The number one cause of plants not blooming is insufficient sunlight.
The number one treatment the average gardener applies to get plants to bloom is adding fertilizer.
Can you see the conflict?
If a plant you grow is not blooming, or not blooming as much as you want, the first thing to do is to cut out some overhanging branches or remove dense vegetation around it so its leaves receive more light. Better yet, move it to a sunnier spot. Sunlight is energy and stimulates flowering.
What about fertilizer then?
If there is a lack of minerals in the soil, fertilizer may help stimulate bloom … but only if the plant is getting the right light.
So, gardeners, get your priorities in order. Improve the lighting conditions first, then if you think the plant could bloom better, you could try adding fertilizer. But start with light!
Some rhododendrons get slight foliar burn if they get enough sunlight to bloom to their full potential. On the farm, we grew a few cultivars out in the open, but with retractable saran to pull over them on the warmest days. It was a hassle, but made the plants more marketable, with abundant buds, and no foliar burn. Some of the cymbidiums that bloom best have slightly damaged foliage from getting all the sunlight they want; and they do not even need all that much.