My outdoor plant has been growing for two months. The lower leaves are starting to become yellow and wilt. There are a few brown spots on the leaves. I have not added anything because I do not know which nutrients or supplements to buy for my plant. The upper leaves are green but I am afraid they will turn yellow too. The stems are strong and the roots are strong. I do not know if it is the soil or over watering? Please help I am totally lost..
from what I heard this is natural the first few leaves will fall off they did on mine and that was it the rest remained green you should be ok!
Pictures would be a big help. But it sounds like a nitrogen deficiency and being you have no been giving them fertilizer, if it's in a pot, I'd bet on nitrogen deficiency. You need to get fertilizer. Read around the forum, there's plenty of threads about good fertilizers.
this: http://forum.grasscity.com/sick-plants-problems/226015-when-posting-your-sick-plants-questions.html
i second banana, although all details of your grow woukd be helpful. Keep them gren and happy....foliage = flowers.