A 2015 report from Oregon Cannabis Connection cited by Hermann covers pollination studies and discusses unwanted pollination. “In three studies, pollen drift was observed across 5 to 12 kilometers (3 to 7.5 miles). A fourth study showed pollen drift for 48 kilometers (30 miles) across the Mediterranean Sea from Morocco to Spain, summarizes Hermann.
We don’t have sea winds carrying hemp pollen into Colorado, but it can be windy nonetheless. According to Hermann, a safe starting distance between marijuana and hemp plants is 10 miles. “There is no scientific backing to guarantee that distance, but it is a safe starting point.”