This research aims to determine the effect of trichocompost application on phosphorus (P) levelsinrosella(Hibiscussabdariffa)flowerpetalsplantedinultisolsoilanddeterminethebest dose that supports growth and flower production. The research was carried out in June– September2024attheAnimalHusbandryLecturer'sExperimentalField,Banjarbaru,withsoil analysisattheLaboratoryoftheBanjarbaruCenterforStandardizationandIndustrialServices and the Agroecotechnology Laboratory of Lambung Mangkurat University. The research design used a one-factor Randomized Block Design (RAK) with four trichocompost dosage levels,namely20t/ha,25t/ha,30t/ha,and35t/ha,eachrepeatedsixtimessothattherewere 24 experimental units. The results showed that the application of trichocompost had a significanteffectontheefficiencyofPuptakeandthe productionofrosellaflower petals.The doseof30t/haproducedthehighestabsorptionefficiencyof51.2%,whilethe doseof20t/ha and25t/hawasonlyaround13–14%,andthedoseof35t/hadecreasedto27.4%.Thehighest petal dry weight was also obtained at a dose of 30 t/ha of 4.94 g/sample, higher than 20 t/ha (0.67 g), 25 t/ha (1.15 g), and 35 t/ha (3.96 g). Thus, a dose of 30 t/ha is the most optimal condition in increasing P availability and rosella biomass production in ultisol soil.