Here in southeastern Iowa, the success of the blue spruce depends upon your expectations. For their first two decades, the trees keep their color well and form the snow-shedding dense pyramid you expect of a western mountain tree. It is a good wildlife tree — mourning doves like to nest inside the outer canopy — and the lower skirt of branches spreads out on the ground and provides year-round cover for rabbits and quail. If you are into dramatic and bold landscaping, this species will help you get there — for a while.
But after about two decades a little flaw begins to appear. Some sort of blight causes the older inner needles to fall prematurely and you begin noticing little gaps in the canopy.
Locally, when I’ve noticed that a failing Colorado blue spruce has been cut down, I’ll stop and count the growth rings. I don’t remember counting more than about thirty. In the wild dry western mountains, this species can grow a hundred feet tall and live for hundreds of years. But if that’s your expectation here in humid southeastern Iowa, you will be disappointed.
The evidence indicates that summer humidity and stagnant air is behind the early failure of the species. If grown where one side is close to another tree or tall bushes or a building, that is where the blight will begin. If grown more in the open, with good access to sunshine and breezes, the blight begins on the north side and then slowly spreads to the rest of the tree. The top, exposed to the best breezes and the most sun, often remains in good condition, while the rest of the tree below is slowly failing. There are a few large specimen around here which are growing in very open breezy spaces, but I do not know their age.
So I suggest that you adjust your expectations if Colorado blue spruce is part of your landscaping plans, and avoid disappointment later.