PLS is an acronym for pure live seed and is expressed as a percentage. It is the result of a calculation that takes into account the percentage purity of a given seed lot and the percentage viability of the seed in that lot. PLS-seed tests are performed on single species lots.
PLS % = % Purity x % Live Seed
Purity is the percentage of desirable seed in the lot sample. Any weed seed or chaff in the lot sample reduces the purity percentage. Weed seed can be noxious weed species as well as other native species. However, any seed species other than the target seed species is considered weed seed.
The live seed percentage combines three separate values: % germination + % hardness + % dormancy.
Therefore, PLS % = % purit y x (% germination + % hardness + % dormancy)
Reputable native plant nurseries use independent seed-testing laboratories to assay their seed lots and determine the PLS percentages of each of their species seed lots. JFNew Native Plant Nursery sends its seed lots to independent seed-testing laboratories.
