Have a trumpet vine, for the zone 4 area. It was at another site for 4-5 years and given away because it never flowered. Now it has been 3 years and still not flowered. Has vigorous vine and foilage growth, no buds. Cut it down to the ground every fall. Fertilized it once with miracle grow when first transplanted 3 years ago, never since. In full sun. Any ideas to make it flower?