Q: Can I prune a blue spruce to control its growth?
I have one near my home which probably was pretty when it was small, but is is growing taller and looks out of place.
The ideal time to do this is in spring, right after the "candle" has grown (this is what the new growth looks like before the needles unfold from it).
Remove 1/3, but no more than 1/2, of the length of the candle. This will reduce the tree's growth but still allow it to grow a little every year.
This will also help keep it fuller-looking for a longer period of time. It's a time-consuming task, as there are many candles on even small spruces, so be prepared to spend some time on it. I would use a good pair of scissors-type hand pruners, to make nice clean cuts.