I would consider the possibility of fungus.

Are you re-using soil?
Are you sterilizing your pots between crops?
Do you have pests [vectors] that are spreading disease?
Are you over-watering and creating ideal conditions for fungus to thrive?
stinkyattic Reviewed by stinkyattic on . unusual plant problem Hey anybody out there, afriend of mine has been having a problem for a year now that none of us seem to be able to figure out. The plants seem to start out okay, but even in the vegetative stage the shade leaves will start to yellow just completely around the outer edges. Then above the yellow-edged leave it will revert and start putting out leaves again with 3 leaflets and then some leaves believe it or not with 4 leaves. The plants end up with a decent yield but look sickly the whole time. Rating: 5