trimming yellow leaves

plants are about 4 weeks old, have/had some yellow lower leaves...I believe from under watering. increased water. some of the life came back. going to add a little blood meal for a nitro boost just in case the yellowing is from nitro deficiency. growing in fox farm ocean forest, and using earth juice, in peat pots. is it ok to trim back yellow leaves? and if so where do you make the cut? how much of an effect will the cold have on my plants? not very warm (65 degrees). growing under 4 24" T5 HO...no heat output. also have a incandescent 75w near by just to throw off some heat!

give the yellow leaves a small tug. if they resist then leave them attached to the plant

^^ what he said....or you can just let it do its thing naturally and when it doesn't need them anymore it will discard them on their own, people forget this plant has grown itself for thousands of years, sometimes we think too much