The use of compost produced from plant waste as a growing medium in cut lisianthus and stock cultivation

Peat is one of the most common components of soilless growing media in cut flower cultivation. However, due to ecological sustainability concerns and rising costs, there is a growing need for alternative, environmentally friendly, and cost-effective growing media components. On the other hand, a significant portion of plant waste from institutional kitchens and similar sources creates an environmental burden during disposal processes. At this point, composting and the reuse of plant waste have strategic potential as solutions for both waste management and reducing growing medium inputs in the ornamental plant sector. However, the limited research on determining the appropriate compost mixture ratios for cut flower species represents a significant research gap. In this study, the potential of compost produced from plant waste to reduce peat moss usage in the cultivation of cut lisianthus and stock was evaluated in a pot culture experiment. The growing medium was prepared as a 2:1 peat moss: perlite mixture; compost was added at rates of 10%, 20%, 40%, 60%, and 80%. While no significant differences were observed in certain characteristics of lisianthus, such as plant height and stem diameter, the number of leaves and plant fresh weight were significantly affected by the compost ratio; low ratios (10–20%) generally yielded more favorable results, while high ratios (40–80%) resulted in a decrease in foliage and biomass. In lisianthus, increasing the compost ratio significantly reduced plant height, leaf number, and plant weight, and vase life declined significantly, especially at high compost levels; the best performance was achieved with 10–20% compost treatment. In conclusion, adding compost produced from plant waste at low rates (10–20%) to the peat+perlite mixture is an environmentally friendly option that reduces peat use while maintaining cultivation performance. However, compost rates of 40% and above tended to limit growth and quality parameters in both species.