58:10 Incense is spices burned on coals to produce a pleasant fragrance. One recites the bracha after the smoke rises but before the fragrance reaches him. This is the same as we always do with brachos recited on pleasurable things (that the bracha comes before receiving the benefit). The blessing is not said before the smoke rises because the bracha should immediately precede the benefit. (If one said the bracha before the smoke rose or after the scent had already reached him, it is effective after the fact – Mishnah Brurah 216:46, 48.) If the incense comes from a tree, one recites “atzei besamim.” If it comes from herbs, “isvei vesamim.” If it comes from something else, “Borei minei besamim.” The bracha is only recited when one burns incense in order to enjoy its fragrance, not when it is used to cover up a bad smell.
58:11 Similarly, one does not say a bracha over anything that is not there specifically to enjoy its fragrance. This includes, for example, a storeroom full of spices for sale, or incense being used to perfume a garment so that the garment should smell nice. Even if one intends to enjoy these fragrances, he would not recite a bracha. (If one actively takes some of the spices in his hand in order to smell them, he would recite a bracha – Shaarei Tziyon 217:2.)