Read the seed analysis tag before comparing bags: species and varieties, purity, germination, test date, crop seed, weed seed, inert matter and noxious weed notes describe what is in the package. Match the species to your region, soil, light and moisture before weighing the label percentages. Federal rules cover certain interstate seed shipments, while regional species recommendations and seed rules can differ.
The seed label helps you compare what is inside each bag, but its percentages answer different questions. Read the species and varieties first, then compare purity, germination, test date, crop seed, weed seed and inert matter. Use local extension guidance to choose species that suit your climate and site.
Start with your lawn conditions
Before looking at a label, note how much sun the lawn receives, its soil and moisture, and how you use the space. Grass species vary in their needs. University of Minnesota Extension recommends matching species to site conditions and points out that seed bags can include inert material, weed seeds, other crops and seed that will not germinate.
A blend combines varieties of the same grass species. A mixture includes more than one species. Local extension recommendations are more useful than a universal mix because climate, soil and lawn use differ by region.
Read the seed analysis tag
| Label field | What it tells you |
|---|---|
| Species and variety | Which grass seed components are present; compare them with local recommendations. |
| Purity | The percentage by weight of each listed seed component, not the share that will germinate. |
| Germination | The share of pure seed capable of germinating under laboratory conditions, not a field-establishment promise. |
| Test date | When the seed was tested; UMass Extension notes that germination declines as seed ages. |
| Crop seed, weed seed and inert matter | Other contents in the package; compare each line, not only the headline purity number. |
| Noxious weeds | Species and amounts named on the label; check state or local guidance for regulated weeds. |
For a closer comparison, UMass Extension describes pure live seed as purity multiplied by germination. It is a way to estimate how much of a named component is capable of germinating based on the label test, not a prediction that the same amount will establish in your yard.
Check the rules and regional fit
USDA’s Federal Seed Act information covers labeling for seed shipped between states and describes required quality information such as purity, germination, noxious weed seeds, and kind and variety identification. USDA works with state partners, and local requirements can add context to the label. The UMN guide is specific to Minnesota, so use your own state’s extension service for species and weed guidance in your area.
For the next steps after choosing seed, compare grass seed and sod for a new lawn, then see our lawn aeration and overseeding guide, how to mow your lawn, and lawn care category.
Sources
- USDA Agricultural Marketing Service: Federal Seed Act (accessed 2026-11-04).
- UMass Extension: Understanding a Turfgrass Seed Label (accessed 2026-11-04).
- University of Minnesota Extension: Buying turfgrass seed for Minnesota lawns (accessed 2026-11-04).
Common questions
Does 90 percent seed purity mean 90 percent will grow?
No. Purity is the share by weight of the named seed component, while germination is a separate laboratory-tested measure. The two can be combined to estimate pure live seed, but field establishment also depends on growing conditions.
What does weed seed percentage mean on a grass seed label?
It identifies the share of weed seed in the package by weight. Also read the noxious weed statement and local seed guidance because regulated species and requirements can differ by place.
Should I buy a grass seed blend or mixture?
First choose species that fit your region and site conditions. A blend combines varieties of one species, while a mixture contains more than one species; local extension guidance helps determine which fits your lawn.