How's your weather been? Blue Oat Grass is a cool season grass and requires a cool moist spring to flower fully. If it's been hot and humid, it won't flower well.

In my opinion, the foliage form and color is the showy part of this grass.

Expensive? Hopefully you didn't pay more than 7 dollars for the plant.... Blue Oat grass is grown more for the foliage, not the inflorescence. In terms of cultivation, the weather, noted by Donn, is part of the culprit. Second, what kind of soil, watering schedule, and fertility is the plant receiving?? The intensity of the foliage color and flower production is held with cool weather, low-fertile soil, and moderate to little watering. My advice is to selects another ornamental grass for the plume selection, and grow the blue oat grass as a knee-high texture plant.