Trials with Moringa oleifera leaf extract (MLE) sprayed on leaves of wheat (Triticum aestivum L.) showed different outcomes in grain yield and the components of yield (biomass at anthesis, number of ears, number of tillers, grain weight, 1000 seed weight). An irrigated field trial testing different MLE concentrations resulted in an increase in grain yield of 19% with a 10% concentration but not significant yield increases for higher concentrations of MLE. Dryland field trials with MLE concentrations at 5% and 10% showed no effects or more moderate (about 5–10%) increases in grain yield, depending on the year and location of study. The differences in grain yield responses are most likely due to changes in phytohormone concentration in MLEs brought on by abiotic stress (moisture deficit and seasonal change) of the moringa tree before the collection of the leaves. Concentrations of gibberellins, auxin, abscisic acid, salicylic acid, and jasmonic acid in MLEs differ markedly due to plants subjected to abiotic stresses. Comparing chemical analysis of MLE with grain yield effects showed that GA4 – most likely in crosstalk with auxin – is the major growth enhancer. It is concluded that the hormonal concentrations of MLEs strongly varies on a yearly basis, which may affect the potential use of this bio-stimulant in agriculture.