Ruth,
I have grown 3 of the 4 you mention and am wondering when you started them into growth. I have had Bridal Bouquet and Red Dragon blooming for a few weeks now. They were started in the first week of April. It seems all of the Asarinas I've grown tend to start blooming in mid to late summer and seem to get better as we move into fall.
Alana

I started my seeds around late march or early april also.
I started the seeds in the larger pots that I wanted to grow them in. A ton of the Bridal Bouquet came up and I just recently thinned them to 1 to 3 per pot. The others have 3 or more per pot, but not crowded. Should they have maybe 1 per pot?
Also I've just recently started using a little Super Bloom for them.

I have 3 per pot in 14" hanging baskets. They are in full sun in the am and have dappled shade in the pm.
Maybe they are just too hot to grow! I have a few plants that are suffering from heat exhaustion.