If I have mature Picea pungens glauca 'Hoopsi' that have produced cones for the last three years, how come there are no viable seeds? Is seed production from 'Hoopsi' possible? what factors could be contributing to the lack of viability?
Lack of a suitable pollen source. You need another tree (or trees) of the same species but a different cultivar nearby, to provide pollen for successful cross-pollination.
