Abstrak. Penelitian ini bertujuan untuk mengetahui pengaruh komposisi media tanam dan konsentrasi giberelin serta ada tidaknya interaksi keduanaya terhadap pertumbuhan dan hasil bunga mawar (Rosa hybrida L.). Telah dilaksanakan penelitian di Dusun Sumber Rejo, Desa Sei Bamban Kecamatan Batang Serangan Nomor 25, Langkat - Sumatera Utara pada bulan April hingga Agustus 2019. Analisis data yang digunakan adalah Rancangan Acak Kelompok (RAK) pola faktorial 4 x 3 dengan 3 ulangan. Faktor pertama yang diteliti adalah komposisi media tanam (M) yang terdiri dari 4 taraf yaitu : M0 (tanah), M1 (tanah + pupuk kandang (1:1)), M2 (tanah + sekam (1:1)), M3 (tanah + pupuk kandang + sekam (1:1:1)) dan faktor kedua adalah konsentrasi giberelin yang terdiri dari 3 taraf yaitu : G0 (0 ppm), G1 (200 ppm), G2 (400 ppm) dan dilanjutkan dengan uji Beda Nyata Terkecil (BNT) pada taraf 5%. Hasil penelitian ini adalah media tanam berpengaruh nyata terhadap jumlah cabang umur 30 HST. Komposisi terbaik dijumpai pada perlakuan media tanah+pupuk kandang+sekam. Giberelin berpengaruh sangat nyata terhadap panjang cabang umur 30 HST, berpengaruh nyata terhadap jumlah cabang umur 30, 60 dan 90 HST, dan jumlah helai bunga. Konsentrasi terbaik untuk pertumbuhan mawar dijumpai pada konsentrasi giberelin 400 ppm. Terdapat interaksi yang nyata pada kombinasi perlakuan komposisi media tanam tanah + sekam dengan pemberian konsentrasi 200 ppm terhadap diameter bunga tanaman mawar. Kata Kunci: Mawar, Komposisi Media Tanam, Konsentrasi Giberelin. Abstract.This research aims to find out the influence of the growing media composition and gibbberelline concentration, and their interaction on the growth and yield of rose flower (Rosa hybrida L.). This research had been held at Sumber Rejo village, Sei Bamban, Batang Serangan number 25, Langkat - North Sumatera from March to August 2019. The design used in this study was factorial block randomized with 4x3 factorial pattern and three replications. Design are two factors studied, the first factor is the composition of the planting media (M) which consists of four levels, there were : M0 (soil), M1 (soil + manure (1:1)), M2 (soil + rice husk (1:1)), M3 (soil + manure + rice husk (1:1:1)) and the second factor is concentration of gibberellin that was consist of three levels, that were : G0 (0 ppm), G1 (200 ppm), G2 (400 ppm) and continued with Low Significant Different (LSD) at 5% level. The results of the study shows that the growing media affect significantly the number of branches at the age of 30 DAP. The best composition of the planting media was found in the treatment of soil media + manure + rice husk. Gibberelline concentration affected significantly of the number of branches at the age of 30, 60 and 90 DAP, length of the branches at 30 DAP and the number of flowers. The best concentration for the growth of Rose is 400 ppm an gibberelline concentration. There was interaction strands between the composition of growing media and gibberlline concentration on the diameter of flower on the rose plant on the combination treatment of composition of the soil + rice husk media by giving concentration of 200 ppm. Keywords: Rose, The composition of growing media, Gibberelline concentration.