Bananas are fun! I grew up in San Jose and the people across the street had some: every year they would die down to the ground and then sprout new in the spring. They never did fruit, though, because dying down to the ground every year prevented the top from getting old enough to produce any fruit.
There are hardier varieties out, now. I have no idea if they would fruit in California, though.
All banana trees send out shoots from the base of the plant. People then can cut the shoot off and sell it or give it away and it makes a new banana tree. The hardiest is a variety called Basjoo, and while it will freeze down to the soil, every year it sends up a new shoot or two so the banana tree re-appears every year. I used to have one, and it is pretty cool to grow a banana in Kansas! Every year our temperatures go below -1 Fahrenheit so bananas are an ornamental for us, not a food producer.
Some varieties of bananas have seeds in the fruit and some do not. The edible varieties sold in the grocery stores are seedless, needless to say! If the seeds an be grown but they will need careful attention to temperature to do so: I have not yet had any success with seeds. If you would like to grow a banana I would suggest you buy a plant instead of seeds: it is easier!
Banana trees have easy to buy on line and they are not expensive at all: if you would like to try one why don't you order one and see if it does well for you? My old Basjoo used to do just fine when the air was dry, as long as I remembered to water it. Kansas gets more rain than California does, but even so I had to water it once a week if it did not rain.
This year I got a Mekong Giant banana plant: shipping was about $8 and the plant was about 3 feet high. It had just been split off of the parent plant the week before and it seems to be doing well on my back deck. I intend to winter it inside and then plant it where my old Basjoo was; my Basjoo had a power company truck parked on top of it and so it died. I cannot really complain: they needed to replace the old poles and they had paid us for the change in the right of way. It is a bit risky to plant another banana there, but if it lives I would hope to be able to divide the young shoots around the base and plant them in other places around the yard. Mekong Giant is a new variety and so nobody knows how hardy it is, yet, though some people perhaps 200 miles south of me were able to grow it in their back yard.