Pure Live Seed

Pure live seed (PLS) is a measure used by the seed industry to describe the percentage of a quantity of seed that will germinate. PLS is obtained by multiplying the purity percentage by the percentage of total viable seed, then dividing by 100.

Purity is the percentage of seed by weight that is the labeled species; the rest of the material is inert, weed seed, or other crop seed. Total viable seed is the percentage of seed that will germinate (germination plus dormant). By multiplying these two factors together, one can determine the percentage of material that is actually pure live seed versus the percentage of materials that is essentially worthless.

PLS is a way to standardize quality so that the purchaser can compare the quality and value of different seed lots.

Consider the following example:

At first glance, Lot A might appear to be a better buy because it only cost $1.00 per bulk pound, whereas Lot B cost $1.50. However, the quality of Lot A is poorer than Lot B. In order to compare the value, one must calculate the cost per PLS pound. PLS cost is obtained by dividing the bulk cost by the % PLS:

In the above example, the cost of Lot A is $2.22 per PLS pound while the cost of Lot B is only $1.97 per PLS pound. Therefore, Lot B is a better value. Furthermore, since Lot B has a higher PLS percentage, it is not necessary to plant as much material as would be required if you were using Lot A, which may result in lower labor costs.