I have a small gardenia bush planted in a large plastic pot and the leaves are turning yellow.

Question

Also, the flowers are turning brownish soon after blooming. I live in the midwest and it's been hot so I water it every day/every other day.

Answer 1

It sounds like spider mites.  If you look real close at the plant...do you see little black specks?  it could also be white flies.  Use a  insecticidal spray.  But, the plant can be killed so quickly by this infestation.  You're plant is probably  already on it's way out.

Answer 2

STOP!!! you're overwatering it! Overwatering will cause leaves to turn yellow and drop off.

Move the plant into an area where it is shaded during the hottest part of the day; it will help the flowers. Don't water it until the top of the soil dries out and it no longer looks wet on top.

If the leaves are yellow but the veins are green, it would benefit from some iron.

Answer 3

If it is caused by insects, dump a pan of dish water on it. Not a lot of dish soap but enough to make a few suds. Also gardenias need a lot of water.