Screen house experiments were carried out to examine the effects of aqueous leaf extracts of Tithonia diversifolia (Ti) and Vernonia amygdalina (Ve), as well as NPK fertilizer (15-15-15) on the germination, growth and development of maize. Fresh leaves were collected, washed with tap water, chopped and pounded, soaked in distilled water and filtered. The two filtrates were used to prepare extracts at 50 and 100% w/v. Four maize seeds were placed in Petri dishes laid out in a completely randomized design with five replicates. In every Petri dish 10 ml of extract per treatment was added. A control experiment with distilled water was also set up. Also, in a completely randomized design with four replicates, 4-week-old potted maize plants were treated with 500 ml of each extract as well as with 1.52 g of NPK fertilizer. The results showed that the germination percentage of the seeds followed the order Ti₅₀ - Control - Ve₅₀. The seeds treated with aqueous extracts of T. diversifolia and V. amygdalina at100% w/v produced lower but equal germination percentage. The seedling radicle growth was significantly inhibited by the aqueous extracts of Ti₁₀₀, Ve₅₀ and Ve₁₀₀ (p≤0.05). The inhibition was dose-dependent and more pronounced in seeds treated with extracts of V. amygdalina. The aqueous extract of T. diversifolia (50% w/v) and control influenced radicle growth substantially. All the extracts inhibited the plumule development compared to the control. On the other hand, growth, development and yield were not significantly affected by the plant extracts.