Read the analysis label before choosing a rate
The front of a grass-seed bag describes the product. The analysis label identifies what is in it. Read both before entering area, seed rate and package weight in the grass-seed calculator.
USDA’s Federal Seed Act program identifies purity, germination, noxious weed seed information, treatment information and kind or varietal identification among the labeling requirements for interstate seed shipments. Use the actual bag’s label rather than a generic description of the brand.
Keep the label fields separate
| Field | Meaning for the purchase | Do not assume |
|---|---|---|
| Kind and variety | Identify the grasses in the product | That every blend with the same marketing name has the same composition. |
| Purity | The stated proportion of seed in the analysis | That package weight and pure seed weight are identical. |
| Germination | The reported test result under its test conditions | That the same proportion will establish in the lawn. |
| Other seed, weed seed and inert matter | Other components in the labeled analysis | That these components are part of the desired grass seed. |
| Test information and treatment | Information needed to interpret and handle the product | That a label from a different lot describes this bag. |
| Application directions | The rate and use conditions for this product | That a new-lawn rate is also the overseeding rate. |
Use the rate on the correct basis
Identify whether the project is a new lawn or overseeding, then find the appropriate product rate. Confirm whether that rate applies to the product as sold or to a separately specified pure-seed basis. If the bag includes coating or other material, do not silently treat the entire package as pure grass seed.
The calculator’s mass output multiplies area in square feet ÷ 1,000 by the entered pounds-per-1,000-square-feet rate. Its bag output divides that product requirement by the entered package weight and rounds up. It does not automatically correct for purity, germination or coating.
When comparing bags, keep composition, rate basis, package weight and project area together. Two prices per pound do not establish equal suitability or equal project cost if the products or application directions differ.
Worked example: convert a labeled product rate to a purchase
- Inputs
- A 1,000 ft² area uses an illustrative product-as-sold rate of 7 lb/1,000 ft². The same product is sold in 10 lb bags.
- Calculation
Product required: 1,000 ÷ 1,000 × 7 = 7 lb. Bags: ceil(7 ÷ 10) = 1. Unused package amount: 10 − 7 = 3 lb.- Result
- Apply the stated 7 lb; purchase 1 bag
The 7 lb rate is an example, not a species recommendation. The calculator does not apply a hidden purity or germination correction, and the 3 lb surplus is not an additional application.
Record what you will apply and what you will buy
Keep the required seed mass separate from the package count. A whole bag may contain more product than the calculated application needs. Buying it does not mean that the extra material should be spread on the same area.
Save the label and record the planted area, selected rate, method and date. Use local guidance for species selection, soil preparation and establishment. The seed calculator provides quantity arithmetic after those choices have been made.
- Product, kind, variety and lot
- Space to write when printed
- Purity, germination and test information
- Space to write when printed
- New-lawn or overseeding use
- Space to write when printed
- Labeled rate and its product-weight basis
- Space to write when printed
- Measured area, required product mass and bag weight
- Space to write when printed
- Whole bags purchased and amount actually applied
- Space to write when printed
Conclusion
Read the actual label, choose a rate for the intended use and keep its weight basis consistent with the calculator input. Calculate the application mass first and round only the package count.