Daisy is right on the heat and water. They are swamp plants. They are one of the last if not the last plant to break winter dormancy.
They are like ornamental sweet potato and periwinkle, they only like to take off when the soil starts staying around 70. Your daytime temp is in the 70s and night in the high 50's. I think if it gets warmer they all should bloom. Keep up the watering. Mine loved the heat in Texas but could not keep the soil moist enough. Maybe if you have not already mulched around them , I would also do that. May joy be at your doorstep!
