Tropical Hibiscus not blooming ... prune, feed, spray?

We have two tropical hibiscus each in their third growing season since we bought them in 1 gallon containers. The past two summers they have bloomed prolifically; this summer they are rarely blooming. Lots of lush, dark green foliage. I long ago repotted them. They get plenty of water, from an irrigation system. I have fed them w liquid Miracle Grow.
I see some white flies but no sign of serious damage.
Do I need to feed more?
Do I need to prune?
I welcome any advice.

Don, Columbia SC zone 8

How's your weather been? Mine tend to not bloom much when it's cloudy out or when it's too hot so if you've had a lot of cloudy/rainy weather or it's been super hot then that may not have been ideal blooming conditions. On the fertilizer--I'm not sure what the N/P/K numbers were on your Miracle Gro, but hibiscus don't like a lot of phosphorus so I'd avoid fertilizers with a high middle number. They should be pruned to maintain their shape and keep them from getting leggy, but pruning now will probably delay your flowers even further so if you've kept up on the pruning in the past and their shape is decent then you probably don't need to prune them right now.

Which Miracle-Gro did you use, if you used the bloom booster 10-52-10 type they will stop to bloom for you do to the high phosphorus content it has, you have to use the Miracle-Gro general purpose type 24-8-16 which is more like for hibiscus. Second, are they receiving enough direct sunlight, hibiscus need at least half day direct sunlight to induce blooming. Third you should fumigate maybe with some neem oil to get rid of the white flies, they might not be serious right now but they do suck out nutrients the plants need and if not put in check they can get out of hand pretty fast, they multiply very quickly by the thousands, any one else that has an opinion that could help Don get his hibs to bloom is appreciated very much.

Wilfred

BTW, do you have a photo of the plant you could post, it will help us to help you.

Liz, looks like were almost on the same track and you got the thing I've over looked, like weather conditions thanks Liz.

Wilfred

Hi. I live in Hawaii so Hibiscus grow pretty well. The cultivated ones need more attention.
There are many solutions that work well. I used Murphy'Oil last season and had pretty good control. You should rake under the plants as that is where he eggs are. You should spray often at first as it only keeps the insect from multiplying and when the cylce is over you should see improvement. I am not sure of the concetration of the Murh's Oil I just put some in the feeder and hooked it up. It is better to use a sprayer that is more forcefull then the sprayer that comes with fertilizers. Be sure you spray both sides if the leaves. I am not an expert at all. But this has worked for me. (Also talk to them and check them out frequently.