Q.Calotropis Procera and Calotropis Gigantea
The flower buds on my plants keep drying up. They receive about 11 hours of light daily. They are kept at temperatures of around 78 degrees at night. I use a humidifier, but now I’m wondering if they are too humid. Humidity stays around 65%. The buds are so pretty, but as soon as they open they dry up and fall.

Certified GKH Gardening Expert
It seems these plants grow in both humid and dry conditions in their natural habitats, so the humidity is probably ok. The light intensity indoors might be more of a problem- these plants typically grow outdoors, and indoor light is almost always lower than outdoors. You could try adding an additional grow light or finding a sunnier window.
Another possibility is that they are overwatered, which can cause flower buds to drop off many indoor plants. Make sure the soil is getting dry at the surface between waterings and that your containers and soil are well-drained.