I have both. To me, they are tough as weeds. Normal potting soil, a pinch of fertilizer, water and proper sunlight will keep them happy.
Osmanthus would develop massive root in pot in a few years.The best place to plant it is in the ground.

I do not care too much about the fragrance of M. figo. I gave it away last year.

Do you know if osmanthus will grow in South Florida? I seem to remember that it needs a colder climate/less humidty.

AnyaPerfurmer:

I will try my best to find out the information about suitable location for planting Os Fragrans. It may grow in south Florida. You might have to try it. Because Osmanthus is the Regional Flower for the region of Tainan, south of Taiwan. The area is very warm, no frost and very wet and humid.
Most popular and wild Os grow along Yangtze River. It has some snow and ice in Winter and hot in summer. Os will not stand the bitter cold. In Forbidden City and Summer Palace of Beijiang, There are about three hundreds of Osmanthus planted in large pots. They move the pots to the sheltered area during Winter time.

Kendra, plant them in pots slightly bigger than the rootball. Give them a couple of inches of soil to grow into but no more than that. Any good potting soil with good drainage will do.

Anya, yes, it will do fine in South Florida. I grow it here in the same Zone that you are in. Both are hardy in colder zones, but they don't need a cooler climate to thrive.