Best is a ratio of 1-2-3, like 15-30-45. You probably will not find this! I buy Muriate of Potash, 0-0-60, and add some, guess work!! to the stuff like Vigoro.
You might need micro nutrients, look for Boron, Copper and Zinc. I haven't seen miracle grow with micros, yet.
Grown in peat, they have been under a greenhouse roof, so no rain, with highly controlled watering. One garden center here had their first lot of adeniums mostly die, rot, because the plants were outside on a table in the rain.
It's always good fun to find seed pods!! I spray my developing pods with a weak solution of fertilizer twice a week. Feed those guys.