Pure Live Seed
To make better-informed decisions, it’s important to understand what Pure Live Seed (PLS) is and how it affects both the price and the product you purchase. Most introduced species are sold by bulk weight, whereas native plant seed may be sold by either bulk weight or PLS. See below to learn how PLS is calculated, how it impacts bulk weight, and why it’s important to order your native plant seeds by Pure Live Seed.
Purity & Germination
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About Pure Live Seed
“PLS” stands for Pure Live Seed, which refers to the portion of a seed lot that is guaranteed to be viable. The PLS weight reflects only the live, plantable seed—excluding empty seeds, dead seeds, leaves, stems, dirt, weed seeds, and other contaminants.
Each seed lot is tested by a government-certified lab, which determines two key values:
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Purity (%) – the percentage of actual seed in the lot
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Germination (%) – the percentage of that seed capable of germinating
To calculate PLS:
PLS (%) = Purity (%) × Germination (%)
At Roundstone, we sell all of our native seed by the PLS pound—because to us, PLS means quality you can count on.
Pure Live Seed—just one more reason to choose Roundstone.
PLS vs. Bulk
At Roundstone, all of our native seed is sold by Pure Live Seed (PLS) weight. This means our seed has been tested by a government-certified lab, and you’re only paying for the seed that is guaranteed to be viable. You’re not paying for empty seeds, dead seeds, stems, leaves, dirt, weed seeds, or other contaminants—unlike seed sold by bulk weight, which includes all of those non-viable materials.
When you pay only for viable seed, the difference in cost and value can be significant.
Let’s say you're buying seed for a species that has 100,000 seeds per pound:
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PLS Price: $36.00/lb at 63% PLS
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Bulk Price: $29.00/lb (same species, same seed count)
Now let’s do the math:
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PLS Cost = $36.00 for 100,000 viable seeds
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Bulk Cost = $46.03 for 100,000 viable seeds
What seems like a 24% savings with bulk pricing actually turns out to be 28% more expensive when you factor in seed viability—and the lower the PLS percentage, the worse it gets.
NOTE: The seeding rates for USDA Farm Bill Programs using native seed are in PLS pounds and the use of Bulk Weight to fulfill the seeding rates can be a cause for contract compliance failure—a costly mistake.
Cost Effectiveness
All of our native seed is sold by Pure Live Seed (PLS) weight—and that’s important for you.
PLS means that a government-certified testing lab has verified the seed’s viability, and we only charge you for the portion of seed that is guaranteed to grow. You're not paying for empty seeds, dead seeds, stems, leaves, dirt, weed seeds, or any other contaminants—unlike seed sold by bulk weight.
When you buy from Roundstone Native Seed, you're paying only for viable seed, and that can make a big difference in your cost—and your results.
Quality
Quality starts when we are preparing our production fields for establishment and doesn’t end until you receive your seed. Quality isn’t a buzzword at Roundstone Native Seed – we know that if your seed is no good, won’t germinate, is full of trash, contains lots of weed seeds, then no matter how carefully you prepare your site or how much time and money you invest in controlling competition, you simply won’t get a successful stand.
That’s why everything we do is focused on ensuring seed quality.
We have 17 precise cleaning and separation operations available to clean seed. Vacuum seed transfer is used to prevent damage. All seed is de-bearded to the extent possible without damaging the product, and seed acquired from other producers is routinely re-cleaned and re-tested.
Viability
This means our seed has been tested by a government-certified lab, and you're only paying for the portion that is guaranteed to be viable. You’re not paying for empty seeds, dead seeds, leaves, stems, dirt, weed seeds, or any other contaminants—unlike seed sold by bulk weight.
At Roundstone Native Seed, you pay only for viable seed, and that can make a significant difference in both cost and results.