Establishing fruit orchards with well-branched nursery trees is critical for early, high-quality, and consistent fruit output. The methods for creating branched young plants (chemical and physical) are typically expensive and/or inefficient. This study examined the effects of plastic mulch application in combination with promalin on lateral branching, branch/plant characteristics, and nursery tree quality in two sweet cherry cultivars: 0900Z and Sweet Heart (SH). The application of promalin enhanced the quantity and length of lateral branches, as well as the Fruit Sapling Quality Index (FSQI) in both cultivars. Plastic mulches increased almost all parameters compared to the absence of mulch. Notably, the combination of mulch and promalin resulted in considerable improvements in branching and biomass characteristics. Furthermore, this study formulated a new index called the FSQI (based on branching features and the Dickson Quality Index 'DQI') that can be utilized for fruit sapling quality classification. A substantial difference was found between FSQI and DQI in treatments where branch numbers increased with mulch and promalin application. This study demonstrated that mulch application can improve lateral branch production in sweet cherry nursery trees, and that young fruiting plants quality can be assessed using FSQI or equivalent indices that consider lateral branch characteristics.