In a practical sense we are particularly interested in optimizing artemisinin yield irrespective of whether this be on a perplant or per-land area basis. One way to achieve this requires nitrogen optimization based on artemisinin yield per plant, and this can be calculated from the multiplication of leaf artemisinin concentration by leaf dry matter yield. From this the total yield of artemisinin, on a per-plant basis, increased with increasing nitrogen application up to 106 mg L21. Increasing nitrogen concentration application above 106 mg L21 did not increase artemisinin yield. At this concentration of nitrogen, the plant had a leaf nitrogen concentration of 5.5% (w/w) at the time of harvest, which was adequate for maximizing artemisinin yields.