How big the pot is? If it is too big compared with the root ball, the extra water or moisture will cause root rot (damage the root).
If it is the case, at once repot the tree with a smaller pot (just about 1" wider than the root ball. Same as the depth, put about 1" soi. It is the key to the tree like osmanthus.

When you repot it, carefully cut the dead roots away. Dead roots are brown to black. Alive ones are white. Let the alive roots directly contact to the soil.

Soil mix: add about 1/3 of the sand (Home Depot, Play Sand) into the poting mix.

Throughout water it. Then leave it alone. Don't give it too much water. The sick tree needs much less water than normal ones.

After repoting put it where there is no direct light (I maen light, not sun. Young Osmanthus dose not like sun at all). Then gradually move to light, stronger light.

No fertilizer when the tree is sick.

Hope it helpful.

By the way, Osmanthus is outdoor plant.
Keeping it indoor may not good for it.

Dear wliu7, Thanks so much for your detailed and excellent advice. I will repot as you suggested, checking the roots for rot and adding sand to the soil. Unfortunately, I live in an apartment and cannot put the plant outside. Do you have any tips for helping it survive in a bright northwest light? Thanks again, Paula

I have experience killing Osmanthus, unfortunately. wliu's advice is great. After killing my first one I got two more, made sure not to give them too big a pot and added lots of perlite to the mix. Unfortunately one got too much sun and got a little scorched but that was a few weeks ago and it looks OK, still living anyway. :) The issue is DRAINAGE!!

TO: grwleye - Thanks for your help - perlite is a good idea - I went looking for sand today and could only find it in large quantities so the alternative is welcome!

Paula-I have no experince for keeping Osmanthus indoor. I would suggest that you put it close to the window or the place with GOOD ventilation.

No sun light. Less water and less water.

My Osmanthus Fragrans is sick also.If this one dies will be the second one I have killed! I did repot it and in a larger pot as it's roots were comming out of the original pot. I will try repoting in a smaller pot and pray that it makes it,I wrote down the details and am going to repot now,
thanks
Mari

I could not keep an osmanthus going in the house either.
When I finally got a tiny attached greenhouse, the humidity was up and the temperature moderated. I have one going and it has no problems. It goes out for the summer.

If you have an osmanthus *indoors* during heating season, it will require *much* higher humidity, good ventilation, a sunny window and *much lower* temperature than people prefer.

The same goes for Jasmine Sambac....

It might be that you have to think of a different plant that will tolerate your indoor conditions.

Good luck!
Maryanne in WMass

I am very much so starting to grow a few Osmanthus cultivars last year. I read the reference book from China. Do not water much during the Winter. Root problem tends to cause dropping the leaves. They do need proper light to stimulate new growth.