The plant is in a 16" pot in a semi-shaded corner facing east. It is vigorously growing vine but no flowers for about a year.
Mandevilla – I Have a Large Vine With No Flowers. What Should I Do?
Certified GKH Gardening Expert
The plant might be getting too much nitrogen fertilizer. It may need phosphorus, which is responsible for blooming in plants. Try a high phosphorus fertilizer or add bone meal to the soil. Here is more information: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/phosphorus-plant-growth.htm
This article should help: https://www.gardeningknowhow.com/ornamental/vines/mandevilla/mandevilla-plant.htm