As soon as you complete his Perfecting Potions quest, Magnus gives you this, the Making Scents quest. A three-part questline, it introduces the bed of Wild Roses, among other sweetly-scented items.
Once you complete this quest, Magnus continues your scent-making training with his On the Scent quest.
Part 1 of 3
Part 2 of 3
Part 3 of 3