Definitely partial sun. Does great in shade here actually, but our sun is so strong. Are you inland or more toward SF? In SF they could probably handle more sun. They like really great drainage. The clay soil here needs to be amended so it drains better for gardenias to be happy, or they also can do well raised beds here.

Find your Sunset Climate Zone in the climate maps part of the Sunset Western Garden Book and then look up Gardenia in the plant encyclopedia section.

I have a gardenia in my backyard (here in Livermore) and it gets a few hours of sun in the morning and is in bright shade the rest of the day. As mentioned above, gardenias like fertile, acidic soil with good drainage. From what I have read, gardenias don't like their roots disturbed once they are established, so if you put it in a pot in the beginning and decide later on to plant it in the ground, take care not to disturb the root system. If you have a morning sun/afternoon shade spot in your yard, I would personally put it in the ground since you won't have to water it as frequently. Good luck!

I know somebody who told me that when he lived in Fremont Gardenia's did great..bloomed fine.

They are not drought tolerant though..water well,and mulch too. Acid fertilizers are good for them.

Any morning sun spot would be great! If you want to plant it now (rather than in the fall), I would run a hose out to the area you want to dig in and let is slowly trickle for a couple of hours. This will help saturate the soil and make it easier to dig in the spot you want to plant in. Once you have your hole dug out (twice the width/depth of the pot should be good), fill it with water and monitor how long it takes the water to drain out. If it drains quickly (within a few hours), drainage is good. If water stays in the hole overnight, drainage is bad and the soil will need to be amended. Either way, I usually mix the dirt I have taken from the hole with some kind of a good soil amendment/compost blend. I bought some as OSH or you could get it at a nursery in your area. Fill the hole with the amended soil and create a mound in the hole. Set the plant on top of the mound, making sure to place the plant slightly higher than the existing soil. Water your plant in deeply. Soil pH should be between 5 and 6. SFGate has some good articles on gardenias. Check out this link: http://homeguides.sfgate.com/gardenia-jasminoides-leaves-turning-yellow-66388.html