<section class="abstract"><p><em>Pelargonium tomentosum</em> Jacq.; the peppermint-scented pelargonium, is an herbaceous groundcover indigenous to the Western Cape of South Africa. Volatile oils are produced by this plant, which are used in the fragrance industry. Studies on other <em>Pelargonium</em> species have shown chlorophyll content may affect the yield of essential oils. This study was carried out to investigate the viability of growing <em>P. tomentosum</em> in deep water culture (DWC) hydroponics and how best to aerate/oxygenate the nutrient solution to increase the chlorophyll content within leaves. The experiment was conducted over a period of 74 days, 16 different methods of oxygenation were applied to 9 replicates. The control had passive aeration; the treatments were made up of air-pumps, vortex oxygenators, and the application of hydrogen peroxide at various frequency intervals; these were combined with each other and run as separate oxygenation methods. The measurement of the chlorophyll content…