Agrotechnological procedures related to forest management, including planting, are burdensome and the energy expenditure of the people working is very high. Nowadays, planting is usually carried out manually, and sometimes with the use of planters coupled to universal tractors. Occasionally, planters mounted on high-power carriers are used, and usually the seedlings are removed from their cassettes and placed manually into the planter’s storage unit. In connection with the above, the prototype of a mobile automatic device for performing forest regeneration tasks and afforestation of post-agricultural and reclaimed areas (RoboFoR) was designed. The main task of this vehicle is planting forest tree seedlings with a covered root system, which are collected directly from their nursery cassettes. This study presents the structure, principle of operation and results of operational tests of the seedling storage and feeding unit. It was found that the unit achieved the expected work efficiency. However, imperfections in the system related to the non-centralized distribution of seedlings in containers and the high variability of biometric characteristics of the seedlings were also identified. A new solution for this unit was proposed, which will increase the reliability of collecting the seedlings. A new solution requires greater computational power of the control unit as well as equipping the sensor system with a technologically advanced root neck detection system. The new concept also assumes the possibility of independent movement of each gripper.