They are small tubes, and at dusk, they draw the sphinx moths who know a good thing when they smell it. After dark, we partake of what the moth enjoyed earlier, a powerful fragrance that smells like nothing else. It can be noticed over several back yards. In fact, one night when it was large and un-macheted, I had to leave the lanai, as my eyes started to burn. I suggest planting it farther away from the house, but I do recommend it.
Guests are always impressed.
Whack it back after it blooms. Several times a year. A lotta bang for the buck. For a jasmine bush that needs little shaping, but creates lovely dignified flowers, on an orderly plant, try Tabernaemontana divaricata . Much easier to grow than a gardenia, its fragrance is gentle and increases at night.