My plants very healthy, but there are no flowers. What can I do to get flowers?

It depends on what kind of plants you have. If they're annuals, you should be getting flowers soon, as they tend to quickly bloom as long as the environment is right, then die. If you have perennial shrubs or forbs, there's a few possibilities: 1) You missed the window of opportunity, as some plants, like lilies and irises, only bloom once at a particular time of year; 2) The plant is still growing and not focused on reproduction; or 3) The plant species has flowers that are hard to notice. You didn't make any specification to what kind of plants you have, so it's hard to tell from here.