Baja_Costero said:Put your plant in a heavy pot, or nest the container snugly inside something solid.
mcvansoest said:Agreed, but that could be from coolness, low light, and humidity. It should grow out of that.
From the gap between the soil and the pot there is a very good chance that most of the watering you do just washes straight through the pot. Time for a new pot with fresh soil.
Also keep in mind that these are predominantly night flowerers, the flowers open at night at stay open for a while (depending on heat and sun exposure) the next day.