Black Hills Spruce (Picea glauca densata) growth rate?

Picea abies generally grow 12-16" per year in Michigan. The densata may be a tad slower, depending on what region it's growing in.

Trees are opportunistic, that is with ideal growing conditions they can grow an unlimited amount until the time to cease.......they have only a limited growth period per year...usually caused by sunlight and/or temperatures.

So an early warm spring, ideal carbohydrate load from the previous growing season, proper water and soil nutrients, plenty of sun....and the age of the plant.......juvenile stages they will grow more than old adult....will provide the most growth potential. In some areas it may be 4 inches, in others 14 inches. (though 14 would have me questioning excess nitrogen load).

If you are looking for a hedge, don't count your inches. Remember the plants are tightly packed and competition for nutrients great.