Alfalfa contains the hormone, Triacontanol, a plant growth regulator. The primary boost comes from the millions of microbes in the fermented meal that activate the soil organisms that then convert nutrients into forms available to plants.
It's carbohydrates and protein make it an excellent soil conditioner by encouraging microbial activity in the soil.
Alfalfa Meal is suitable as a soil amendment for use on roses and small shrubs. It can also be used to give rhododendrons and azaleas a boost after flowering.