Bulk vs. Pure Live Seed (PLS)
Ernst Conservation Seeds conditions and prepares seed to the highest standard and sells it in bulk or pure live seed (PLS) quantities. PLS refers to the amount of live, viable seed in a lot of bulk seed. In other words, it indicates the amount of seed in the lot that is capable of developing into seedlings. Often, “bargain” bulk seed with a low PLS percentage will end up costing more to appropriately seed a project than a higher priced bulk seed with a higher PLS percentage.
All seed suppliers are required to include certain information on the tag relative to the quality of the seed. Two of the most important items are the purity (or percent of pure seed) and the percent germination.
How To Calculate PLS
(PURITY x PERCENT TOTAL GERMINATION) / 100 = % PLS
Percent Total Germination =
[Germination + Hard seed + Dormant]
(90 x [78 + 10 + 2]) / 100 = 81% PLS
A seed label indicates 90% purity, 78% germination, 10% hard seed and 2% dormancy. See formula calculated above.
How to Determine How Much Seed to Plant
Divide 100 by the percentage PLS (In the example above, it’s 81).
(100 / 81) = 1.2 pounds of seed
Therefore, 1.2 pounds of seed with a 90% purity and 90% total germination would be needed for each pound specified in the desired seed mix.
A less expensive mix with lower purity and percent germination might require much more bulk seed to compensate for the lower PLS percentage.
At Ernst Seeds, our seeding rates are based on bulk seed unless otherwise indicated.