There have been several alfalfa varieties that have been developed that have claimed that they could spread, run, or creep to thicken stands. These alfalfa plants grew underground and used rhizomes to form like bluegrass sod instead or growing in clumps like normal alfalfa.
Is this a good idea or not?
Producers could use this self-thickening alfalfa in a pasture or hay field which would improve the protein amount and feed value that would be grazed or baled for hay. If surrounding plants would die, the alfalfa plants could grow where the plants use to be. This could potentially create alfalfa fields that last forever!
Like anything to good to be true, these alfalfa varieties did not live up to all the hype they were getting. The plants were spreading to areas of bare ground, but how often is a field completely bare. There are always weeds and other plants that took up the space so the alfalfa wasn't able to grow quick enough before the weeds moved in first.
Are these varieties useless?
Personally I would not use these in a pasture because there are better varieties of alfalfa that have shown that they can produce more and have longer grazing periods. These select alfalfa varieties could be used in a long-term hay mixture in the hope that they will eventually spread to the bare areas.
Someday an alfalfa may come along that can thick its stands reliably. Until this happens better stick to the varieties that have proven to last.