I have been growing 4 plants for about 4 weeks and 3 look abosolutly fine and are very green with big leaves. One has got a couple of brown patches i wouldnt call them spots near the end of the two biggest leaves. I have also noticed that the new middle leaves are pretty yellow and not coming in well. This has only grew taller in the past week and no new leaves have appear, when many have on the other 3 plants. does anyone know what is a matter with my plant?????? please help
More details of your setup would help but check the PH and the nutrients of the bad plant and if they are not normal then you have your answer. If it is not either of these things then check for pests, primarily spider mites. They hide under the leaf and will turn leaves yellow and affect growth in the ways you describe.