need to give my plant nitrogen.??

I have a plant that is about 2.5 ft tall and is in a pot with Miracle Grow potting soil. This is my first attempt so bear with me. I can tell by yellowing of lower leaves and redish stem that its probably Nitrogen deficient. Being that i am using M/G potting soil i am in a pickle. I now understand that its not the best soil to use but im trying to make due with what i got now. Any tips or ideas on how to get my plant healthy without burning it will be sooo appreciated. also i am growing outdoor on a serious budget so keep that in mind too.
thannk

Miracle Grow soil (3 month mix) is fine, once you get used to it. Same with any medium you'd choose.

What nutrients are you using now? (Miracle Grow soil will not feed her forever)

I havent given her any nutrients cause i was worried about nut burn due to the time released deal with M/G. shes a little over 3 months old though so maybe all the nutrients are sucked outta the soil and its ok to feed her something. whats your advise. I have miracle grow fertilizer. will that help?

Before you feed her I would give her a repot as well so the roots have got room to move and be able to suck up the new nutes you will be giving her............. ?