If you take a look at recent posts on jasmines, you'll find a couple of discussions on poet's jasmine, or jasminum polyanthum; a google search will also get you good info. Basically, it needs night time temps in the 50s or 40s for a couple of months, and drier conditions, to set buds.

Star jasmine, assuming you're talking about jasminum nitidum and not trachelospermum jasminoides, which isn't usually grown indoors, you might try pruning back some of the stems to encourage new growth and buds, but keep in mind jasmines need a lot of light indoors to bloom well, especially in northern latitudes.

Hope this helps!

Jim

I am not sure about forcing them to bloom in the winter..never tried it!

See if these sites help you with their blooming time..

Click here..Poet's Jasmine
Click here..Star Jasmine

You might doubt my opinion, but I have had very good luck in playing classical music, actually the andante cantabile, for my one jasmine. It might be a coincidence

The best way to encourage a jasmine to bloom is to increase the light and the warmth at night. Increase the light, definitely.

^ agreed with the light and heat suggestion. We had 2 very sunny and warm days last week and my plants just took off.. (but now we're back to cloudy days again : \ .. )