The presence of leaf-eating caterpillars is one of the most common concerns in oil palm fields. Besides the use of insecticides, the growth of beneficial plants such as T. subulata can assist in fighting caterpillar infestations. This is owing to the plant's capacity to generate nectar, which attracts predators such as leaf-eating caterpillars. The purpose of this research is to determine the effect of combining various types of compound fertilizers, namely NPK Mutiara 16-16-16, NPK Grower 15-09-20+TE, and Nitrophoska special 12-12-17 (+2+6) +TE, with modified growing medium consisting of rice husk ash and compost. The application of NPK Mutiara in combination with rice husk ash addition as a growing medium was shown to have the ability to accelerate the flowering age of T. subulata and to increase the root fresh weight. This is due to the fact that the incorporation of NPK Mutiara 16-16-16, in combination with the improvement plant roots, results in superior nutrient uptake and root penetration in comparison to the usage of NPK Grower or NPK Nitrophoska. In addition, when compared to soil+compost, the addition of rice husk ash to ultisol was able to increase the flower and root number by 48% and 38%, respectively.