Field research was conducted on Hyssop (Hyssopus officinalis L.) plants in the Mariout region, North of Egypt during the two successive seasons of 2020 and 2021. The purpose of the study is to determine the optimum space, chemical fertilization, and their interactions on the biomass yield. The research was set compatible to a split-plot design technique. The inter spacing was 30 and 50 cm, while the subplots had chemical fertilization at three levels: full dose NPK, 2/3 NPK, and 1/3 NPK. The used chemical fertilizers (full dose of NPK) were: 450 kg ammonium sulphate (20.5% N) + 300 kg calcium superphosphate (15.5% P₂O₅) + 150 kg potassium sulphate (48% K₂O)/feddan. The results of the two cuts revealed that cultivation at a narrow spacing of 30 cm and adding a full dose of NPK recorded the significant highest production of herb and essential oil yield in the total area. The extracted oil contained pinocamphone (31.61-57.63%) and α-pinene (20.47-49.88%) as principal compounds. Cultivation at 30 cm space and adding the full dose of NPK also improved the pinocamphone concentration in the essential oil better than other treatments.