They may not be getting enough sun. Al

Mine bloomed the best with lots of water and fertilizer.

I guess it is too late now to start with more fertilizer. I had been giving them some 5-10-5. Still not results. Should I cut the foliage off this winter or leave it on?

My agapanthus are all in the ground and have never been fertilized. In a container they will need some fertilizer, but at this point I think withholding fertilizer would be more likely to cause a bloom response. In my climate they are evergreen and I never cut them back. They reseed themselves and those seedlings in the full sun are always the best bloomers. We occasionally get a winter in the teens and the foliage is frosted to the ground. It then takes a year to get back as before the frost. Agapanthus are quite capable in competing with root competition and flowering well without fertilizer, as long as they have sunshine. Al