Beginner Gardening: Ruellia not blooming!, 1 by jaclyn1

jaclyn1 wrote:
Hey!!! I'm so glad I found this post! I moved into my home 5 years ago and inherited 2 beautiful patches of Ruellia/Mexican Petunias. They grow as high as our 6 foot fence and I have easily managed to keep them from becoming invasive. I love them! My only problem is the first 2 years they bloomed prefusely from growth starting at 8" all the way up to 6'. Year 3 I started to get fewer blooms, last year they didn't start blooming until they were 4' and very few blooms...this year I've only had like 2 flowers on a 4' crop of at least 100. There has been no new conditions other than me trying to figure out what the problem is. There is adequate light, soil and water. The plants appear to be absolutly healthy. I can not find any appearance of pests or disease. I've tried fertilizing/not fertilizing, watering more/letting them go to wilt, compost...whats the deal?
I live in Augusta, Ga. and have seen my same exact plants blooming out of all sorts of soil conditions in southern Florida and I get so mad every time I do, because mine wont bloom. I hate to have to try to dig these out next year to replace with some thing else, because they are in a retaining wall surrounding my back yard and will be very difficult to remove the tough roots. Need help...rather keep them! Ruellia is in photo attaached in retaining wall. Thank you!!! Any help appreciated!