Hoya's are climbing houseplants used outdoors in mild climates. They have thick waxy, evergreen leaves and tight clusters of small flowers and are commonly grown in sunny windows.
A hoya plant does best in rich, loose, well-drained soil and blooms best when pot bound; they are usually grown in containers even outdoors. Do not prune out flowering wood; new blossom clusters appear from stumps of old ones.

With the right light, temperature, and watering, your hoya plants should thrive and give you the beautiful blooms you expect.