Are these underfed? Need help! (pics)

[Backpacker420]

These babies were doing so beautifully, and now they are wilting and yellowing. I've been careful not to overwater, and only fed them once with a mild solution of FF Grow Big. Have I been neglecting them? My water/soil runoff is roughly 6.8 or 6.9.

http://i28.tinypic.com/10dhyqh.jpg
http://i29.tinypic.com/2dhybtl.jpg
http://i27.tinypic.com/307t4k2.jpg

[stinkyattic]

Too early to feed. Wait until the 5th set of adult leaves is unfurling to start on a 1/4 strength grow fert.
Next time they need water, use plain tap water and water until it runs out the holes in the cup.