planted it in sand, you are too young in to be having either of those deficiencies.

Check your PH.. pictures? If you haven't used any nutes yet, she is perhaps telling you how hungry she is.. use a light dose of all purpose and watch her go me thinks.

EDIT.. oh, and your 'pre leves' will turn hard and fall off..

Yea its probly nitrogen at tht age an mayb root bound but i cld be rong

Oh so those leaves are supposed to fall off ?

The little round 'pre leaves'.. they should of been gone already.. you probably took too good of care of them and they tried to stick around extra,.

haha thanks and I hope so!

Voila

Looks good.. those stems are just perfect to tie that sucker over and let her start growing from the sides.. Just one thought.

It looks like a N def. Transplant them soon, and start a light feeding schedule. Like 333maxwell stated, they are to young to be cal/mag def. Peace

I actually don't wanna do lst or anything, ima just let them grow so I can take clones and put them clones in flower. I hope I get at least one hoe. I think I might germinate more seeds...

juanhio said:

Voila View attachment 2822846View attachment 2822847

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Them plants are fine, the leaves that are yellowing are called cotyledons, and they should yellow and fall off shortly after popping from the soil. It looks like its time for a transplant into a bigger pot, on your next watering start feeding mild nutes, like 1/4 dosage and work your way up every feeding. Maybe even top now if you plan on doing that.

Thanks guys, I will transplant them tomorrow and put some nutes in.