Selecting a persistent legume for a site can be frustrating. Gradually plant the legumes that performed well on more acreage until you have as much legume as needed. For a successful stand, the legume seed must be inoculated with the proper Rhizobium strain of bacteria. The bacteria actually scavenge the atmospheric nitrogen for the legume, and without bacterial colonization of the roots, the legume fails to thrive. The bacteria or inoculum are species specific, that is, the strain of bacteria that colonizes clover roots will not colonize alfalfa roots and vice versa.
Some bacteria are even specific within a species.
The effective bacteria for arrowleaf clover may not work as well on subterranean clover. An expiration date, indicating when the bacteria will be dead, appears on the preinoculated seed and on the packets of inoculum. If there is any doubt about the inoculum's condition, reinoculate the seed, even if it is preinoculated. Inoculating planted seed is difficult and usually unsuccessful. The syrup or sugar makes the seed sticky enough for the powdery inoculum to remain attached.