Question: How can one tell the difference between Colorado blue and green spruces? Is there any way besides the color? Will aluminum sulfate change a green spruce to blue? LM, Wisconsin.
Answer: The Colorado spruce, Picea pungens, when grown from seeds produces all graduations of color from green to blue. Only a few will be definitely blue, and the color is the only distinguishing characteristic. Most blue spruces are horticultural varieties produced by grafting. The presence of aluminum sulfate in the soil will not change a green spruce to blue.
