The conditions are good, but stop feeding as it does not need it and it can delay flowering. Just apply a high potash feed in spring for each of three springs.
I have a Cornus florida Rubra for 7 years and it has never flowered.It is sheltered, facing south and looks healthy, fed twice a year. Soil is neutral and I have Cornus Controversa Variegata growing successfully near by. Can you please help as I cannot wait to see these flowers.
Cornus florida needs sunny summer weather to build up flower buds for the following year, and this tree can be slow to flower, needing to make some size first.