Well, CBD's are broken down cannabinoids. The same as CBN's. They are broken down forms of THC. These are considered less desirable compounds because of the "down and out" effect they give. However, many growers (and users) prefer the mellow and down feel. So, they allow the plants to break down the thc in order to create more CBD and CBN. The general rule is this: clear-THC, cloudy-CBD, amber-CBN. This refers to the individual trichrome color and what compound is primarily present. The best way to do what you want is to get a high thc strain and grow it out a little longer. Now before I get flamed for saying that the trichrome appearance dictates the thc/CBD/CBN percentage, allow me to be preemptive. Some strains naturally produce more CBD/CBN BEFORE the trichromes erect. It is believed that indica varities produce less thc and more CBD/CBN than a sativa. So, my advise stands- buy a high thc producer and let it go a little longer. May not be what you want to hear, but time is relevant.