Benzelsanswered grow question 3 years ago The really bad ones, that look like they are dying back yeah, but if they just a bit yellow ish then leave em a bit longer. Plants do store nutes in leaves too, and as they die back the plant takes the nutes back and puts em to use, say into building buds. So I like to leave the leaves on as long as possible, but the second they look like they may be actually dying and at risk of picking up mold - I snip em off.