In Tustin your plant(s) should give you bananas every year.
Superthrive is not a fertilizer. Amend your soil with lots of compost. Manure is also very helpful.
A good fertilizer has 2 parts Nitrogen - 1 part Phosphorus - 3 parts Potassium, check out Fruit Fuel for example from our member Richard
Plants That Produce Awesome stuff and it is 16-8-24 NPK.
Mulching is also a good idea to retain the water in our Southern California climate.
Overall, welcome to bananas.org and with the above recommendations your plant should grow and produce fast for you in Tustin. Keep us all posted.