An experiment was conducted in 2012 at Teaching and Research Farm of Adamawa State University, Mubi, which lies within Northern Guinea Savanah Zone of Nigeria to study the effects of foliar fertilizer (Boost-Extra) and NPK levels on vegetative growth performance of maize. A split-plot design was adopted for the study with two maize varieties, Oba-98 and TZSR-W in the main-plots and seven fertilizer levels in the sub-plots (T1 Control = 0:0:0 kg N,P2O5,K2O ha-1 + 0 l ha-1 Boost-Extra; T2 = 120:60:60 kg N,P2O5,K2O ha-1 + 6 lha-1 Boost-Extra; T3 = 90:45:45 kg N,P2O5,K2O ha-1 + 6 lha-1 Boost-Extra; T4 = 60:30:30 kg N,P2O5,K2O ha-1 + 6 lha-1 Boost-Extra; T5 = 30:15:15 kg N,P2O5,K2O ha-1 + 6 lha-1 Boost-Extra; T6 = 0:0:0 kg N,P2O5,K2O ha-1 + 6 lha-1 Boost-Extra; T7 = 120:60:60 kg N,P2O5,K2O ha-1 + 0 l ha-1 Boost-Extra) replicated three times. Observed parameters were subjected to ANOVA using SAS package at P < 0.05. Means separated using DMRT. The results of the study revealed application of 6 lha-1 Boost-Extra foliar fertilizer had no significant effects on maize growth characters. Maize plant height, crop vigour, stem girth, leaf area index, shoot dry-matter and crop growth rate increased with increasing rates of NPK up to 90:45:45 kg1 N,P2O5,K2O ha-1 + 6 lha-1 Boost-Extra. Further increase dose of N,P2O5,K2O ha-1 to 120:60:60 kg with or without 6 lha-1 Boost-Extra showed no significant effect on the maize growth parameters. The application of 6 lha-1 foliar Boost-Extra fertilizer produced vigorous plants against zero fertilized plants only at 3 weeks after sowing (WAS), when no fertilizer was applied. From the results of the study, application of foliar fertilizer (Boost- Extra) was found to be not economically viable. Soil applied NPK fertilizer was observed the best form to deliver fertilizer to maize, and application of 90:45:45 kg N,P2O5,K2O ha-1 + 6 lha-1 Boost-Extra was found adequately to support vegetative growth parameters of maize at 6, 9 and 12 WAS.
