Abstract: A method for enhancing the development of mycorrhizae in the root system of a plant. A quantity of a nutrient mixture is applied to the outside surfaces of the foliage of a plant rooted in a growth medium containing propagules of a fungus capable of mycorrhizal infection of the roots, the nutrient mixture containing a source of nitrogen and a source of at least one other element selected from among potassium, phosphorus, zinc, magnesium, boron, manganese, molybdenum, copper, and iron, in an aqueous vehicle. Such application is repeated at intervals over a period of time during which the supply of nutrients by fertilization is provided predominantly through such foliar application.