Rhododendron obtusum (Lindl.) Planch. ‘Hinodegiri’ responded to the different fertilizer sources and application methods similarly regardless of growing media. Plants top-dressed with Osmocote 18N-3P-10K had a significantly higher growth index, larger stem caliper and increased fresh weight than plants top-dressed with Pro-Grow 24N-3P-10K. Incorporation of either fertilizer source resulted in reduced plant growth and quality. The best fertilization method was a surface application regardless of fertilizer source or media.