The third stage of immature oil palm is the phase where the plants enter preparation for flowering, so efforts are needed to initiate flowering, one of which is by using plant growth regulators (PGR) such as paclobutrazol. It is expected that the use of oil palm fronds as compost and application to oil palm plants can support sustainable oil palm management activities. Paclobutrazol, as a growth regulator, plays a role in stimulating the flowering of immature oil palm plants. This research aims to determine the response to the growth and development of immature oil palm plants in the third stage by administering palm frond compost and paclobutrazol at certain doses and concentrations. The experiment was carried out from June to December 2020 at the Ciparanje Experimental Garden, Faculty of Agriculture, Padjadjaran University. The experimental design used was a Randomized Block Design (RBD) with 12 treatments and three replications. The experimental results showed that the application of compost to oil palm fronds and paclobutrazol had a significant effect on plant height and stem girth, but there were no significant differences in the number of fronds, leaf area, chlorophyll index, and flowers. All treatments did not produce flower shoots but showed inhibition of vegetative growth in immature oil palm plants in the third stage. The application of 12.8 kg of oil palm frond compost and 150 ppm paclobutrazol had the best effect on the height and girth of the oil palm stem and had an effect that was not significantly different from other treatments on the parameters of a number of fronds, leaf area, leaf chlorophyll, and flower growth.