Water scarcity is one of the major challenges facing the agricultural industry, necessitating the use of treated wastewater for irrigation purposes. However, not all crops can effectively utilize this water, as it may have negative effects on plant growth, including disruptions in nutrient uptake and photosynthesis. This study aimed to evaluate the effects of treated wastewater on the growth of rose-scented geranium (Pelargonium graveolens) and English lavender (Lavandula angustifolia). The experiment was conducted between 2022 and 2023 at the University of Fort Hare, Dikeni, South Africa. Two harvests were carried out in May 2023 (Harvest 1) and October 2023 (Harvest 2). Five irrigation treatments were applied to both geranium and lavender plants, consisting of treated wastewater from Dikeni town mixed with tap water at varying proportions: 0%, 25%, 50%, 75%, and 100% (v/v). Water and soil used were tested for nutritional composition. Treatments commenced four weeks after transplanting from cuttings, and the experiment followed a completely randomized block design with four replications across four blocks. The results showed no treatment differences in stem diameter, number of shoots, or plant height across treatments for both plant species during the two harvesting seasons. However, English lavender plants irrigated with 25% wastewater exhibited a slight increase in plant height at week 11, while geranium plants treated with 75% wastewater showed an increased plant height from week 5 until harvest at week 11. Additionally, plants receiving the 25% wastewater treatment produced the highest number of shoots from week 8 to week 11. These findings suggest that treated wastewater, both in its diluted and undiluted form, did not adversely affect plant growth. Therefore, it has the potential to serve as an alternative water and nutrients source for geranium and lavender plants, which farmers could utilize in collaboration with local municipalities to mitigate water scarcity challenges. However, further studies, particularly under open-field conditions, are needed to validate these results.
