Apparatus and methods are provided for introducing an alkane to a plant in order to stimulate the plant's growth. Any type of plant may be treated, including potted plants, shrubs, trees, lawns, agricultural crops and the like. In a preferred embodiment, the alkane comprises butane, but other compounds can be used, including methane, ethane and propane. The alkane may be combined with water or another liquid carrier, or plant growth-enhancing additives such as nutrients, insecticides and alkane-utilizing bacteria. To induce aerobic conditions, oxygen-containing gas such as air may be introduced along with the alkane or separately from the alkane. The introduction of alkane may enhance plant growth by increasing the indigenous microbial populations in soil, e.g. bacteria, fungi, protists, and prokaryotes, which may provide benefits such as increased nutrient uptake, faster root development, and reduced heat, drought and cold stress, resulting in enhanced plant growth.