A greenhouse experiment was conducted for 130 days to assess the effect of application of uncoated urea (UA) and 3,4-dimethylpyrazole phosphate–coated urea (UDMPP) on mineral nitrogen (N) content [ammonium (NH4 +)-N and nitrate (NO3 −)-N] in leachates and growing media. Charlotte rose plants grafted on Natal Briar were cultivated in four different media [soil, 100% burnt rice husks (100BRH), a mixture of 65% burnt rice husks and 35% coconut fiber (65BRH), and 100% coconut fiber (100CF)] and fertigated with UA or UDMPP at rate of 170 mg N·L−1. Results showed that fertilizer induced slight acidity in the leachate collected in all growing media. The use of DMPP diminished cumulative nitrate losses by ˜65 and ˜60%, in soil and coconut fiber leachates, respectively, as compared to the plots with UA. The UDMPP did not have any effect on nitrate losses in BRH media.