|We have 3 healthy, 12-year-old Nikko Blue hydrangea plants, approximately 12 years old in a shaded setting. They haven't bloomed in 6 years, regardless of how we prune them. and we're wondering why?|
|Nikko Blue is a type of Hydrangea macrophylla, and it actually prefers full sun or partial shade. Lack of sufficient sunlight is likely a contributing factor to your plants' poor flowering.
Another factor that might be affecting flowering is if the terminal buds that produce the next season's flowers are killed during the winter or pruned away. Perhaps your plants are in a cold pocket and would perform better in a location protected from winter wind and low-lying cold air.
As for pruning, these shrubs are best pruned in summer when the flowers have faded and new shoots are developing. Cut the flowering stems as low as practicable without removing the new shoots arising from them.
I hope these suggestions are helpful.