Effects of Spent Mushroom Compost and <i>Sargassum</i> on Growth and Physiology of <i>Philodendron</i> ‘Prince of Orange’

Purpose: This study investigated the effects of different recycled organic wastes in the growing substrate on the growth and physiological traits of Philodendron erubescens var. ‘Prince of Orange’. Methods: The plant was cultivated in various substrates containing vermicompost, 6‐ and 12‐month‐old spent mushroom compost, and Sargassum algae, combined with perlite and cocopeat. Growth, biochemical, and mineral parameters were measured. Results: The substrate containing 29% perlite + 10% 12‐month‐old spent mushroom compost + 1% Sargassum algae + 60% cocopeat (T15) significantly outperformed other treatments, increasing root fresh weight by 50%, root volume by 79%, and leaf area by 223% compared to the control (30% perlite + 70% cocopeat). This treatment also exhibited the highest total chlorophyll content (7.01 mg/g FW) and relative leaf water content (81.18%). In contrast, the control substrate showed the highest total flavonoid content (77.90 mg/g DW) and antioxidant activity (91.46%). Mineral uptake peaked in the optimal substrate (T15), with 6.36 mg/g Ca and 0.60 mg/g Mg. Conclusion: The optimal substrate mix of 29% perlite + 10% 12‐month‐old spent mushroom compost + 1% Sargassum algae + 60% cocopeat is recommended for the cultivation of this indoor plant.