They look like they are in the shade, and they love HOT sun! The more sun, the better the blooms and the richer the color! I don't even give them a thought because they grow easily here in the hot desert of southern California. Not sure how much water they even need, but yours look so lush and green. Our leaves look pretty beat up and ratty, but the flowers are gorgeous! They seem to thrive on neglect here. Maybe you are watering too much? Hopefully someone in your zone has the answer for your zone.
Suzi

Yup, too much shade, too rich of growing conditions (water, fertilizer) makes them wimpy and pale flowers. I saw this in the greenhouse I worked with every year when it got hot in the summer and they pulled 50% shade cloth over the greenhouses and had to water at least once a day because it was so hot. The flowers would "pale out".

More sun, somewhat less water.

I totally agree with the comments of the above posters. I know it goes contrary to commowisents, BUT, it's completely true these plants need and respond best to some tough love. Mine, do basically nothing but grow foliage in the summer when my plants are outside and everything gets hosed down or rained on every day. Then comes the winter and I bring them to work. They get searing morning sun through the floor to ceiling windows and I usually forget to ever water them. They are in full bloom in January when coworkers drop in to inquire what kind of plant it is. They love full sun, heat and occasional, severe drought to trigger blooming. Also, do NOT fertilize. If you tend to like to pamper your plants, this is not the plant for you.

Anyone know why there are so many multiple postings after a single submission? This is getting ridiculous!